diff --git a/README.md b/README.md
index a6451c0..764fb5c 100644
--- a/README.md
+++ b/README.md
@@ -231,9 +231,9 @@
 After downloading the datasets, open the `org.apache.flink.training.exercises.common.utils.ExerciseBase` class in your IDE, and edit these two lines to point to the two taxi ride data files you have downloaded:
 
 ```java
-public final static String pathToRideData =   
+public final static String PATH_TO_RIDE_DATA =
     "/Users/david/stuff/flink-training/trainingData/nycTaxiRides.gz";
-public final static String pathToFareData =
+public final static String PATH_TO_FARE_DATA =
     "/Users/david/stuff/flink-training/trainingData/nycTaxiFares.gz";
 ```
 
diff --git a/build.gradle b/build.gradle
index 7337d18..5e54c95 100644
--- a/build.gradle
+++ b/build.gradle
@@ -26,6 +26,7 @@
         apply plugin: 'application'
     }
     apply plugin: 'com.github.johnrengelman.shadow'
+    apply plugin: 'checkstyle'
 
     // artifact properties
     group = 'org.apache.flink'
@@ -85,7 +86,6 @@
         implementation "org.slf4j:slf4j-log4j12:${slf4jVersion}"
 
         flinkShadowJar "joda-time:joda-time:2.7"
-        flinkShadowJar "com.google.guava:guava:19.0"
 
         if (project != project(":common")) {
             implementation project(path: ':common')
diff --git a/common/src/main/java/org/apache/flink/training/examples/ridecount/RideCountExample.java b/common/src/main/java/org/apache/flink/training/examples/ridecount/RideCountExample.java
index 1ccc331..fe17f93 100644
--- a/common/src/main/java/org/apache/flink/training/examples/ridecount/RideCountExample.java
+++ b/common/src/main/java/org/apache/flink/training/examples/ridecount/RideCountExample.java
@@ -29,23 +29,31 @@
 import org.apache.flink.training.exercises.common.sources.TaxiRideSource;
 import org.apache.flink.training.exercises.common.utils.ExerciseBase;
 
-
 /**
  * Example that counts the rides for each driver.
  *
- * Parameters:
+ * <p>Parameters:
  *   -input path-to-input-file
  *
- * 	Note that this is implicitly keeping state for each driver.
- * 	This sort of simple, non-windowed aggregation on an unbounded set of keys will use an unbounded amount of state.
- * 	When this is an issue, look at the SQL/Table API, or ProcessFunction, or state TTL, all of which provide
- * 	mechanisms for expiring state for stale keys.
+ * <p>Note that this is implicitly keeping state for each driver.
+ * This sort of simple, non-windowed aggregation on an unbounded set of keys will use an unbounded amount of state.
+ * When this is an issue, look at the SQL/Table API, or ProcessFunction, or state TTL, all of which provide
+ * mechanisms for expiring state for stale keys.
  */
 public class RideCountExample {
+
+	/**
+	 * Main method.
+	 *
+	 * <p>Parameters:
+	 *   -input path-to-input-file
+	 *
+	 * @throws Exception which occurs during job execution.
+	 */
 	public static void main(String[] args) throws Exception {
 
 		ParameterTool params = ParameterTool.fromArgs(args);
-		final String input = params.get("input", ExerciseBase.pathToRideData);
+		final String input = params.get("input", ExerciseBase.PATH_TO_RIDE_DATA);
 
 		final int maxEventDelay = 60;       // events are out of order by max 60 seconds
 		final int servingSpeedFactor = 600; // events of 10 minutes are served every second
@@ -60,7 +68,7 @@
 		DataStream<Tuple2<Long, Long>> tuples = rides.map(new MapFunction<TaxiRide, Tuple2<Long, Long>>() {
 					@Override
 					public Tuple2<Long, Long> map(TaxiRide ride) throws Exception {
-						return new Tuple2<Long, Long>(ride.driverId, 1L) ;
+						return new Tuple2<Long, Long>(ride.driverId, 1L);
 					}
 		});
 
diff --git a/common/src/main/java/org/apache/flink/training/exercises/common/datatypes/TaxiFare.java b/common/src/main/java/org/apache/flink/training/exercises/common/datatypes/TaxiFare.java
index 429717c..393638e 100644
--- a/common/src/main/java/org/apache/flink/training/exercises/common/datatypes/TaxiFare.java
+++ b/common/src/main/java/org/apache/flink/training/exercises/common/datatypes/TaxiFare.java
@@ -28,22 +28,26 @@
 /**
  * A TaxiFare is a taxi fare event.
  *
- * A TaxiFare consists of
+ * <p>A TaxiFare consists of
  * - the rideId of the event
  * - the time of the event
- *
  */
 public class TaxiFare implements Serializable {
 
 	private static transient DateTimeFormatter timeFormatter =
 			DateTimeFormat.forPattern("yyyy-MM-dd HH:mm:ss").withLocale(Locale.US).withZoneUTC();
 
+	/**
+	 * Creates a TaxiFare with now as start time.
+	 */
 	public TaxiFare() {
 		this.startTime = new DateTime();
 	}
 
+	/**
+	 * Creates a TaxiFare with the given parameters.
+	 */
 	public TaxiFare(long rideId, long taxiId, long driverId, DateTime startTime, String paymentType, float tip, float tolls, float totalFare) {
-
 		this.rideId = rideId;
 		this.taxiId = taxiId;
 		this.driverId = driverId;
@@ -63,6 +67,7 @@
 	public float tolls;
 	public float totalFare;
 
+	@Override
 	public String toString() {
 		StringBuilder sb = new StringBuilder();
 		sb.append(rideId).append(",");
@@ -77,6 +82,9 @@
 		return sb.toString();
 	}
 
+	/**
+	 * Parse a TaxiFare from a CSV representation.
+	 */
 	public static TaxiFare fromString(String line) {
 
 		String[] tokens = line.split(",");
@@ -111,9 +119,12 @@
 
 	@Override
 	public int hashCode() {
-		return (int)this.rideId;
+		return (int) this.rideId;
 	}
 
+	/**
+	 * Gets the fare's start time.
+	 */
 	public long getEventTime() {
 		return startTime.getMillis();
 	}
diff --git a/common/src/main/java/org/apache/flink/training/exercises/common/datatypes/TaxiRide.java b/common/src/main/java/org/apache/flink/training/exercises/common/datatypes/TaxiRide.java
index 8dea262..7c78dec 100644
--- a/common/src/main/java/org/apache/flink/training/exercises/common/datatypes/TaxiRide.java
+++ b/common/src/main/java/org/apache/flink/training/exercises/common/datatypes/TaxiRide.java
@@ -18,7 +18,6 @@
 
 package org.apache.flink.training.exercises.common.datatypes;
 
-
 import org.apache.flink.training.exercises.common.utils.GeoUtils;
 
 import org.joda.time.DateTime;
@@ -32,7 +31,7 @@
  * A TaxiRide is a taxi ride event. There are two types of events, a taxi ride start event and a
  * taxi ride end event. The isStart flag specifies the type of the event.
  *
- * A TaxiRide consists of
+ * <p>A TaxiRide consists of
  * - the rideId of the event which is identical for start and end record
  * - the type of the event (start or end)
  * - the time of the event
@@ -43,22 +42,26 @@
  * - the passengerCnt of the ride
  * - the taxiId
  * - the driverId
- *
  */
 public class TaxiRide implements Comparable<TaxiRide>, Serializable {
 
 	private static transient DateTimeFormatter timeFormatter =
 			DateTimeFormat.forPattern("yyyy-MM-dd HH:mm:ss").withLocale(Locale.US).withZoneUTC();
 
+	/**
+	 * Creates a new TaxiRide with now as start and end time.
+	 */
 	public TaxiRide() {
 		this.startTime = new DateTime();
 		this.endTime = new DateTime();
 	}
 
+	/**
+	 * Creates a TaxiRide with the given parameters.
+	 */
 	public TaxiRide(long rideId, boolean isStart, DateTime startTime, DateTime endTime,
 					float startLon, float startLat, float endLon, float endLat,
 					short passengerCnt, long taxiId, long driverId) {
-
 		this.rideId = rideId;
 		this.isStart = isStart;
 		this.startTime = startTime;
@@ -84,6 +87,7 @@
 	public long taxiId;
 	public long driverId;
 
+	@Override
 	public String toString() {
 		StringBuilder sb = new StringBuilder();
 		sb.append(rideId).append(",");
@@ -101,6 +105,9 @@
 		return sb.toString();
 	}
 
+	/**
+	 * Parse a TaxiRide from a CSV representation.
+	 */
 	public static TaxiRide fromString(String line) {
 
 		String[] tokens = line.split(",");
@@ -143,8 +150,14 @@
 		return ride;
 	}
 
-	// sort by timestamp,
-	// putting START events before END events if they have the same timestamp
+	/**
+	 * Compares this TaxiRide with the given one.
+	 *
+	 * <ul>
+	 *     <li>sort by timestamp,</li>
+	 *     <li>putting START events before END events if they have the same timestamp</li>
+	 * </ul>
+	 */
 	public int compareTo(TaxiRide other) {
 		if (other == null) {
 			return 1;
@@ -176,9 +189,12 @@
 
 	@Override
 	public int hashCode() {
-		return (int)this.rideId;
+		return (int) this.rideId;
 	}
 
+	/**
+	 * Gets the ride's time stamp (start or end time depending on {@link #isStart}).
+	 */
 	public long getEventTime() {
 		if (isStart) {
 			return startTime.getMillis();
@@ -188,6 +204,9 @@
 		}
 	}
 
+	/**
+	 * Gets the distance from the ride location to the given one.
+	 */
 	public double getEuclideanDistance(double longitude, double latitude) {
 		if (this.isStart) {
 			return GeoUtils.getEuclideanDistance((float) longitude, (float) latitude, this.startLon, this.startLat);
diff --git a/common/src/main/java/org/apache/flink/training/exercises/common/sources/TaxiFareSource.java b/common/src/main/java/org/apache/flink/training/exercises/common/sources/TaxiFareSource.java
index 63b77e7..c0f3c88 100644
--- a/common/src/main/java/org/apache/flink/training/exercises/common/sources/TaxiFareSource.java
+++ b/common/src/main/java/org/apache/flink/training/exercises/common/sources/TaxiFareSource.java
@@ -39,19 +39,20 @@
  * read from a gzipped input file. Each record has a time stamp and the input file must be
  * ordered by this time stamp.
  *
- * In order to simulate a realistic stream source, the SourceFunction serves events proportional to
+ * <p>In order to simulate a realistic stream source, the SourceFunction serves events proportional to
  * their timestamps. In addition, the serving of events can be delayed by a bounded random delay
  * which causes the events to be served slightly out-of-order of their timestamps.
  *
- * The serving speed of the SourceFunction can be adjusted by a serving speed factor.
+ * <p>The serving speed of the SourceFunction can be adjusted by a serving speed factor.
  * A factor of 60.0 increases the logical serving time by a factor of 60, i.e., events of one
  * minute (60 seconds) are served in 1 second.
  *
- * This SourceFunction is an EventSourceFunction and does continuously emit watermarks.
+ * <p>This SourceFunction is an EventSourceFunction and does continuously emit watermarks.
  * Hence it is able to operate in event time mode which is configured as follows:
  *
- *   StreamExecutionEnvironment.setStreamTimeCharacteristic(TimeCharacteristic.EventTime)
- *
+ * <code>
+ *     StreamExecutionEnvironment.setStreamTimeCharacteristic(TimeCharacteristic.EventTime)
+ * </code>
  */
 public class TaxiFareSource implements SourceFunction<TaxiFare> {
 
