tutorials/www/stock-tracker.web-queries.xml - pivot - Git at Google

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 <document id="stock-tracker.web-queries">
     <properties>
         <title>Web Queries</title>
     </properties>

     <body>
         <p>
             "Web queries" are Pivot's native means of communicating with remote data services. They
             are designed primarily to facilitate interaction with JSON-based REST services.
             However, they are sufficiently generic to support communication with any type of
             HTTP-based service, using any data format.
         </p>

         <p>
             For example, the data presented by the Stock Tracker application is retrieved from
             Yahoo! Finance as a comma-separated value (CSV) file:
         </p>

         <p>
             <tt>"AAPL","APPLE INC",171.06,169.59,172.17,166.00,+2.88,12995693</tt><br/>
             <tt>"AMZN","AMAZON.COM INC",72.54,72.35,73.83,70.52,+1.10,2748930</tt><br/>
             <tt>"EBAY","EBAY INC",27.09,27.35,27.44,27.04,-0.02,3426369</tt><br/>
         </p>

         <p>
             This data is returned by submitting an HTTP GET request to
             <a href="http://download.finance.yahoo.com/d/quotes.csv/">http://download.finance.yahoo.com/d/quotes.csv/</a>
             with an appropriate set of query string arguments. For example, the Stock Tracker
             application passes the following arguments to the service URL:
         </p>

         <ul>
             <li>
                 <b>s</b> - A comma-separated list of stock symbols representing the quotes to
                 retrieve.
             </li>
             <li>
                 <b>f</b> - the requested format for the resulting CSV file; this is a string of
                 characters representing the various data fields returned by the query. The format
                 used by the Stock Tracker application is "snl1ohgc1v":
                 <ul>
                     <li><i>s</i> - symbol</li>
                     <li><i>n</i> - company name</li>
                     <li><i>l1</i> - most recent value</li>
                     <li><i>o</i> - opening value</li>
                     <li><i>h</i> - high value</li>
                     <li><i>g</i> - low value</li>
                     <li><i>c1</i> - change percentage</li>
                     <li><i>v</i> - volume</li>
                 </ul>
             </li>
         </ul>

         <p>
             Note that this query actually returns more data than can be displayed in the table
             view. The other data fields are used by the quote detail view, which is discussed in
             more detail in the <a href="stock-tracker.data-binding.html">data binding</a> section.
         </p>

         <h3>Constructing the Web Query</h3>

         <p>
             In order to display the stock quotes to the user, Stock Tracker must execute a web
             query to retrieve the data from the Yahoo! Finance web service and then populate the
             stock quote table view with the results of the query. The query is executed in the
             <tt>refreshTable()</tt> method, and the table is populated by a callback handler
             implemented as an anonymous inner class defined in this method. This code is defined in
             the <tt>StockTracker</tt> class.
         </p>

         <p>
             First, the web query is created:
         </p>

         <source type="java">
             <![CDATA[
             getQuery = new GetQuery(SERVICE_HOSTNAME, SERVICE_PATH);
             ]]>
         </source>

         <p>
             Then, the value of the "s" parameter is constructed by joining the values in the symbol
             list with commas, and the query arguments are applied:
         </p>

         <source type="java">
             <![CDATA[
             StringBuilder symbolsParameterBuilder = new StringBuilder();
             for (int i = 0, n = symbols.getLength(); i < n; i++) {
                 if (i > 0) {
                     symbolsParameterBuilder.append(",");
                 }

                 symbolsParameterBuilder.append(symbols.get(i));
             }

             // Format:
             // s - symbol
             // n - company name
             // l1 - most recent value
             // o - opening value
             // h - high value
             // g - low value
             // c1 - change percentage
             // v - volume
             String symbolsParameter = symbolsParameterBuilder.toString();
             getQuery.getParameters().put("s", symbolsParameter);
             getQuery.getParameters().put("f", "snl1ohgc1v");
             ]]>
         </source>