@@ -97,7 +98,7 @@
 	 * @param servingSpeedFactor The serving speed factor by which the logical serving time is adjusted.
 	 */
 	public TaxiFareSource(String dataFilePath, int maxEventDelaySecs, int servingSpeedFactor) {
-		if(maxEventDelaySecs < 0) {
+		if (maxEventDelaySecs < 0) {
 			throw new IllegalArgumentException("Max event delay must be positive");
 		}
 		this.dataFilePath = dataFilePath;
@@ -168,12 +169,11 @@
 			// insert all events into schedule that might be emitted next
 			long curNextDelayedEventTime = !emitSchedule.isEmpty() ? emitSchedule.peek().f0 : -1;
 			long rideEventTime = fare != null ? getEventTime(fare) : -1;
-			while(
-					fare != null && ( // while there is a ride AND
+			while (
+					fare != null && (// while there is a ride AND
 						emitSchedule.isEmpty() || // and no ride in schedule OR
 						rideEventTime < curNextDelayedEventTime + maxDelayMsecs) // not enough rides in schedule
-					)
-			{
+					) {
 				// insert event into emit schedule
 				long delayedEventTime = rideEventTime + getNormalDelayMsecs(rand);
 				emitSchedule.add(new Tuple2<Long, Object>(delayedEventTime, fare));
@@ -197,15 +197,15 @@
 			long servingTime = toServingTime(servingStartTime, dataStartTime, delayedEventTime);
 			long waitTime = servingTime - now;
 
-			Thread.sleep( (waitTime > 0) ? waitTime : 0);
+			Thread.sleep((waitTime > 0) ? waitTime : 0);
 
-			if(head.f1 instanceof TaxiFare) {
-				TaxiFare emitFare = (TaxiFare)head.f1;
+			if (head.f1 instanceof TaxiFare) {
+				TaxiFare emitFare = (TaxiFare) head.f1;
 				// emit ride
 				sourceContext.collectWithTimestamp(emitFare, getEventTime(emitFare));
 			}
-			else if(head.f1 instanceof Watermark) {
-				Watermark emitWatermark = (Watermark)head.f1;
+			else if (head.f1 instanceof Watermark) {
+				Watermark emitWatermark = (Watermark) head.f1;
 				// emit watermark
 				sourceContext.emitWatermark(emitWatermark);
 				// schedule next watermark
@@ -216,20 +216,20 @@
 		}
 	}
 
-	public long toServingTime(long servingStartTime, long dataStartTime, long eventTime) {
+	protected long toServingTime(long servingStartTime, long dataStartTime, long eventTime) {
 		long dataDiff = eventTime - dataStartTime;
 		return servingStartTime + (dataDiff / this.servingSpeed);
 	}
 
-	public long getEventTime(TaxiFare fare) {
+	protected long getEventTime(TaxiFare fare) {
 		return fare.getEventTime();
 	}
 
-	public long getNormalDelayMsecs(Random rand) {
+	protected long getNormalDelayMsecs(Random rand) {
 		long delay = -1;
 		long x = maxDelayMsecs / 2;
-		while(delay < 0 || delay > maxDelayMsecs) {
-			delay = (long)(rand.nextGaussian() * x) + x;
+		while (delay < 0 || delay > maxDelayMsecs) {
+			delay = (long) (rand.nextGaussian() * x) + x;
 		}
 		return delay;
 	}
@@ -243,7 +243,7 @@
 			if (this.gzipStream != null) {
 				this.gzipStream.close();
 			}
-		} catch(IOException ioe) {
+		} catch (IOException ioe) {
 			throw new RuntimeException("Could not cancel SourceFunction", ioe);
 		} finally {
 			this.reader = null;
diff --git a/common/src/main/java/org/apache/flink/training/exercises/common/sources/TaxiRideSource.java b/common/src/main/java/org/apache/flink/training/exercises/common/sources/TaxiRideSource.java
index f57c41c..6bfb970 100644
--- a/common/src/main/java/org/apache/flink/training/exercises/common/sources/TaxiRideSource.java
+++ b/common/src/main/java/org/apache/flink/training/exercises/common/sources/TaxiRideSource.java
@@ -39,19 +39,20 @@
  * read from a gzipped input file. Each record has a time stamp and the input file must be
  * ordered by this time stamp.
  *
- * In order to simulate a realistic stream source, the SourceFunction serves events proportional to
+ * <p>In order to simulate a realistic stream source, the SourceFunction serves events proportional to
  * their timestamps. In addition, the serving of events can be delayed by a bounded random delay
  * which causes the events to be served slightly out-of-order of their timestamps.
  *
- * The serving speed of the SourceFunction can be adjusted by a serving speed factor.
+ * <p>The serving speed of the SourceFunction can be adjusted by a serving speed factor.
  * A factor of 60.0 increases the logical serving time by a factor of 60, i.e., events of one
  * minute (60 seconds) are served in 1 second.
  *
- * This SourceFunction is an EventSourceFunction and does continuously emit watermarks.
+ * <p>This SourceFunction is an EventSourceFunction and does continuously emit watermarks.
  * Hence it is able to operate in event time mode which is configured as follows:
  *
- *   StreamExecutionEnvironment.setStreamTimeCharacteristic(TimeCharacteristic.EventTime)
- *
+ * <code>
+ *     StreamExecutionEnvironment.setStreamTimeCharacteristic(TimeCharacteristic.EventTime)
+ * </code>
  */
 public class TaxiRideSource implements SourceFunction<TaxiRide> {
 
@@ -97,7 +98,7 @@
 	 * @param servingSpeedFactor The serving speed factor by which the logical serving time is adjusted.
 	 */
 	public TaxiRideSource(String dataFilePath, int maxEventDelaySecs, int servingSpeedFactor) {
-		if(maxEventDelaySecs < 0) {
+		if (maxEventDelaySecs < 0) {
 			throw new IllegalArgumentException("Max event delay must be positive");
 		}
 		this.dataFilePath = dataFilePath;
@@ -168,12 +169,11 @@
 			// insert all events into schedule that might be emitted next
 			long curNextDelayedEventTime = !emitSchedule.isEmpty() ? emitSchedule.peek().f0 : -1;
 			long rideEventTime = ride != null ? getEventTime(ride) : -1;
-			while(
-					ride != null && ( // while there is a ride AND
+			while (
+					ride != null && (// while there is a ride AND
 						emitSchedule.isEmpty() || // and no ride in schedule OR
 						rideEventTime < curNextDelayedEventTime + maxDelayMsecs) // not enough rides in schedule
-					)
-			{
+					) {
 				// insert event into emit schedule
 				long delayedEventTime = rideEventTime + getNormalDelayMsecs(rand);
 				emitSchedule.add(new Tuple2<Long, Object>(delayedEventTime, ride));
@@ -197,15 +197,15 @@
 			long servingTime = toServingTime(servingStartTime, dataStartTime, delayedEventTime);
 			long waitTime = servingTime - now;
 
-			Thread.sleep( (waitTime > 0) ? waitTime : 0);
+			Thread.sleep((waitTime > 0) ? waitTime : 0);
 
-			if(head.f1 instanceof TaxiRide) {
-				TaxiRide emitRide = (TaxiRide)head.f1;
+			if (head.f1 instanceof TaxiRide) {
+				TaxiRide emitRide = (TaxiRide) head.f1;
 				// emit ride
 				sourceContext.collectWithTimestamp(emitRide, getEventTime(emitRide));
 			}
-			else if(head.f1 instanceof Watermark) {
-				Watermark emitWatermark = (Watermark)head.f1;
+			else if (head.f1 instanceof Watermark) {
+				Watermark emitWatermark = (Watermark) head.f1;
 				// emit watermark
 				sourceContext.emitWatermark(emitWatermark);
 				// schedule next watermark
@@ -216,20 +216,20 @@
 		}
 	}
 
-	public long toServingTime(long servingStartTime, long dataStartTime, long eventTime) {
+	protected long toServingTime(long servingStartTime, long dataStartTime, long eventTime) {
 		long dataDiff = eventTime - dataStartTime;
 		return servingStartTime + (dataDiff / this.servingSpeed);
 	}
 
-	public long getEventTime(TaxiRide ride) {
+	protected long getEventTime(TaxiRide ride) {
 		return ride.getEventTime();
 	}
 
-	public long getNormalDelayMsecs(Random rand) {
+	protected long getNormalDelayMsecs(Random rand) {
 		long delay = -1;
 		long x = maxDelayMsecs / 2;
-		while(delay < 0 || delay > maxDelayMsecs) {
-			delay = (long)(rand.nextGaussian() * x) + x;
+		while (delay < 0 || delay > maxDelayMsecs) {
+			delay = (long) (rand.nextGaussian() * x) + x;
 		}
 		return delay;
 	}
@@ -243,7 +243,7 @@
 			if (this.gzipStream != null) {
 				this.gzipStream.close();
 			}
-		} catch(IOException ioe) {
+		} catch (IOException ioe) {
 			throw new RuntimeException("Could not cancel SourceFunction", ioe);
 		} finally {
 			this.reader = null;
diff --git a/common/src/main/java/org/apache/flink/training/exercises/common/utils/ExerciseBase.java b/common/src/main/java/org/apache/flink/training/exercises/common/utils/ExerciseBase.java
index b910710..3440a15 100644
--- a/common/src/main/java/org/apache/flink/training/exercises/common/utils/ExerciseBase.java
+++ b/common/src/main/java/org/apache/flink/training/exercises/common/utils/ExerciseBase.java
@@ -23,6 +23,9 @@
 import org.apache.flink.training.exercises.common.datatypes.TaxiFare;
 import org.apache.flink.training.exercises.common.datatypes.TaxiRide;
 
+/**
+ * Base for all exercises with a few helper methods.
+ */
 public class ExerciseBase {
 	public static SourceFunction<TaxiRide> rides = null;
 	public static SourceFunction<TaxiFare> fares = null;
@@ -30,9 +33,12 @@
 	public static SinkFunction out = null;
 	public static int parallelism = 4;
 
-	public final static String pathToRideData = "/Users/david/stuff/flink-training/trainingData/nycTaxiRides.gz";
-	public final static String pathToFareData = "/Users/david/stuff/flink-training/trainingData/nycTaxiFares.gz";
+	public static final String PATH_TO_RIDE_DATA = "/Users/david/stuff/flink-training/trainingData/nycTaxiRides.gz";
+	public static final String PATH_TO_FARE_DATA = "/Users/david/stuff/flink-training/trainingData/nycTaxiFares.gz";
 
+	/**
+	 * Retrieves a test source during unit tests and the given one during normal execution.
+	 */
 	public static SourceFunction<TaxiRide> rideSourceOrTest(SourceFunction<TaxiRide> source) {
 		if (rides == null) {
 			return source;
@@ -40,6 +46,9 @@
 		return rides;
 	}
 
+	/**
+	 * Retrieves a test source during unit tests and the given one during normal execution.
+	 */
 	public static SourceFunction<TaxiFare> fareSourceOrTest(SourceFunction<TaxiFare> source) {
 		if (fares == null) {
 			return source;
@@ -47,6 +56,9 @@
 		return fares;
 	}
 
+	/**
+	 * Retrieves a test source during unit tests and the given one during normal execution.
+	 */
 	public static SourceFunction<String> stringSourceOrTest(SourceFunction<String> source) {
 		if (strings == null) {
 			return source;
@@ -54,6 +66,9 @@
 		return strings;
 	}
 
+	/**
+	 * Prints the given data stream during normal execution and collects outputs during tests.
+	 */
 	public static void printOrTest(org.apache.flink.streaming.api.datastream.DataStream<?> ds) {
 		if (out == null) {
 			ds.print();
@@ -62,6 +77,9 @@
 		}
 	}
 
+	/**
+	 * Prints the given data stream during normal execution and collects outputs during tests.
+	 */
 	public static void printOrTest(org.apache.flink.streaming.api.scala.DataStream<?> ds) {
 		if (out == null) {
 			ds.print();
@@ -69,4 +87,4 @@
 			ds.addSink(out);
 		}
 	}
-}
\ No newline at end of file
+}
diff --git a/common/src/main/java/org/apache/flink/training/exercises/common/utils/GeoUtils.java b/common/src/main/java/org/apache/flink/training/exercises/common/utils/GeoUtils.java
index 9f5d084..4594248 100644
--- a/common/src/main/java/org/apache/flink/training/exercises/common/utils/GeoUtils.java
+++ b/common/src/main/java/org/apache/flink/training/exercises/common/utils/GeoUtils.java
@@ -28,25 +28,25 @@
 public class GeoUtils {
 
 	// geo boundaries of the area of NYC
-	public static double LON_EAST = -73.7;
-	public static double LON_WEST = -74.05;
-	public static double LAT_NORTH = 41.0;
-	public static double LAT_SOUTH = 40.5;
+	public static final double LON_EAST = -73.7;
+	public static final double LON_WEST = -74.05;
+	public static final double LAT_NORTH = 41.0;
+	public static final double LAT_SOUTH = 40.5;
 
 	// area width and height
-	public static double LON_WIDTH = 74.05 - 73.7;
-	public static double LAT_HEIGHT = 41.0 - 40.5;
+	public static final double LON_WIDTH = 74.05 - 73.7;
+	public static final double LAT_HEIGHT = 41.0 - 40.5;
 
 	// delta step to create artificial grid overlay of NYC
-	public static double DELTA_LON = 0.0014;
-	public static double DELTA_LAT = 0.00125;
+	public static final double DELTA_LON = 0.0014;
+	public static final double DELTA_LAT = 0.00125;
 
 	// ( |LON_WEST| - |LON_EAST| ) / DELTA_LAT
-	public static int NUMBER_OF_GRID_X = 250;
+	public static final int NUMBER_OF_GRID_X = 250;
 	// ( LAT_NORTH - LAT_SOUTH ) / DELTA_LON
-	public static int NUMBER_OF_GRID_Y = 400;
+	public static final int NUMBER_OF_GRID_Y = 400;
 
-	public static float DEG_LEN = 110.25f;
+	public static final float DEG_LEN = 110.25f;
 
 	/**
 	 * Checks if a location specified by longitude and latitude values is
@@ -103,7 +103,7 @@
 		int y2 = (int) Math.floor((LAT_NORTH - lat2) / DELTA_LAT);
 
 		int startX, startY, endX, endY;
-		if(x1 <= x2) {
+		if (x1 <= x2) {
 			startX = x1;
 			startY = y1;
 			endX = x2;
@@ -116,7 +116,7 @@
 			endY = y1;
 		}
 
-		double slope = (endY - startY) / ((endX - startX)+0.00000001);
+		double slope = (endY - startY) / ((endX - startX) + 0.00000001);
 
 		int curX = startX;
 		int curY = startY;
@@ -124,16 +124,16 @@
 		ArrayList<Integer> cellIds = new ArrayList<>(64);
 		cellIds.add(curX + (curY * NUMBER_OF_GRID_X));
 
-		while(curX < endX || curY != endY) {
+		while (curX < endX || curY != endY) {
 
-			if(slope > 0) {
+			if (slope > 0) {
 				double y = (curX - startX + 0.5) * slope + startY - 0.5;
 
-				if(y > curY - 0.05 && y < curY + 0.05) {
+				if (y > curY - 0.05 && y < curY + 0.05) {
 					curX++;
 					curY++;
 				}
-				else if(y < curY) {
+				else if (y < curY) {
 					curX++;
 				}
 				else {
@@ -143,11 +143,11 @@
 			else {
 				double y = (curX - startX + 0.5) * slope + startY + 0.5;
 
-				if(y > curY - 0.05 && y < curY + 0.05) {
+				if (y > curY - 0.05 && y < curY + 0.05) {
 					curX++;
 					curY--;
 				}
-				if(y > curY) {
+				if (y > curY) {
 					curX++;
 				}
 				else {
@@ -173,7 +173,7 @@
 
 		int xIndex = gridCellId % NUMBER_OF_GRID_X;
 
-		return (float)(Math.abs(LON_WEST) - (xIndex * DELTA_LON) - (DELTA_LON / 2)) * -1.0f;
+		return (float) (Math.abs(LON_WEST) - (xIndex * DELTA_LON) - (DELTA_LON / 2)) * -1.0f;
 	}
 
 	/**
@@ -188,7 +188,7 @@
 		int xIndex = gridCellId % NUMBER_OF_GRID_X;
 		int yIndex = (gridCellId - xIndex) / NUMBER_OF_GRID_X;
 
-		return (float)(LAT_NORTH - (yIndex * DELTA_LAT) - (DELTA_LAT / 2));
+		return (float) (LAT_NORTH - (yIndex * DELTA_LAT) - (DELTA_LAT / 2));
 
 	}
 
@@ -199,7 +199,7 @@
 	 * @return A random longitude value within the NYC area.
 	 */
 	public static float getRandomNYCLon(Random rand) {
-		return (float)(LON_EAST - (LON_WIDTH * rand.nextFloat()));
+		return (float) (LON_EAST - (LON_WIDTH * rand.nextFloat()));
 	}
 
 	/**
@@ -209,7 +209,7 @@
 	 * @return A random latitude value within the NYC area.
 	 */
 	public static float getRandomNYCLat(Random rand) {
-		return (float)(LAT_SOUTH + (LAT_HEIGHT * rand.nextFloat()));
+		return (float) (LAT_SOUTH + (LAT_HEIGHT * rand.nextFloat()));
 	}
 
 	/**
@@ -224,14 +224,14 @@
 	public static double getEuclideanDistance(float lon1, float lat1, float lon2, float lat2) {
 		double x = lat1 - lat2;
 		double y = (lon1 - lon2) * Math.cos(lat2);
-		return (DEG_LEN * Math.sqrt(x*x + y*y));
+		return (DEG_LEN * Math.sqrt(x * x + y * y));
 	}
 
 	/**
 	 * Returns the angle in degrees between the vector from the start to the destination
 	 * and the x-axis on which the start is located.
 	 *
-	 * The angle describes in which direction the destination is located from the start, i.e.,
+	 * <p>The angle describes in which direction the destination is located from the start, i.e.,
 	 * 0° -> East, 90° -> South, 180° -> West, 270° -> North
 	 *
 	 * @param startLon longitude of start location
diff --git a/common/src/main/java/org/apache/flink/training/exercises/common/utils/MissingSolutionException.java b/common/src/main/java/org/apache/flink/training/exercises/common/utils/MissingSolutionException.java
index 7d9a977..4f6c95f 100644
--- a/common/src/main/java/org/apache/flink/training/exercises/common/utils/MissingSolutionException.java
+++ b/common/src/main/java/org/apache/flink/training/exercises/common/utils/MissingSolutionException.java
@@ -18,18 +18,12 @@
 
 package org.apache.flink.training.exercises.common.utils;
 
+/**
+ * Exception denoting a missing solution (results in tests verifying the solution instead).
+ */
 public class MissingSolutionException extends Exception {
-	public MissingSolutionException() {};
-
-	public MissingSolutionException(String message) {
-		super(message);
-	};
-
-	public MissingSolutionException(Throwable cause) {
-		super(cause);
-	}
-
-	public MissingSolutionException(String message, Throwable cause) {
-		super(message, cause);
-	}
-};
+	/**
+	 * Create new exception.
+	 */
+	public MissingSolutionException() {}
+}
diff --git a/common/src/test/java/org/apache/flink/training/exercises/testing/TaxiRideTestBase.java b/common/src/test/java/org/apache/flink/training/exercises/testing/TaxiRideTestBase.java
index c5b6f95..6c59de1 100644
--- a/common/src/test/java/org/apache/flink/training/exercises/testing/TaxiRideTestBase.java
+++ b/common/src/test/java/org/apache/flink/training/exercises/testing/TaxiRideTestBase.java
@@ -66,11 +66,11 @@
 	public static class TestSink<OUT> implements SinkFunction<OUT> {
 
 		// must be static
-		public static final List values = new ArrayList<>();
+		public static final List VALUES = new ArrayList<>();
 
 		@Override
 		public void invoke(OUT value, Context context) throws Exception {
-			values.add(value);
+			VALUES.add(value);
 		}
 	}
 
@@ -111,7 +111,7 @@
 	}
 
 	private List<OUT> execute(TestSink<OUT> sink, Testable exercise, Testable solution) throws Exception {
-		sink.values.clear();
+		sink.VALUES.clear();
 
 		ExerciseBase.out = sink;
 		ExerciseBase.parallelism = 1;
@@ -120,25 +120,25 @@
 			exercise.main();
 		} catch (Exception e) {
 			if (ultimateCauseIsMissingSolution(e)) {
-				sink.values.clear();
+				sink.VALUES.clear();
 				solution.main();
 			} else {
 				throw e;
 			}
 		}
 
-		return sink.values;
+		return sink.VALUES;
 	}
 
 	private List<OUT> execute(TestSink<OUT> sink, Testable solution) throws Exception {
-		sink.values.clear();
+		sink.VALUES.clear();
 
 		ExerciseBase.out = sink;
 		ExerciseBase.parallelism = 1;
 
 		solution.main();
 