         <p>
             The resulting query URL would be similar to:
         </p>

         <p style="padding-left:24px">
             <a href="http://download.finance.yahoo.com/d/quotes.csv?s=aapl,amzn,ebay&amp;f=snl1ohgc1v">http://download.finance.yahoo.com/d/quotes.csv?s=aapl,amzn,ebay&amp;f=snl1ohgc1v</a>
         </p>

         <p>
             Next, an instance of CSVSerializer is created and configured:
         </p>

         <source type="java">
             <![CDATA[
             CSVSerializer quoteSerializer = new CSVSerializer(StockQuote.class);
             quoteSerializer.setKeys("symbol",
                 "companyName",
                 "value",
                 "openingValue",
                 "highValue",
                 "lowValue",
                 "change",
                 "volume");
             ]]>
         </source>

         <p>
             By default, the <tt>GetQuery</tt> class uses an instance of
             <tt>org.apache.pivot.core.serialization.JSONSerializer</tt> to deserialize data
             returned by a GET request. However, the quote data from Yahoo! Finance is returned as
             a CSV file; <tt>CSVSerializer</tt> is an implementation of the
             <tt>org.apache.pivot.core.serialization.Serializer</tt> interface that parses a CSV
             data stream into a sequence of name/value pairs.
         </p>

         <p>
             By default, <tt>CSVSerializer</tt> will create an instance of
             <tt>org.apache.pivot.collections.HashMap&lt;String, Object&gt;</tt> for each row it
             encounters in the CSV stream. However, a caller can specify the name of a different
             class as a constructor argument to <tt>CSVSerializer</tt>. This avoids the performance
             penalty of traversing the data twice: once to read it from the CSV stream and again to
             convert it to the appropriate type.
         </p>

         <p>
             If the item class implements the <tt>org.apache.pivot.collections.Dictionary</tt>
             interface, the parsed values are <tt>put()</tt> directly into the item instance;
             otherwise, the item is wrapped in a <tt>org.apache.pivot.beans.BeanAdapter</tt> into
             which the values are <tt>put()</tt> (<tt>BeanAdapter</tt> is a handy class that allows
             a caller to treat a Java bean object as if it were a dictionary).
         </p>

         <p>
             Stock Tracker uses the <tt>StockQuote</tt> class to represent the rows in the CSV file:
         </p>

         <source type="java">
             <![CDATA[
             public class StockQuote {
                 private String symbol = null;
                 private String companyName = null;
                 private float value = 0;
                 private float openingValue = 0;
                 private float highValue = 0;
                 private float lowValue = 0;
                 private float change = 0;
                 private float volume = 0;

                 public String getSymbol() {
                     return symbol;
                 }

                 public void setSymbol(String symbol) {
                     this.symbol = symbol;
                 }

                 public String getCompanyName() {
                     return companyName;
                 }

                 public void setCompanyName(String companyName) {
                     this.companyName = companyName;
                 }

                 public float getValue() {
                     return value;
                 }

                 public void setValue(float value) {
                     this.value = value;
                 }

                 public void setValue(String value) {
                     try {
                         setValue(Float.parseFloat(value));
                     } catch(NumberFormatException exception) {
                         setValue(Float.NaN);
                     }
                 }

                 public float getOpeningValue() {
                     return openingValue;
                 }

                 public void setOpeningValue(float openingValue) {
                     this.openingValue = openingValue;
                 }

                 public void setOpeningValue(String openingValue) {
                     try {
                         setOpeningValue(Float.parseFloat(openingValue));
                     } catch(NumberFormatException exception) {
                         setOpeningValue(Float.NaN);
                     }
                 }

                 public float getHighValue() {
                     return highValue;
                 }

                 public void setHighValue(float highValue) {
                     this.highValue = highValue;
                 }