-		return sink.values;
+		return sink.VALUES;
 	}
 
 	private boolean ultimateCauseIsMissingSolution(Throwable e) {
diff --git a/config/checkstyle/checkstyle.xml b/config/checkstyle/checkstyle.xml
new file mode 100644
index 0000000..34b0e76
--- /dev/null
+++ b/config/checkstyle/checkstyle.xml
@@ -0,0 +1,570 @@
+<?xml version="1.0"?>
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+<!DOCTYPE module PUBLIC
+          "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
+          "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">
+
+<!--
+This is a checkstyle configuration file. For descriptions of
+what the following rules do, please see the checkstyle configuration
+page at http://checkstyle.sourceforge.net/config.html.
+
+This file is based on the checkstyle file of Apache Beam.
+-->
+
+<module name="Checker">
+
+  <!--<module name="FileTabCharacter">-->
+    <!--&lt;!&ndash; Checks that there are no tab characters in the file. &ndash;&gt;-->
+  <!--</module>-->
+
+  <module name="NewlineAtEndOfFile">
+    <!-- windows can use \r\n vs \n, so enforce the most used one ie UNIx style -->
+    <property name="lineSeparator" value="lf" />
+  </module>
+
+  <module name="RegexpSingleline">
+    <!-- Checks that TODOs don't have stuff in parenthesis, e.g., username. -->
+    <property name="format" value="((//.*)|(\*.*))TODO\(" />
+    <property name="message" value="TODO comments must not include usernames." />
+    <property name="severity" value="error" />
+  </module>
+
+  <module name="RegexpSingleline">
+    <property name="format" value="\s+$"/>
+    <property name="message" value="Trailing whitespace"/>
+    <property name="severity" value="error"/>
+  </module>
+
+  <module name="RegexpSingleline">
+    <property name="format" value="Throwables.propagate\("/>
+    <property name="message" value="Throwables.propagate is deprecated"/>
+    <property name="severity" value="error"/>
+  </module>
+
+  <!-- Prevent *Tests.java as tools may not pick them up -->
+  <!--<module name="RegexpOnFilename">-->
+    <!--<property name="fileNamePattern" value=".*Tests\.java$" />-->
+  <!--</module>-->
+
+  <module name="SuppressionFilter">
+    <property name="file" value="${config_loc}/suppressions.xml" default="suppressions.xml" />
+  </module>
+
+  <!-- Check that every module has a package-info.java -->
+  <!--<module name="JavadocPackage"/>-->
+
+  <!--
+
+  FLINK CUSTOM CHECKS
+
+  -->
+
+  <module name="FileLength">
+    <property name="max" value="3000"/>
+  </module>
+
+  <!-- All Java AST specific tests live under TreeWalker module. -->
+  <module name="TreeWalker">
+
+    <!-- Allow use of comment to suppress javadocstyle -->
+    <module name="SuppressionCommentFilter">
+      <property name="offCommentFormat" value="CHECKSTYLE.OFF\: ([\w\|]+)"/>
+      <property name="onCommentFormat" value="CHECKSTYLE.ON\: ([\w\|]+)"/>
+      <property name="checkFormat" value="$1"/>
+    </module>
+
+    <!--
+
+    FLINK CUSTOM CHECKS
+
+    -->
+
+    <module name="RegexpSinglelineJava">
+      <property name="format" value="^\t* +\t*\S" />
+      <property name="message"
+                value="Line has leading space characters; indentation should be performed with tabs only." />
+      <property name="ignoreComments" value="true" />
+    </module>
+
+    <!-- Prohibit T.getT() methods for standard boxed types -->
+    <module name="Regexp">
+      <property name="format" value="Boolean\.getBoolean"/>
+      <property name="illegalPattern" value="true"/>
+      <property name="message" value="Use System.getProperties() to get system properties."/>
+    </module>
+
+    <module name="Regexp">
+      <property name="format" value="Integer\.getInteger"/>
+      <property name="illegalPattern" value="true"/>
+      <property name="message" value="Use System.getProperties() to get system properties."/>
+    </module>
+
+    <module name="Regexp">
+      <property name="format" value="Long\.getLong"/>
+      <property name="illegalPattern" value="true"/>
+      <property name="message" value="Use System.getProperties() to get system properties."/>
+    </module>
+
+    <!--
+
+    IllegalImport cannot blacklist classes so we have to fall back to Regexp.
+
+    -->
+
+    <!-- forbid use of commons lang validate -->
+    <module name="Regexp">
+      <property name="format" value="org\.apache\.commons\.lang3\.Validate"/>
+      <property name="illegalPattern" value="true"/>
+      <property name="message" value="Use Guava Checks instead of Commons Validate. Please refer to the coding guidelines."/>
+    </module>
+    <!-- forbid the use of google.common.base.Preconditions -->
+    <module name="Regexp">
+      <property name="format" value="import com\.google\.common\.base\.Preconditions"/>
+      <property name="illegalPattern" value="true"/>
+      <property name="message" value="Use Flink's Preconditions instead of Guava's Preconditions"/>
+    </module>
+    <!-- forbid the use of com.google.common.annotations.VisibleForTesting -->
+    <module name="Regexp">
+      <property name="format" value="import com\.google\.common\.annotations\.VisibleForTesting"/>
+      <property name="illegalPattern" value="true"/>
+      <property name="message" value="Use Flink's VisibleForTesting instead of Guava's VisibleForTesting"/>
+    </module>
+    <module name="Regexp">
+      <property name="format" value="import static com\.google\.common\.base\.Preconditions"/>
+      <property name="illegalPattern" value="true"/>
+      <property name="message" value="Use Flink's Preconditions instead of Guava's Preconditions"/>
+    </module>
+    <!-- forbid the use of org.apache.commons.lang.SerializationUtils -->
+    <module name="Regexp">
+      <property name="format" value="org\.apache\.commons\.lang\.SerializationUtils"/>
+      <property name="illegalPattern" value="true"/>
+      <property name="message" value="Use Flink's InstantiationUtil instead of common's SerializationUtils"/>
+    </module>
+    <module name="Regexp">
+      <property name="format" value="org\.apache\.commons\.lang3\.SerializationUtils"/>
+      <property name="illegalPattern" value="true"/>
+      <property name="message" value="Use Flink's InstantiationUtil instead of common's SerializationUtils"/>
+    </module>
+    <module name="Regexp">
+      <property name="format" value="org\.apache\.commons\.lang\."/>
+      <property name="illegalPattern" value="true"/>
+      <property name="message" value="Use commons-lang3 instead of commons-lang."/>
+    </module>
+    <module name="Regexp">
+      <property name="format" value="org\.codehaus\.jettison"/>
+      <property name="illegalPattern" value="true"/>
+      <property name="message" value="Use com.fasterxml.jackson instead of jettison."/>
+    </module>
+
+    <!-- Enforce Java-style array declarations -->
+    <module name="ArrayTypeStyle" />
+
+    <module name="TodoComment">
+      <!-- Checks that disallowed strings are not used in comments.  -->
+      <property name="format" value="(FIXME)|(XXX)|(@author)" />
+    </module>
+
+    <!--
+
+    IMPORT CHECKS
+
+    -->
+
+    <module name="RedundantImport">
+      <!-- Checks for redundant import statements. -->
+      <property name="severity" value="error"/>
+      <message key="import.redundancy"
+               value="Redundant import {0}."/>
+    </module>
+
+    <module name="ImportOrder">
+      <!-- Checks for out of order import statements. -->
+      <property name="severity" value="error"/>
+      <property name="groups" value="org.apache.flink,org.apache.flink.shaded,*,javax,java,scala"/>
+      <property name="separated" value="true"/>
+      <property name="sortStaticImportsAlphabetically" value="true"/>
+      <property name="option" value="bottom"/>
+      <property name="tokens" value="STATIC_IMPORT, IMPORT"/>
+      <message key="import.ordering"
+               value="Import {0} appears after other imports that it should precede"/>
+    </module>
+
+    <module name="AvoidStarImport">
+      <property name="severity" value="error"/>
+    </module>
+
+    <module name="IllegalImport">
+      <property name="illegalPkgs" value="autovalue.shaded, avro.shaded, com.google.api.client.repackaged, com.google.appengine.repackaged, org.codehaus.jackson, io.netty, org.objectweb.asm, com.google.common"/>
+    </module>
+
+    <module name="RedundantModifier">
+      <!-- Checks for redundant modifiers on various symbol definitions.
+        See: http://checkstyle.sourceforge.net/config_modifier.html#RedundantModifier
+        
+        We exclude METHOD_DEF to allow final methods in final classes to make them more future-proof.
+      -->
+      <property name="tokens" value="VARIABLE_DEF, ANNOTATION_FIELD_DEF, INTERFACE_DEF, CLASS_DEF, ENUM_DEF"/>
+    </module>
+
+    <!--
+        IllegalImport cannot blacklist classes, and c.g.api.client.util is used for some shaded
+        code and some useful code. So we need to fall back to Regexp.
+    -->
+    <!--<module name="RegexpSinglelineJava">-->
+      <!--<property name="format" value="com\.google\.api\.client\.util\.(ByteStreams|Charsets|Collections2|Joiner|Lists|Maps|Objects|Preconditions|Sets|Strings|Throwables)"/>-->
+    <!--</module>-->
+
+    <!--
+         Require static importing from Preconditions.
+    -->
+    <module name="RegexpSinglelineJava">
+      <property name="format" value="^import com.google.common.base.Preconditions;$"/>
+      <property name="message" value="Static import functions from Guava Preconditions"/>
+    </module>
+
+    <module name="UnusedImports">
+      <property name="severity" value="error"/>
+      <property name="processJavadoc" value="true"/>
+      <message key="import.unused"
+               value="Unused import: {0}."/>
+    </module>
+
+    <!--
+
+    JAVADOC CHECKS
+
+    -->
+
+    <!-- Checks for Javadoc comments.                     -->
+    <!-- See http://checkstyle.sf.net/config_javadoc.html -->
+    <module name="JavadocMethod">
+      <property name="scope" value="protected"/>
+      <property name="severity" value="error"/>
+      <property name="allowMissingParamTags" value="true"/>
+      <property name="allowMissingReturnTag" value="true"/>
+      <property name="validateThrows" value="false"/>
+    </module>
+
+    <module name="MissingJavadocMethod">
+    </module>
+
+    <!-- Check that paragraph tags are used correctly in Javadoc. -->
+    <module name="JavadocParagraph"/>
+
+    <module name="JavadocType">
+      <property name="scope" value="protected"/>
+      <property name="severity" value="error"/>
+      <property name="allowMissingParamTags" value="true"/>
+    </module>
+
+    <module name="JavadocStyle">
+      <property name="severity" value="error"/>
+      <property name="checkHtml" value="true"/>
+    </module>
+
+    <!--
+
+    NAMING CHECKS
+
+    -->
+
+    <!-- Item 38 - Adhere to generally accepted naming conventions -->
+
+    <module name="PackageName">
+      <!-- Validates identifiers for package names against the
+        supplied expression. -->
+      <!-- Here the default checkstyle rule restricts package name parts to
+        seven characters, this is not in line with common practice at Google.
+      -->
+      <property name="format" value="^[a-z]+(\.[a-z][a-z0-9]{1,})*$"/>
+      <property name="severity" value="error"/>
+    </module>
+
+    <module name="TypeNameCheck">
+      <!-- Validates static, final fields against the
+      expression "^[A-Z][a-zA-Z0-9]*$". -->
+      <metadata name="altname" value="TypeName"/>
+      <property name="severity" value="error"/>
+    </module>
+
+    <module name="ConstantNameCheck">
+      <!-- Validates non-private, static, final fields against the supplied
+      public/package final fields "^[A-Z][A-Z0-9]*(_[A-Z0-9]+)*$". -->