                 public void setHighValue(String highValue) {
                     try {
                         setHighValue(Float.parseFloat(highValue));
                     } catch(NumberFormatException exception) {
                         setHighValue(Float.NaN);
                     }
                 }

                 public float getLowValue() {
                     return lowValue;
                 }

                 public void setLowValue(float lowValue) {
                     this.lowValue = lowValue;
                 }

                 public void setLowValue(String lowValue) {
                     try {
                         setLowValue(Float.parseFloat(lowValue));
                     } catch(NumberFormatException exception) {
                         setLowValue(Float.NaN);
                     }
                 }

                 public float getChange() {
                     return change;
                 }

                 public void setChange(float change) {
                     this.change = change;
                 }

                 public void setChange(String change) {
                     try {
                         setChange(Float.parseFloat(change));
                     } catch(NumberFormatException exception) {
                         setChange(Float.NaN);
                     }
                 }

                 public float getVolume() {
                     return volume;
                 }

                 public void setVolume(float volume) {
                     this.volume = volume;
                 }

                 public void setVolume(String volume) {
                     try {
                         setVolume(Float.parseFloat(volume));
                     } catch(NumberFormatException exception) {
                         setVolume(Float.NaN);
                     }
                 }
             }
             ]]>
         </source>

         <p>
             The cell renderers assigned to the columns in the BXML file ensure that the data
             represented by this class is formatted and presented correctly.
         </p>

         <p>
             Finally, the query is executed:
         </p>

         <source type="java">
             <![CDATA[
             getQuery.setSerializer(quoteSerializer);

             getQuery.execute(new TaskAdapter<Object>(new TaskListener<Object>() {
             ...
             }
             ]]>
         </source>

         <p>
             The argument passed to the <tt>execute()</tt> method is a <tt>TaskAdapter</tt> wrapped
             around an anonymous inner class implementation of <tt>TaskListener&lt;Object&gt;</tt>.
             <tt>TaskListener</tt> is an interface defined in the <tt>org.apache.pivot.util.concurrent</tt>
             package and serves as a callback handler for asynchronous operations implemented by the
             <tt>org.apache.pivot.util.concurrent.Task</tt> class, of which <tt>GetQuery</tt> is a subclass.
             <tt>TaskAdapter</tt> is defined in the <tt>pivot.wtk</tt> package and ensures that the
             callback occurs on the UI thread (otherwise, the listener is called in the context of
             the background thread, which can produce non-deterministic results).
         </p>

         <p>
             <tt>TaskListener</tt> defines two methods:
         </p>

         <p>
             <tt>public void taskExecuted(Task&lt;V&gt; task);</tt><br/>
             <tt>public void executeFailed(Task&lt;V&gt; task);</tt><br/>
         </p>

         <p>
             The template parameter <tt>V</tt> is defined by the <tt>Task</tt> class and represents
             the (optional) return value of the operation. The first method is called if the task
             completes successfully, and the second is called if the task failed for any reason.
         </p>

         <p>
             StockTracker's success handler is defined as follows:
         </p>

         <source type="java">
             <![CDATA[
                 @Override
                 public void taskExecuted(Task<Object> task) {
                     if (task == getQuery) {
                         List<Object> quotes = (List<Object>)task.getResult();

                         // Preserve any existing sort and selection
                         Sequence<?> selectedStocks = stocksTableView.getSelectedRows();

                         List<Object> tableData = (List<Object>)stocksTableView.getTableData();
                         Comparator<Object> comparator = tableData.getComparator();
                         quotes.setComparator(comparator);

                         stocksTableView.setTableData(quotes);

                         if (selectedStocks.getLength() > 0) {
                             // Select current indexes of selected stocks
                             for (int i = 0, n = selectedStocks.getLength(); i < n; i++) {
                                 Object selectedStock = selectedStocks.get(i);

                                 int index = 0;
                                 for (Object stock : stocksTableView.getTableData()) {
                                     String symbol = JSON.get(stock, "symbol");
                                     String selectedSymbol = JSON.get(selectedStock, "symbol");

                                     if (symbol.equals(selectedSymbol)) {
                                         stocksTableView.addSelectedIndex(index);
                                         break;
                                     }

                                     index++;
                                 }
                             }
                         } else {
                             if (quotes.getLength() > 0) {
                                 stocksTableView.setSelectedIndex(0);
                             }
                         }

                         refreshDetail();

                         DateFormat dateFormat = DateFormat.getDateTimeInstance(DateFormat.LONG,
                             DateFormat.MEDIUM, Locale.getDefault());
                         lastUpdateLabel.setText(dateFormat.format(new Date()));

                         getQuery = null;
                     }
                 }
             }
             ]]>
         </source>

         <p>
             If the source of the event is the currently executing task, the handler does the
             following:
         </p>

         <ul>
             <li>
                 <p>
                     Caches the current sort and selection state of the quote table view
                 </p>
             </li>
             <li>
                 <p>
                     Gets the result of the query and casts it to the appropriate type
                     (<tt>List&lt;Object&gt;</tt>)
                 </p>
             </li>
             <li>
                 <p>
                     Sets the list as the model data for the table view
                 </p>
             </li>
             <li>
                 <p>
                     Restores any selection state (which would have been lost when the model data
                     was reset)
                 </p>
             </li>
             <li>
                 <p>
                     Updates the value of the "last updated" label to reflect the current time, in
                     a manner appropriate for the current locale
                 </p>
             </li>
         </ul>

         <p>
             In the case of a failure, the handler simply logs the exception to the console:
         </p>

         <source type="java">
             <![CDATA[
             @Override
             public void executeFailed(Task<Object> task) {
                 if (task == getQuery) {
                     System.err.println(task.getFault());
                     getQuery = null;
                 }
             }
             ]]>
         </source>

         <p>
             This example demonstrates the use of <tt>GetQuery</tt> only, but Pivot also provides
             support for HTTP POST, PUT, and DELETE operations using the <tt>PostQuery</tt>,
             <tt>PutQuery</tt>, and <tt>DeleteQuery</tt> classes, respectively. This makes it very
             easy to built a complete REST client using Pivot.
         </p>
     </body>
 </document>
	<?xml version="1.0" encoding="UTF-8"?>
	<!--
	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.
	-->

	<document id="stock-tracker.web-queries">
	<properties>
	<title>Web Queries</title>
	</properties>

	<body>
	<p>
	"Web queries" are Pivot's native means of communicating with remote data services. They
	are designed primarily to facilitate interaction with JSON-based REST services.
	However, they are sufficiently generic to support communication with any type of
	HTTP-based service, using any data format.
	</p>

	<p>
	For example, the data presented by the Stock Tracker application is retrieved from
	Yahoo! Finance as a comma-separated value (CSV) file:
	</p>

	<p>
	<tt>"AAPL","APPLE INC",171.06,169.59,172.17,166.00,+2.88,12995693</tt><br/>
	<tt>"AMZN","AMAZON.COM INC",72.54,72.35,73.83,70.52,+1.10,2748930</tt><br/>
	<tt>"EBAY","EBAY INC",27.09,27.35,27.44,27.04,-0.02,3426369</tt><br/>
	</p>

	<p>
	This data is returned by submitting an HTTP GET request to
	<a href="http://download.finance.yahoo.com/d/quotes.csv/">http://download.finance.yahoo.com/d/quotes.csv/</a>
	with an appropriate set of query string arguments. For example, the Stock Tracker
	application passes the following arguments to the service URL:
	</p>