+      <metadata name="altname" value="ConstantName"/>
+      <property name="applyToPublic" value="true"/>
+      <property name="applyToProtected" value="true"/>
+      <property name="applyToPackage" value="true"/>
+      <property name="applyToPrivate" value="false"/>
+      <property name="format" value="^([A-Z][A-Z0-9]*(_[A-Z0-9]+)*|FLAG_.*)$"/>
+      <message key="name.invalidPattern"
+               value="Variable ''{0}'' should be in ALL_CAPS (if it is a constant) or be private (otherwise)."/>
+      <property name="severity" value="error"/>
+    </module>
+
+    <module name="StaticVariableNameCheck">
+      <!-- Validates static, non-final fields against the supplied
+      expression "^[a-z][a-zA-Z0-9]*_?$". -->
+      <metadata name="altname" value="StaticVariableName"/>
+      <property name="applyToPublic" value="true"/>
+      <property name="applyToProtected" value="true"/>
+      <property name="applyToPackage" value="true"/>
+      <property name="applyToPrivate" value="true"/>
+      <property name="format" value="^[a-z][a-zA-Z0-9]*_?$"/>
+      <property name="severity" value="error"/>
+    </module>
+
+    <module name="MemberNameCheck">
+      <!-- Validates non-static members against the supplied expression. -->
+      <metadata name="altname" value="MemberName"/>
+      <property name="applyToPublic" value="true"/>
+      <property name="applyToProtected" value="true"/>
+      <property name="applyToPackage" value="true"/>
+      <property name="applyToPrivate" value="true"/>
+      <property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
+      <property name="severity" value="error"/>
+    </module>
+
+    <module name="MethodNameCheck">
+      <!-- Validates identifiers for method names. -->
+      <metadata name="altname" value="MethodName"/>
+      <property name="format" value="^[a-z][a-zA-Z0-9]*(_[a-zA-Z0-9]+)*$"/>
+      <property name="severity" value="error"/>
+    </module>
+
+    <module name="ParameterName">
+      <!-- Validates identifiers for method parameters against the
+        expression "^[a-z][a-zA-Z0-9]*$". -->
+      <property name="severity" value="error"/>
+    </module>
+
+    <module name="LocalFinalVariableName">
+      <!-- Validates identifiers for local final variables against the
+        expression "^[a-z][a-zA-Z0-9]*$". -->
+      <property name="severity" value="error"/>
+    </module>
+
+    <module name="LocalVariableName">
+      <!-- Validates identifiers for local variables against the
+        expression "^[a-z][a-zA-Z0-9]*$". -->
+      <property name="severity" value="error"/>
+    </module>
+
+    <!-- Type parameters must be either one of the four blessed letters
+    T, K, V, W, X or else be capital-case terminated with a T,
+    such as MyGenericParameterT -->
+    <!--<module name="ClassTypeParameterName">-->
+      <!--<property name="format" value="^(((T|K|V|W|X)[0-9]*)|([A-Z][a-z][a-zA-Z]*T))$"/>-->
+      <!--<property name="severity" value="error"/>-->
+    <!--</module>-->
+
+    <!--<module name="MethodTypeParameterName">-->
+      <!--<property name="format" value="^(((T|K|V|W|X)[0-9]*)|([A-Z][a-z][a-zA-Z]*T))$"/>-->
+      <!--<property name="severity" value="error"/>-->
+    <!--</module>-->
+
+    <!--<module name="InterfaceTypeParameterName">-->
+      <!--<property name="format" value="^(((T|K|V|W|X)[0-9]*)|([A-Z][a-z][a-zA-Z]*T))$"/>-->
+      <!--<property name="severity" value="error"/>-->
+    <!--</module>-->
+
+    <!--
+
+    LENGTH and CODING CHECKS
+
+    -->
+
+    <!--<module name="LineLength">-->
+      <!--&lt;!&ndash; Checks if a line is too long. &ndash;&gt;-->
+      <!--<property name="max" value="100"/>-->
+      <!--<property name="severity" value="error"/>-->
+
+      <!--&lt;!&ndash;-->
+        <!--The default ignore pattern exempts the following elements:-->
+          <!-- - import statements-->
+          <!-- - long URLs inside comments-->
+      <!--&ndash;&gt;-->
+
+      <!--<property name="ignorePattern"-->
+          <!--value="^(package .*;\s*)|(import .*;\s*)|( *\* .*https?://.*)$"/>-->
+    <!--</module>-->
+
+    <module name="LeftCurly">
+      <!-- Checks for placement of the left curly brace ('{'). -->
+      <property name="severity" value="error"/>
+    </module>
+
+    <!--<module name="RightCurly">-->
+      <!--&lt;!&ndash; Checks right curlies on CATCH, ELSE, and TRY blocks are on-->
+      <!--the same line. e.g., the following example is fine:-->
+      <!--<pre>-->
+        <!--if {-->
+          <!--...-->
+        <!--} else-->
+      <!--</pre>-->
+      <!--&ndash;&gt;-->
+      <!--&lt;!&ndash; This next example is not fine:-->
+      <!--<pre>-->
+        <!--if {-->
+          <!--...-->
+        <!--}-->
+        <!--else-->
+      <!--</pre>-->
+      <!--&ndash;&gt;-->
+      <!--<property name="option" value="same"/>-->
+      <!--<property name="severity" value="error"/>-->
+    <!--</module>-->
+
+    <!-- Checks for braces around if and else blocks -->
+    <module name="NeedBraces">
+      <property name="severity" value="error"/>
+      <property name="tokens" value="LITERAL_IF, LITERAL_ELSE, LITERAL_FOR, LITERAL_WHILE, LITERAL_DO"/>
+    </module>
+
+    <module name="UpperEll">
+      <!-- Checks that long constants are defined with an upper ell.-->
+      <property name="severity" value="error"/>
+    </module>
+
+    <module name="FallThrough">
+      <!-- Warn about falling through to the next case statement.  Similar to
+      javac -Xlint:fallthrough, but the check is suppressed if a single-line comment
+      on the last non-blank line preceding the fallen-into case contains 'fall through' (or
+      some other variants that we don't publicized to promote consistency).
+      -->
+      <property name="reliefPattern"
+       value="fall through|Fall through|fallthru|Fallthru|falls through|Falls through|fallthrough|Fallthrough|No break|NO break|no break|continue on"/>
+      <property name="severity" value="error"/>
+    </module>
+
+    <!-- Checks for over-complicated boolean expressions. -->
+    <module name="SimplifyBooleanExpression"/>
+
+    <!-- Detects empty statements (standalone ";" semicolon). -->
+    <module name="EmptyStatement"/>
+
+	<!-- Detect multiple consecutive semicolons (e.g. ";;"). -->
+	<module name="RegexpSinglelineJava">
+	  <property name="format" value=";{2,}"/>
+	  <property name="message" value="Use one semicolon"/>
+	  <property name="ignoreComments" value="true"/>
+	</module>
+
+    <!--
+
+    MODIFIERS CHECKS
+
+    -->
+
+    <module name="ModifierOrder">
+      <!-- Warn if modifier order is inconsistent with JLS3 8.1.1, 8.3.1, and
+           8.4.3.  The prescribed order is:
+           public, protected, private, abstract, static, final, transient, volatile,
+           synchronized, native, strictfp
+        -->
+      <property name="severity" value="error"/>
+    </module>
+
+
+    <!--
+
+    WHITESPACE CHECKS
+
+    -->
+
+    <module name="EmptyLineSeparator">
+      <!-- Checks for empty line separator between tokens. The only
+           excluded token is VARIABLE_DEF, allowing class fields to
+           be declared on consecutive lines.
+      -->
+      <property name="allowMultipleEmptyLines" value="false"/>
+      <property name="allowMultipleEmptyLinesInsideClassMembers" value="false"/>
+      <property name="tokens" value="PACKAGE_DEF, IMPORT, STATIC_IMPORT, CLASS_DEF,
+        INTERFACE_DEF, ENUM_DEF, STATIC_INIT, INSTANCE_INIT, METHOD_DEF,
+        CTOR_DEF"/>
+    </module>
+
+    <module name="WhitespaceAround">
+      <!-- Checks that various tokens are surrounded by whitespace.
+           This includes most binary operators and keywords followed
+           by regular or curly braces.
+      -->
+      <property name="tokens" value="ASSIGN, BAND, BAND_ASSIGN, BOR,
+        BOR_ASSIGN, BSR, BSR_ASSIGN, BXOR, BXOR_ASSIGN, COLON, DIV, DIV_ASSIGN,
+        EQUAL, GE, GT, LAMBDA, LAND, LE, LITERAL_CATCH, LITERAL_DO, LITERAL_ELSE,
+        LITERAL_FINALLY, LITERAL_FOR, LITERAL_IF, LITERAL_RETURN,
+        LITERAL_SYNCHRONIZED, LITERAL_TRY, LITERAL_WHILE, LOR, LT, MINUS,
+        MINUS_ASSIGN, MOD, MOD_ASSIGN, NOT_EQUAL, PLUS, PLUS_ASSIGN, QUESTION,
+        SL, SL_ASSIGN, SR_ASSIGN, STAR, STAR_ASSIGN, TYPE_EXTENSION_AND"/>
+      <property name="severity" value="error"/>
+    </module>
+
+    <module name="WhitespaceAfter">
+      <!-- Checks that commas, semicolons and typecasts are followed by
+           whitespace.
+      -->
+      <property name="tokens" value="COMMA, SEMI, TYPECAST"/>
+    </module>
+
+    <module name="NoWhitespaceAfter">
+      <!-- Checks that there is no whitespace after various unary operators.
+           Linebreaks are allowed.
+      -->
+      <property name="tokens" value="BNOT, DEC, DOT, INC, LNOT, UNARY_MINUS,
+        UNARY_PLUS"/>
+      <property name="allowLineBreaks" value="true"/>
+      <property name="severity" value="error"/>
+    </module>
+
+    <module name="NoWhitespaceBefore">
+      <!-- Checks that there is no whitespace before various unary operators.
+           Linebreaks are allowed.
+      -->
+      <property name="tokens" value="SEMI, DOT, POST_DEC, POST_INC"/>
+      <property name="allowLineBreaks" value="true"/>
+      <property name="severity" value="error"/>
+    </module>
+
+    <!--<module name="OperatorWrap">-->
+      <!--&lt;!&ndash; Checks that operators like + and ? appear at newlines rather than-->
+           <!--at the end of the previous line.-->
+      <!--&ndash;&gt;-->
+      <!--<property name="option" value="NL"/>-->
+      <!--<property name="tokens" value="BAND, BOR, BSR, BXOR, DIV, EQUAL,-->
+        <!--GE, GT, LAND, LE, LITERAL_INSTANCEOF, LOR, LT, MINUS, MOD,-->
+        <!--NOT_EQUAL, PLUS, QUESTION, SL, SR, STAR "/>-->
+    <!--</module>-->
+
+    <module name="OperatorWrap">
+      <!-- Checks that assignment operators are at the end of the line. -->
+      <property name="option" value="eol"/>
+      <property name="tokens" value="ASSIGN"/>
+    </module>
+
+    <module name="ParenPad">
+      <!-- Checks that there is no whitespace before close parens or after
+           open parens.
+      -->
+      <property name="severity" value="error"/>
+    </module>
+
+  </module>
+</module>
+
diff --git a/config/checkstyle/suppressions.xml b/config/checkstyle/suppressions.xml
new file mode 100644
index 0000000..0b05a64
--- /dev/null
+++ b/config/checkstyle/suppressions.xml
@@ -0,0 +1,29 @@
+<?xml version="1.0"?>
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+<!DOCTYPE suppressions PUBLIC
+		"-//Puppy Crawl//DTD Suppressions 1.1//EN"
+		"http://www.puppycrawl.com/dtds/suppressions_1_1.dtd">
+
+<suppressions>
+	<suppress
+			files="(.*)test[/\\](.*)"
+			checks="MissingJavadocMethod"/>
+</suppressions>
diff --git a/hourly-tips/src/main/java/org/apache/flink/training/exercises/hourlytips/HourlyTipsExercise.java b/hourly-tips/src/main/java/org/apache/flink/training/exercises/hourlytips/HourlyTipsExercise.java
index ca2d5ec..b926de1 100644
--- a/hourly-tips/src/main/java/org/apache/flink/training/exercises/hourlytips/HourlyTipsExercise.java
+++ b/hourly-tips/src/main/java/org/apache/flink/training/exercises/hourlytips/HourlyTipsExercise.java
@@ -30,20 +30,27 @@
 /**
  * The "Hourly Tips" exercise of the Flink training in the docs.
  *
- * The task of the exercise is to first calculate the total tips collected by each driver, hour by hour, and
+ * <p>The task of the exercise is to first calculate the total tips collected by each driver, hour by hour, and
  * then from that stream, find the highest tip total in each hour.
  *
- * Parameters:
+ * <p>Parameters:
  * -input path-to-input-file
- *
  */
 public class HourlyTipsExercise extends ExerciseBase {
 
+	/**
+	 * Main method.
+	 *
+	 * <p>Parameters:
+	 * -input path-to-input-file
+	 *
+	 * @throws Exception which occurs during job execution.
+	 */
 	public static void main(String[] args) throws Exception {
 
 		// read parameters
 		ParameterTool params = ParameterTool.fromArgs(args);
-		final String input = params.get("input", ExerciseBase.pathToFareData);
+		final String input = params.get("input", ExerciseBase.PATH_TO_FARE_DATA);
 
 		final int maxEventDelay = 60;       // events are out of order by max 60 seconds
 		final int servingSpeedFactor = 600; // events of 10 minutes are served in 1 second
diff --git a/hourly-tips/src/main/scala/org/apache/flink/training/exercises/hourlytips/scala/HourlyTipsExercise.scala b/hourly-tips/src/main/scala/org/apache/flink/training/exercises/hourlytips/scala/HourlyTipsExercise.scala
index eda02e4..ec38975 100644
--- a/hourly-tips/src/main/scala/org/apache/flink/training/exercises/hourlytips/scala/HourlyTipsExercise.scala
+++ b/hourly-tips/src/main/scala/org/apache/flink/training/exercises/hourlytips/scala/HourlyTipsExercise.scala
@@ -33,7 +33,6 @@
   *
   * Parameters:
   * -input path-to-input-file
-  *
   */
 object HourlyTipsExercise {
 
@@ -41,7 +40,7 @@
 
     // read parameters
     val params = ParameterTool.fromArgs(args)
-    val input = params.get("input", ExerciseBase.pathToFareData)
+    val input = params.get("input", ExerciseBase.PATH_TO_FARE_DATA)
 
     val maxDelay = 60 // events are delayed by at most 60 seconds
     val speed = 600   // events of 10 minutes are served in 1 second
diff --git a/hourly-tips/src/solution/java/org/apache/flink/training/solutions/hourlytips/HourlyTipsSolution.java b/hourly-tips/src/solution/java/org/apache/flink/training/solutions/hourlytips/HourlyTipsSolution.java
index dedfd24..4e2bb32 100644
--- a/hourly-tips/src/solution/java/org/apache/flink/training/solutions/hourlytips/HourlyTipsSolution.java
+++ b/hourly-tips/src/solution/java/org/apache/flink/training/solutions/hourlytips/HourlyTipsSolution.java
@@ -34,20 +34,27 @@
 /**
  * Java reference implementation for the "Hourly Tips" exercise of the Flink training in the docs.
  *
- * The task of the exercise is to first calculate the total tips collected by each driver, hour by hour, and
+ * <p>The task of the exercise is to first calculate the total tips collected by each driver, hour by hour, and
  * then from that stream, find the highest tip total in each hour.
  *
- * Parameters:
+ * <p>Parameters:
  * -input path-to-input-file
- *
  */
 public class HourlyTipsSolution extends ExerciseBase {
 
+	/**
+	 * Main method.
+	 *
+	 * <p>Parameters:
+	 * -input path-to-input-file
+	 *
+	 * @throws Exception which occurs during job execution.
+	 */
 	public static void main(String[] args) throws Exception {
 
 		// read parameters
 		ParameterTool params = ParameterTool.fromArgs(args);
-		final String input = params.get("input", ExerciseBase.pathToFareData);
+		final String input = params.get("input", ExerciseBase.PATH_TO_FARE_DATA);
 
 		final int maxEventDelay = 60;       // events are out of order by max 60 seconds
 		final int servingSpeedFactor = 600; // events of 10 minutes are served in 1 second
diff --git a/hourly-tips/src/solution/scala/org/apache/flink/training/solutions/hourlytips/scala/HourlyTipsSolution.scala b/hourly-tips/src/solution/scala/org/apache/flink/training/solutions/hourlytips/scala/HourlyTipsSolution.scala
index 7a32046..3ad6243 100644
--- a/hourly-tips/src/solution/scala/org/apache/flink/training/solutions/hourlytips/scala/HourlyTipsSolution.scala
+++ b/hourly-tips/src/solution/scala/org/apache/flink/training/solutions/hourlytips/scala/HourlyTipsSolution.scala
@@ -38,7 +38,6 @@
   *
   * Parameters:
   * -input path-to-input-file
-  *
   */
 object HourlyTipsSolution {
 
@@ -46,7 +45,7 @@
 
     // read parameters
     val params = ParameterTool.fromArgs(args)
-    val input = params.get("input", ExerciseBase.pathToFareData)
+    val input = params.get("input", ExerciseBase.PATH_TO_FARE_DATA)
 
     val maxDelay = 60 // events are delayed by at most 60 seconds
     val speed = 600   // events of 10 minutes are served in 1 second
diff --git a/hourly-tips/src/test/java/org/apache/flink/training/exercises/hourlytips/HourlyTipsTest.java b/hourly-tips/src/test/java/org/apache/flink/training/exercises/hourlytips/HourlyTipsTest.java
index 2a4c70a..565a8d3 100644
--- a/hourly-tips/src/test/java/org/apache/flink/training/exercises/hourlytips/HourlyTipsTest.java
+++ b/hourly-tips/src/test/java/org/apache/flink/training/exercises/hourlytips/HourlyTipsTest.java
@@ -23,12 +23,12 @@
 import org.apache.flink.training.exercises.testing.TaxiRideTestBase;
 import org.apache.flink.training.solutions.hourlytips.HourlyTipsSolution;
 
-import com.google.common.collect.Lists;
 import org.joda.time.DateTime;
 import org.joda.time.DateTimeZone;
 import org.junit.Test;
 
-import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 
 import static org.junit.Assert.assertEquals;
@@ -47,7 +47,7 @@
 
 		Tuple3<Long, Long, Float> max = new Tuple3<Long, Long, Float>(t(60), 1L, 1.0F);
 
-		ArrayList<Tuple3<Long, Long, Float>> expected = Lists.newArrayList(max);
+		List<Tuple3<Long, Long, Float>> expected = Collections.singletonList(max);
 
 		assertEquals(expected, results(source));
 	}
@@ -67,7 +67,7 @@
 		Tuple3<Long, Long, Float> hour1 = new Tuple3<Long, Long, Float>(t(60), 1L, 6.0F);
 		Tuple3<Long, Long, Float> hour2 = new Tuple3<Long, Long, Float>(t(120), 1L, 10.0F);
 
-		ArrayList<Tuple3<Long, Long, Float>> expected = Lists.newArrayList(hour1, hour2);
+		List<Tuple3<Long, Long, Float>> expected = Arrays.asList(hour1, hour2);
 
 		assertEquals(expected, results(source));
 	}
@@ -89,7 +89,7 @@
 		Tuple3<Long, Long, Float> hour1 = new Tuple3<Long, Long, Float>(t(60), 1L, 6.0F);
 		Tuple3<Long, Long, Float> hour2 = new Tuple3<Long, Long, Float>(t(120), 2L, 20.0F);
 
-		ArrayList<Tuple3<Long, Long, Float>> expected = Lists.newArrayList(hour1, hour2);
+		List<Tuple3<Long, Long, Float>> expected = Arrays.asList(hour1, hour2);
 
 		assertEquals(expected, results(source));
 	}
@@ -107,4 +107,4 @@
 		return runApp(source, new TestSink<>(), javaExercise, javaSolution);
 	}
 
-}
\ No newline at end of file
+}
diff --git a/long-ride-alerts/src/main/java/org/apache/flink/training/exercises/longrides/LongRidesExercise.java b/long-ride-alerts/src/main/java/org/apache/flink/training/exercises/longrides/LongRidesExercise.java
index 3a291e8..327ba38 100644
--- a/long-ride-alerts/src/main/java/org/apache/flink/training/exercises/longrides/LongRidesExercise.java
+++ b/long-ride-alerts/src/main/java/org/apache/flink/training/exercises/longrides/LongRidesExercise.java
@@ -34,18 +34,26 @@
 /**
  * The "Long Ride Alerts" exercise of the Flink training in the docs.
  *
- * The goal for this exercise is to emit START events for taxi rides that have not been matched
+ * <p>The goal for this exercise is to emit START events for taxi rides that have not been matched
  * by an END event during the first 2 hours of the ride.
  *
- * Parameters:
+ * <p>Parameters:
  * -input path-to-input-file
- *
  */
 public class LongRidesExercise extends ExerciseBase {
+
+	/**
+	 * Main method.
+	 *
+	 * <p>Parameters:
+	 * -input path-to-input-file
+	 *
+	 * @throws Exception which occurs during job execution.
+	 */
 	public static void main(String[] args) throws Exception {
 
 		ParameterTool params = ParameterTool.fromArgs(args);
-		final String input = params.get("input", ExerciseBase.pathToRideData);
+		final String input = params.get("input", ExerciseBase.PATH_TO_RIDE_DATA);
 
 		final int maxEventDelay = 60;       // events are out of order by max 60 seconds
 		final int servingSpeedFactor = 600; // events of 10 minutes are served in 1 second
@@ -83,4 +91,4 @@
 		public void onTimer(long timestamp, OnTimerContext context, Collector<TaxiRide> out) throws Exception {
 		}
 	}
-}
\ No newline at end of file
+}
diff --git a/long-ride-alerts/src/main/scala/org/apache/flink/training/exercises/longrides/scala/LongRidesExercise.scala b/long-ride-alerts/src/main/scala/org/apache/flink/training/exercises/longrides/scala/LongRidesExercise.scala
index 966d7e4..49deb45 100644
--- a/long-ride-alerts/src/main/scala/org/apache/flink/training/exercises/longrides/scala/LongRidesExercise.scala
+++ b/long-ride-alerts/src/main/scala/org/apache/flink/training/exercises/longrides/scala/LongRidesExercise.scala
@@ -37,14 +37,14 @@
   *
   * Parameters:
   * -input path-to-input-file
-  *
   */
 object LongRidesExercise {
+
   def main(args: Array[String]) {
 