	<ul>
	<li>
	<b>s</b> - A comma-separated list of stock symbols representing the quotes to
	retrieve.
	</li>
	<li>
	<b>f</b> - the requested format for the resulting CSV file; this is a string of
	characters representing the various data fields returned by the query. The format
	used by the Stock Tracker application is "snl1ohgc1v":
	<ul>
	<li><i>s</i> - symbol</li>
	<li><i>n</i> - company name</li>
	<li><i>l1</i> - most recent value</li>
	<li><i>o</i> - opening value</li>
	<li><i>h</i> - high value</li>
	<li><i>g</i> - low value</li>
	<li><i>c1</i> - change percentage</li>
	<li><i>v</i> - volume</li>
	</ul>
	</li>
	</ul>

	<p>
	Note that this query actually returns more data than can be displayed in the table
	view. The other data fields are used by the quote detail view, which is discussed in
	more detail in the <a href="stock-tracker.data-binding.html">data binding</a> section.
	</p>

	<h3>Constructing the Web Query</h3>

	<p>
	In order to display the stock quotes to the user, Stock Tracker must execute a web
	query to retrieve the data from the Yahoo! Finance web service and then populate the
	stock quote table view with the results of the query. The query is executed in the
	<tt>refreshTable()</tt> method, and the table is populated by a callback handler
	implemented as an anonymous inner class defined in this method. This code is defined in
	the <tt>StockTracker</tt> class.
	</p>

	<p>
	First, the web query is created:
	</p>

	<source type="java">
	<![CDATA[
	getQuery = new GetQuery(SERVICE_HOSTNAME, SERVICE_PATH);
	]]>
	</source>

	<p>
	Then, the value of the "s" parameter is constructed by joining the values in the symbol
	list with commas, and the query arguments are applied:
	</p>

	<source type="java">
	<![CDATA[
	StringBuilder symbolsParameterBuilder = new StringBuilder();
	for (int i = 0, n = symbols.getLength(); i < n; i++) {
	if (i > 0) {
	symbolsParameterBuilder.append(",");
	}

	symbolsParameterBuilder.append(symbols.get(i));
	}

	// Format:
	// s - symbol
	// n - company name
	// l1 - most recent value
	// o - opening value
	// h - high value
	// g - low value
	// c1 - change percentage
	// v - volume
	String symbolsParameter = symbolsParameterBuilder.toString();
	getQuery.getParameters().put("s", symbolsParameter);
	getQuery.getParameters().put("f", "snl1ohgc1v");
	]]>
	</source>

	<p>
	The resulting query URL would be similar to:
	</p>

	<p style="padding-left:24px">
	<a href="http://download.finance.yahoo.com/d/quotes.csv?s=aapl,amzn,ebay&f=snl1ohgc1v">http://download.finance.yahoo.com/d/quotes.csv?s=aapl,amzn,ebay&f=snl1ohgc1v</a>
	</p>

	<p>
	Next, an instance of CSVSerializer is created and configured:
	</p>

	<source type="java">
	<![CDATA[
	CSVSerializer quoteSerializer = new CSVSerializer(StockQuote.class);
	quoteSerializer.setKeys("symbol",
	"companyName",
	"value",
	"openingValue",
	"highValue",
	"lowValue",
	"change",
	"volume");
	]]>
	</source>

	<p>
	By default, the <tt>GetQuery</tt> class uses an instance of
	<tt>org.apache.pivot.core.serialization.JSONSerializer</tt> to deserialize data
	returned by a GET request. However, the quote data from Yahoo! Finance is returned as
	a CSV file; <tt>CSVSerializer</tt> is an implementation of the
	<tt>org.apache.pivot.core.serialization.Serializer</tt> interface that parses a CSV
	data stream into a sequence of name/value pairs.
	</p>

	<p>
	By default, <tt>CSVSerializer</tt> will create an instance of
	<tt>org.apache.pivot.collections.HashMap<String, Object></tt> for each row it
	encounters in the CSV stream. However, a caller can specify the name of a different
	class as a constructor argument to <tt>CSVSerializer</tt>. This avoids the performance
	penalty of traversing the data twice: once to read it from the CSV stream and again to
	convert it to the appropriate type.
	</p>