     // parse parameters
     val params = ParameterTool.fromArgs(args)
-    val input = params.get("input", ExerciseBase.pathToRideData)
+    val input = params.get("input", ExerciseBase.PATH_TO_RIDE_DATA)
 
     val maxDelay = 60     // events are out of order by max 60 seconds
     val speed = 1800      // events of 30 minutes are served every second
diff --git a/long-ride-alerts/src/solution/java/org/apache/flink/training/solutions/longrides/LongRidesSolution.java b/long-ride-alerts/src/solution/java/org/apache/flink/training/solutions/longrides/LongRidesSolution.java
index fe47cda..fb75ef2 100644
--- a/long-ride-alerts/src/solution/java/org/apache/flink/training/solutions/longrides/LongRidesSolution.java
+++ b/long-ride-alerts/src/solution/java/org/apache/flink/training/solutions/longrides/LongRidesSolution.java
@@ -35,19 +35,26 @@
 /**
  * Solution to the "Long Ride Alerts" exercise of the Flink training in the docs.
  *
- * The goal for this exercise is to emit START events for taxi rides that have not been matched
+ * <p>The goal for this exercise is to emit START events for taxi rides that have not been matched
  * by an END event during the first 2 hours of the ride.
  *
- * Parameters:
+ * <p>Parameters:
  * -input path-to-input-file
- *
  */
-
 public class LongRidesSolution extends ExerciseBase {
+
+	/**
+	 * Main method.
+	 *
+	 * <p>Parameters:
+	 * -input path-to-input-file
+	 *
+	 * @throws Exception which occurs during job execution.
+	 */
 	public static void main(String[] args) throws Exception {
 
 		ParameterTool params = ParameterTool.fromArgs(args);
-		final String input = params.get("input", ExerciseBase.pathToRideData);
+		final String input = params.get("input", ExerciseBase.PATH_TO_RIDE_DATA);
 
 		final int maxEventDelay = 60;       // events are out of order by max 60 seconds
 		final int servingSpeedFactor = 600; // events of 10 minutes are served in 1 second
diff --git a/long-ride-alerts/src/solution/scala/org/apache/flink/training/solutions/longrides/scala/LongRidesSolution.scala b/long-ride-alerts/src/solution/scala/org/apache/flink/training/solutions/longrides/scala/LongRidesSolution.scala
index 4e182ae..29e854c 100644
--- a/long-ride-alerts/src/solution/scala/org/apache/flink/training/solutions/longrides/scala/LongRidesSolution.scala
+++ b/long-ride-alerts/src/solution/scala/org/apache/flink/training/solutions/longrides/scala/LongRidesSolution.scala
@@ -37,7 +37,6 @@
   *
   * Parameters:
   * -input path-to-input-file
-  *
   */
 object LongRidesSolution {
 
@@ -45,7 +44,7 @@
 
     // parse parameters
     val params = ParameterTool.fromArgs(args)
-    val input = params.get("input", pathToRideData)
+    val input = params.get("input", PATH_TO_RIDE_DATA)
 
     val maxDelay = 60     // events are out of order by max 60 seconds
     val speed = 1800      // events of 30 minutes are served every second
diff --git a/long-ride-alerts/src/test/java/org/apache/flink/training/exercises/longrides/LongRidesTest.java b/long-ride-alerts/src/test/java/org/apache/flink/training/exercises/longrides/LongRidesTest.java
index 4000bc4..9bd68ae 100644
--- a/long-ride-alerts/src/test/java/org/apache/flink/training/exercises/longrides/LongRidesTest.java
+++ b/long-ride-alerts/src/test/java/org/apache/flink/training/exercises/longrides/LongRidesTest.java
@@ -22,10 +22,10 @@
 import org.apache.flink.training.exercises.testing.TaxiRideTestBase;
 import org.apache.flink.training.solutions.longrides.LongRidesSolution;
 
-import com.google.common.collect.Lists;
 import org.joda.time.DateTime;
 import org.junit.Test;
 
+import java.util.Collections;
 import java.util.List;
 
 import static org.junit.Assert.assertEquals;
@@ -75,7 +75,7 @@
 		Long markThreeHoursLater = beginning.plusHours(3).getMillis();
 
 		TestRideSource source = new TestRideSource(rideStarted, markThreeHoursLater);
-		assertEquals(Lists.newArrayList(rideStarted), results(source));
+		assertEquals(Collections.singletonList(rideStarted), results(source));
 	}
 
 	@Test
@@ -85,11 +85,11 @@
 		TaxiRide rideEnded3HoursLater = endRide(rideStarted, beginning.plusHours(3));
 
 		TestRideSource source = new TestRideSource(rideStarted, mark2HoursLater, rideEnded3HoursLater);
-		assertEquals(Lists.newArrayList(rideStarted), results(source));
+		assertEquals(Collections.singletonList(rideStarted), results(source));
 	}
 
 	private TaxiRide testRide(long rideId, Boolean isStart, DateTime startTime, DateTime endTime) {
-		return new TaxiRide(rideId, isStart, startTime, endTime, -73.9947F, 40.750626F, -73.9947F, 40.750626F, (short)1, 0, 0);
+		return new TaxiRide(rideId, isStart, startTime, endTime, -73.9947F, 40.750626F, -73.9947F, 40.750626F, (short) 1, 0, 0);
 	}
 
 	private TaxiRide startRide(long rideId, DateTime startTime) {
@@ -105,4 +105,4 @@
 		return runApp(source, new TestSink<>(), javaExercise, javaSolution);
 	}
 
-}
\ No newline at end of file
+}
diff --git a/ride-cleansing/src/main/java/org/apache/flink/training/exercises/ridecleansing/RideCleansingExercise.java b/ride-cleansing/src/main/java/org/apache/flink/training/exercises/ridecleansing/RideCleansingExercise.java
index d9e1247..7e73733 100644
--- a/ride-cleansing/src/main/java/org/apache/flink/training/exercises/ridecleansing/RideCleansingExercise.java
+++ b/ride-cleansing/src/main/java/org/apache/flink/training/exercises/ridecleansing/RideCleansingExercise.java
@@ -30,18 +30,28 @@
 /**
  * The "Ride Cleansing" exercise from the Flink training in the docs.
  *
- * The task of the exercise is to filter a data stream of taxi ride records to keep only rides that
+ * <p>The task of the exercise is to filter a data stream of taxi ride records to keep only rides that
  * start and end within New York City. The resulting stream should be printed.
  *
- * Parameters:
+ * <p>Parameters:
  *   -input path-to-input-file
- *
  */
 public class RideCleansingExercise extends ExerciseBase {
+
+	/**
+	 * Main method.
+	 *
+	 * <p>Parameters:
+	 *   -input path-to-input-file
+	 *
+	 * @throws Exception which occurs during job execution.
+	 *
+	 * @throws Exception which occurs during job execution.
+	 */
 	public static void main(String[] args) throws Exception {
 
 		ParameterTool params = ParameterTool.fromArgs(args);
-		final String input = params.get("input", ExerciseBase.pathToRideData);
+		final String input = params.get("input", ExerciseBase.PATH_TO_RIDE_DATA);
 
 		final int maxEventDelay = 60;       // events are out of order by max 60 seconds
 		final int servingSpeedFactor = 600; // events of 10 minutes are served in 1 second
diff --git a/ride-cleansing/src/main/scala/org/apache/flink/training/exercises/ridecleansing/scala/RideCleansingExercise.scala b/ride-cleansing/src/main/scala/org/apache/flink/training/exercises/ridecleansing/scala/RideCleansingExercise.scala
index cc5d7c9..a0e6c6b 100644
--- a/ride-cleansing/src/main/scala/org/apache/flink/training/exercises/ridecleansing/scala/RideCleansingExercise.scala
+++ b/ride-cleansing/src/main/scala/org/apache/flink/training/exercises/ridecleansing/scala/RideCleansingExercise.scala
@@ -35,10 +35,11 @@
  * -input path-to-input-file
  */
 object RideCleansingExercise extends ExerciseBase {
+
   def main(args: Array[String]) {
     // parse parameters
     val params = ParameterTool.fromArgs(args)
-    val input = params.get("input", ExerciseBase.pathToRideData)
+    val input = params.get("input", ExerciseBase.PATH_TO_RIDE_DATA)
 
     val maxDelay = 60 // events are out of order by max 60 seconds
     val speed = 600   // events of 10 minutes are served in 1 second
diff --git a/ride-cleansing/src/solution/java/org/apache/flink/training/solutions/ridecleansing/RideCleansingSolution.java b/ride-cleansing/src/solution/java/org/apache/flink/training/solutions/ridecleansing/RideCleansingSolution.java
index 1c849bd..cf3dca5 100644
--- a/ride-cleansing/src/solution/java/org/apache/flink/training/solutions/ridecleansing/RideCleansingSolution.java
+++ b/ride-cleansing/src/solution/java/org/apache/flink/training/solutions/ridecleansing/RideCleansingSolution.java
@@ -22,17 +22,34 @@
 import org.apache.flink.api.java.utils.ParameterTool;
 import org.apache.flink.streaming.api.datastream.DataStream;
 import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
-
 import org.apache.flink.training.exercises.common.datatypes.TaxiRide;
 import org.apache.flink.training.exercises.common.sources.TaxiRideSource;
 import org.apache.flink.training.exercises.common.utils.ExerciseBase;
 import org.apache.flink.training.exercises.common.utils.GeoUtils;
 
+/**
+ * Solution to the "Ride Cleansing" exercise of the Flink training in the docs.
+ *
+ * <p>The task of the exercise is to filter a data stream of taxi ride records to keep only rides that
+ * start and end within New York City. The resulting stream should be printed.
+ *
+ * <p>Parameters:
+ *   -input path-to-input-file
+ */
 public class RideCleansingSolution extends ExerciseBase {
+
+	/**
+	 * Main method.
+	 *
+	 * <p>Parameters:
+	 *   -input path-to-input-file
+	 *
+	 * @throws Exception which occurs during job execution.
+	 */
 	public static void main(String[] args) throws Exception {
 
 		ParameterTool params = ParameterTool.fromArgs(args);
-		final String input = params.get("input", pathToRideData);
+		final String input = params.get("input", PATH_TO_RIDE_DATA);
 
 		final int maxEventDelay = 60;       // events are out of order by max 60 seconds
 		final int servingSpeedFactor = 600; // events of 10 minutes are served in 1 second
diff --git a/ride-cleansing/src/solution/scala/org/apache/flink/training/solutions/ridecleansing/scala/RideCleansingSolution.scala b/ride-cleansing/src/solution/scala/org/apache/flink/training/solutions/ridecleansing/scala/RideCleansingSolution.scala
index 4874bbe..d831259 100644
--- a/ride-cleansing/src/solution/scala/org/apache/flink/training/solutions/ridecleansing/scala/RideCleansingSolution.scala
+++ b/ride-cleansing/src/solution/scala/org/apache/flink/training/solutions/ridecleansing/scala/RideCleansingSolution.scala
@@ -33,14 +33,13 @@
  *
  * Parameters:
  * -input path-to-input-file
- *
  */
 object RideCleansingSolution {
 
   def main(args: Array[String]) {
     // parse parameters
     val params = ParameterTool.fromArgs(args)
-    val input = params.get("input", pathToRideData)
+    val input = params.get("input", ExerciseBase.PATH_TO_RIDE_DATA)
 
     val maxDelay = 60 // events are out of order by max 60 seconds
     val speed = 600   // events of 10 minutes are served in 1 second
diff --git a/ride-cleansing/src/test/java/org/apache/flink/training/exercises/ridecleansing/RideCleansingTest.java b/ride-cleansing/src/test/java/org/apache/flink/training/exercises/ridecleansing/RideCleansingTest.java
index bce9ea0..b0e151f 100644
--- a/ride-cleansing/src/test/java/org/apache/flink/training/exercises/ridecleansing/RideCleansingTest.java
+++ b/ride-cleansing/src/test/java/org/apache/flink/training/exercises/ridecleansing/RideCleansingTest.java
@@ -18,7 +18,6 @@
 
 package org.apache.flink.training.exercises.ridecleansing;
 