	<p>
	If the item class implements the <tt>org.apache.pivot.collections.Dictionary</tt>
	interface, the parsed values are <tt>put()</tt> directly into the item instance;
	otherwise, the item is wrapped in a <tt>org.apache.pivot.beans.BeanAdapter</tt> into
	which the values are <tt>put()</tt> (<tt>BeanAdapter</tt> is a handy class that allows
	a caller to treat a Java bean object as if it were a dictionary).
	</p>

	<p>
	Stock Tracker uses the <tt>StockQuote</tt> class to represent the rows in the CSV file:
	</p>

	<source type="java">
	<![CDATA[
	public class StockQuote {
	private String symbol = null;
	private String companyName = null;
	private float value = 0;
	private float openingValue = 0;
	private float highValue = 0;
	private float lowValue = 0;
	private float change = 0;
	private float volume = 0;

	public String getSymbol() {
	return symbol;
	}

	public void setSymbol(String symbol) {
	this.symbol = symbol;
	}

	public String getCompanyName() {
	return companyName;
	}

	public void setCompanyName(String companyName) {
	this.companyName = companyName;
	}

	public float getValue() {
	return value;
	}

	public void setValue(float value) {
	this.value = value;
	}

	public void setValue(String value) {
	try {
	setValue(Float.parseFloat(value));
	} catch(NumberFormatException exception) {
	setValue(Float.NaN);
	}
	}

	public float getOpeningValue() {
	return openingValue;
	}

	public void setOpeningValue(float openingValue) {
	this.openingValue = openingValue;
	}

	public void setOpeningValue(String openingValue) {
	try {
	setOpeningValue(Float.parseFloat(openingValue));
	} catch(NumberFormatException exception) {
	setOpeningValue(Float.NaN);
	}
	}

	public float getHighValue() {
	return highValue;
	}

	public void setHighValue(float highValue) {
	this.highValue = highValue;
	}

	public void setHighValue(String highValue) {
	try {
	setHighValue(Float.parseFloat(highValue));
	} catch(NumberFormatException exception) {
	setHighValue(Float.NaN);
	}
	}

	public float getLowValue() {
	return lowValue;
	}

	public void setLowValue(float lowValue) {
	this.lowValue = lowValue;
	}

	public void setLowValue(String lowValue) {
	try {
	setLowValue(Float.parseFloat(lowValue));
	} catch(NumberFormatException exception) {
	setLowValue(Float.NaN);
	}
	}

	public float getChange() {
	return change;
	}

	public void setChange(float change) {
	this.change = change;
	}

	public void setChange(String change) {
	try {
	setChange(Float.parseFloat(change));
	} catch(NumberFormatException exception) {
	setChange(Float.NaN);
	}
	}

	public float getVolume() {
	return volume;
	}

	public void setVolume(float volume) {
	this.volume = volume;
	}

	public void setVolume(String volume) {
	try {
	setVolume(Float.parseFloat(volume));
	} catch(NumberFormatException exception) {
	setVolume(Float.NaN);
	}
	}
	}
	]]>
	</source>

	<p>
	The cell renderers assigned to the columns in the BXML file ensure that the data
	represented by this class is formatted and presented correctly.
	</p>

	<p>
	Finally, the query is executed:
	</p>

	<source type="java">
	<![CDATA[
	getQuery.setSerializer(quoteSerializer);

	getQuery.execute(new TaskAdapter<Object>(new TaskListener<Object>() {
	...
	}
	]]>
	</source>