-import com.google.common.collect.Lists;
 import org.apache.flink.training.exercises.common.datatypes.TaxiRide;
 import org.apache.flink.training.exercises.testing.TaxiRideTestBase;
 import org.apache.flink.training.solutions.ridecleansing.RideCleansingSolution;
@@ -26,6 +25,7 @@
 import org.joda.time.DateTime;
 import org.junit.Test;
 
+import java.util.Collections;
 import java.util.List;
 
 import static org.junit.Assert.assertEquals;
@@ -40,7 +40,7 @@
 
 		TestRideSource source = new TestRideSource(atPennStation);
 
-		assertEquals(Lists.newArrayList(atPennStation), results(source));
+		assertEquals(Collections.singletonList(atPennStation), results(source));
 	}
 
 	@Test
@@ -51,12 +51,12 @@
 
 		TestRideSource source = new TestRideSource(toThePole, fromThePole, atNorthPole);
 
-		assertEquals(Lists.newArrayList(), results(source));
+		assertEquals(Collections.emptyList(), results(source));
 	}
 
 	private TaxiRide testRide(float startLon, float startLat, float endLon, float endLat) {
 		return new TaxiRide(1L, true, new DateTime(0), new DateTime(0),
-				startLon, startLat, endLon, endLat, (short)1, 0, 0);
+				startLon, startLat, endLon, endLat, (short) 1, 0, 0);
 	}
 
 	protected List<?> results(TestRideSource source) throws Exception {
@@ -64,4 +64,4 @@
 		return runApp(source, new TestSink<>(), javaExercise, javaSolution);
 	}
 
-}
\ No newline at end of file
+}
diff --git a/rides-and-fares/src/main/java/org/apache/flink/training/exercises/ridesandfares/RidesAndFaresExercise.java b/rides-and-fares/src/main/java/org/apache/flink/training/exercises/ridesandfares/RidesAndFaresExercise.java
index 37eac20..4bae96c 100644
--- a/rides-and-fares/src/main/java/org/apache/flink/training/exercises/ridesandfares/RidesAndFaresExercise.java
+++ b/rides-and-fares/src/main/java/org/apache/flink/training/exercises/ridesandfares/RidesAndFaresExercise.java
@@ -35,19 +35,28 @@
 /**
  * The "Stateful Enrichment" exercise of the Flink training in the docs.
  *
- * The goal for this exercise is to enrich TaxiRides with fare information.
+ * <p>The goal for this exercise is to enrich TaxiRides with fare information.
  *
- * Parameters:
+ * <p>Parameters:
  * -rides path-to-input-file
  * -fares path-to-input-file
- *
  */
 public class RidesAndFaresExercise extends ExerciseBase {
+
+	/**
+	 * Main method.
+	 *
+	 * <p>Parameters:
+	 * -rides path-to-input-file
+	 * -fares path-to-input-file
+	 *
+	 * @throws Exception which occurs during job execution.
+	 */
 	public static void main(String[] args) throws Exception {
 
 		ParameterTool params = ParameterTool.fromArgs(args);
-		final String ridesFile = params.get("rides", pathToRideData);
-		final String faresFile = params.get("fares", pathToFareData);
+		final String ridesFile = params.get("rides", PATH_TO_RIDE_DATA);
+		final String faresFile = params.get("fares", PATH_TO_FARE_DATA);
 
 		final int delay = 60;					// at most 60 seconds of delay
 		final int servingSpeedFactor = 1800; 	// 30 minutes worth of events are served every second
@@ -89,4 +98,4 @@
 		public void flatMap2(TaxiFare fare, Collector<Tuple2<TaxiRide, TaxiFare>> out) throws Exception {
 		}
 	}
-}
\ No newline at end of file
+}
diff --git a/rides-and-fares/src/main/scala/org/apache/flink/training/exercises/ridesandfares/scala/RidesAndFaresExercise.scala b/rides-and-fares/src/main/scala/org/apache/flink/training/exercises/ridesandfares/scala/RidesAndFaresExercise.scala
index 8b431eb..36391d8 100644
--- a/rides-and-fares/src/main/scala/org/apache/flink/training/exercises/ridesandfares/scala/RidesAndFaresExercise.scala
+++ b/rides-and-fares/src/main/scala/org/apache/flink/training/exercises/ridesandfares/scala/RidesAndFaresExercise.scala
@@ -35,15 +35,15 @@
   * Parameters:
   * -rides path-to-input-file
   * -fares path-to-input-file
-  *
   */
 object RidesAndFaresExercise {
+
   def main(args: Array[String]) {
 
     // parse parameters
     val params = ParameterTool.fromArgs(args)
-    val ridesFile = params.get("rides", ExerciseBase.pathToRideData)
-    val faresFile = params.get("fares", ExerciseBase.pathToFareData)
+    val ridesFile = params.get("rides", ExerciseBase.PATH_TO_RIDE_DATA)
+    val faresFile = params.get("fares", ExerciseBase.PATH_TO_FARE_DATA)
 
     val delay = 60;               // at most 60 seconds of delay
     val servingSpeedFactor = 1800 // 30 minutes worth of events are served every second
diff --git a/rides-and-fares/src/solution/java/org/apache/flink/training/solutions/ridesandfares/RidesAndFaresSolution.java b/rides-and-fares/src/solution/java/org/apache/flink/training/solutions/ridesandfares/RidesAndFaresSolution.java
index 7d44fd0..961aa40 100644
--- a/rides-and-fares/src/solution/java/org/apache/flink/training/solutions/ridesandfares/RidesAndFaresSolution.java
+++ b/rides-and-fares/src/solution/java/org/apache/flink/training/solutions/ridesandfares/RidesAndFaresSolution.java
@@ -37,18 +37,28 @@
 /**
  * Java reference implementation for the "Stateful Enrichment" exercise of the Flink training in the docs.
  *
- * The goal for this exercise is to enrich TaxiRides with fare information.
+ * <p>The goal for this exercise is to enrich TaxiRides with fare information.
  *
- * Parameters:
+ * <p>Parameters:
  * -rides path-to-input-file
  * -fares path-to-input-file
  */
 public class RidesAndFaresSolution extends ExerciseBase {
+
+	/**
+	 * Main method.
+	 *
+	 * <p>Parameters:
+	 * -rides path-to-input-file
+	 * -fares path-to-input-file
+	 *
+	 * @throws Exception which occurs during job execution.
+	 */
 	public static void main(String[] args) throws Exception {
 
 		ParameterTool params = ParameterTool.fromArgs(args);
-		final String ridesFile = params.get("rides", pathToRideData);
-		final String faresFile = params.get("fares", pathToFareData);
+		final String ridesFile = params.get("rides", PATH_TO_RIDE_DATA);
+		final String faresFile = params.get("fares", PATH_TO_FARE_DATA);
 
 		final int delay = 60;					// at most 60 seconds of delay
 		final int servingSpeedFactor = 1800; 	// 30 minutes worth of events are served every second
@@ -121,4 +131,4 @@
 			}
 		}
 	}
-}
\ No newline at end of file
+}
diff --git a/rides-and-fares/src/solution/scala/org/apache/flink/training/solutions/ridesandfares/scala/RidesAndFaresSolution.scala b/rides-and-fares/src/solution/scala/org/apache/flink/training/solutions/ridesandfares/scala/RidesAndFaresSolution.scala
index e5bffe7..f6d9334 100644
--- a/rides-and-fares/src/solution/scala/org/apache/flink/training/solutions/ridesandfares/scala/RidesAndFaresSolution.scala
+++ b/rides-and-fares/src/solution/scala/org/apache/flink/training/solutions/ridesandfares/scala/RidesAndFaresSolution.scala
@@ -36,15 +36,15 @@
   * Parameters:
   * -rides path-to-input-file
   * -fares path-to-input-file
-  *
   */
 object RidesAndFaresSolution {
+
   def main(args: Array[String]) {
 
     // parse parameters
     val params = ParameterTool.fromArgs(args)
-    val ridesFile = params.get("rides", ExerciseBase.pathToRideData)
-    val faresFile = params.get("fares", ExerciseBase.pathToFareData)
+    val ridesFile = params.get("rides", ExerciseBase.PATH_TO_RIDE_DATA)
+    val faresFile = params.get("fares", ExerciseBase.PATH_TO_FARE_DATA)
 
     val delay = 60;               // at most 60 seconds of delay
     val servingSpeedFactor = 1800 // 30 minutes worth of events are served every second
diff --git a/rides-and-fares/src/test/java/org/apache/flink/training/exercises/ridesandfares/RidesAndFaresTest.java b/rides-and-fares/src/test/java/org/apache/flink/training/exercises/ridesandfares/RidesAndFaresTest.java
index 128d4b5..e1d270a 100644
--- a/rides-and-fares/src/test/java/org/apache/flink/training/exercises/ridesandfares/RidesAndFaresTest.java
+++ b/rides-and-fares/src/test/java/org/apache/flink/training/exercises/ridesandfares/RidesAndFaresTest.java
@@ -24,15 +24,15 @@
 import org.apache.flink.training.exercises.testing.TaxiRideTestBase;
 import org.apache.flink.training.solutions.ridesandfares.RidesAndFaresSolution;
 
-import com.google.common.collect.Lists;
 import org.joda.time.DateTime;
 import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.List;
+
 import static org.hamcrest.collection.IsIterableContainingInAnyOrder.containsInAnyOrder;
 import static org.junit.Assert.assertThat;
 
-import java.util.ArrayList;
-import java.util.List;
-
 public class RidesAndFaresTest extends TaxiRideTestBase<Tuple2<TaxiRide, TaxiFare>> {
 
 	static Testable javaExercise = () -> RidesAndFaresExercise.main(new String[]{});
@@ -48,7 +48,7 @@
 		TestRideSource rides = new TestRideSource(ride1, ride2);
 		TestFareSource fares = new TestFareSource(fare1, fare2);
 
-		ArrayList<Tuple2<TaxiRide, TaxiFare>> expected = Lists.newArrayList(
+		List<Tuple2<TaxiRide, TaxiFare>> expected = Arrays.asList(
 				new Tuple2<>(ride1, fare1),
 				new Tuple2<>(ride2, fare2));
 
@@ -60,7 +60,7 @@
 		TestRideSource rides = new TestRideSource(ride1, ride2);
 		TestFareSource fares = new TestFareSource(fare2, fare1);
 
-		ArrayList<Tuple2<TaxiRide, TaxiFare>> expected = Lists.newArrayList(
+		List<Tuple2<TaxiRide, TaxiFare>> expected = Arrays.asList(
 				new Tuple2<>(ride1, fare1),
 				new Tuple2<>(ride2, fare2));
 
@@ -69,7 +69,7 @@
 
 	private TaxiRide testRide(long rideId) {
 		return new TaxiRide(rideId, true, new DateTime(0), new DateTime(0),
-				0F, 0F, 0F, 0F, (short)1, 0, rideId);
+				0F, 0F, 0F, 0F, (short) 1, 0, rideId);
 	}
 
 	private TaxiFare testFare(long rideId) {
@@ -81,4 +81,4 @@
 		return runApp(rides, fares, new TestSink<>(), javaExercise, javaSolution);
 	}
 
-}
\ No newline at end of file
+}