	<p>
	The argument passed to the <tt>execute()</tt> method is a <tt>TaskAdapter</tt> wrapped
	around an anonymous inner class implementation of <tt>TaskListener<Object></tt>.
	<tt>TaskListener</tt> is an interface defined in the <tt>org.apache.pivot.util.concurrent</tt>
	package and serves as a callback handler for asynchronous operations implemented by the
	<tt>org.apache.pivot.util.concurrent.Task</tt> class, of which <tt>GetQuery</tt> is a subclass.
	<tt>TaskAdapter</tt> is defined in the <tt>pivot.wtk</tt> package and ensures that the
	callback occurs on the UI thread (otherwise, the listener is called in the context of
	the background thread, which can produce non-deterministic results).
	</p>

	<p>
	<tt>TaskListener</tt> defines two methods:
	</p>

	<p>
	<tt>public void taskExecuted(Task<V> task);</tt><br/>
	<tt>public void executeFailed(Task<V> task);</tt><br/>
	</p>

	<p>
	The template parameter <tt>V</tt> is defined by the <tt>Task</tt> class and represents
	the (optional) return value of the operation. The first method is called if the task
	completes successfully, and the second is called if the task failed for any reason.
	</p>

	<p>
	StockTracker's success handler is defined as follows:
	</p>

	<source type="java">
	<![CDATA[
	@Override
	public void taskExecuted(Task<Object> task) {
	if (task == getQuery) {
	List<Object> quotes = (List<Object>)task.getResult();

	// Preserve any existing sort and selection
	Sequence<?> selectedStocks = stocksTableView.getSelectedRows();

	List<Object> tableData = (List<Object>)stocksTableView.getTableData();
	Comparator<Object> comparator = tableData.getComparator();
	quotes.setComparator(comparator);

	stocksTableView.setTableData(quotes);

	if (selectedStocks.getLength() > 0) {
	// Select current indexes of selected stocks
	for (int i = 0, n = selectedStocks.getLength(); i < n; i++) {
	Object selectedStock = selectedStocks.get(i);

	int index = 0;
	for (Object stock : stocksTableView.getTableData()) {
	String symbol = JSON.get(stock, "symbol");
	String selectedSymbol = JSON.get(selectedStock, "symbol");

	if (symbol.equals(selectedSymbol)) {
	stocksTableView.addSelectedIndex(index);
	break;
	}

	index++;
	}
	}
	} else {
	if (quotes.getLength() > 0) {
	stocksTableView.setSelectedIndex(0);
	}
	}

	refreshDetail();

	DateFormat dateFormat = DateFormat.getDateTimeInstance(DateFormat.LONG,
	DateFormat.MEDIUM, Locale.getDefault());
	lastUpdateLabel.setText(dateFormat.format(new Date()));

	getQuery = null;
	}
	}
	}
	]]>
	</source>

	<p>
	If the source of the event is the currently executing task, the handler does the
	following:
	</p>

	<ul>
	<li>
	<p>
	Caches the current sort and selection state of the quote table view
	</p>
	</li>
	<li>
	<p>
	Gets the result of the query and casts it to the appropriate type
	(<tt>List<Object></tt>)
	</p>
	</li>
	<li>
	<p>
	Sets the list as the model data for the table view
	</p>
	</li>
	<li>
	<p>
	Restores any selection state (which would have been lost when the model data
	was reset)
	</p>
	</li>
	<li>
	<p>
	Updates the value of the "last updated" label to reflect the current time, in
	a manner appropriate for the current locale
	</p>
	</li>
	</ul>

	<p>
	In the case of a failure, the handler simply logs the exception to the console:
	</p>

	<source type="java">
	<![CDATA[
	@Override
	public void executeFailed(Task<Object> task) {
	if (task == getQuery) {
	System.err.println(task.getFault());
	getQuery = null;
	}
	}
	]]>
	</source>

	<p>
	This example demonstrates the use of <tt>GetQuery</tt> only, but Pivot also provides
	support for HTTP POST, PUT, and DELETE operations using the <tt>PostQuery</tt>,
	<tt>PutQuery</tt>, and <tt>DeleteQuery</tt> classes, respectively. This makes it very
	easy to built a complete REST client using Pivot.
	</p>
	</body>
	</document>