PARQUET-1743: Add equals method to the BloomFilter (#731)

diff --git a/parquet-column/src/main/java/org/apache/parquet/column/values/bloomfilter/BlockSplitBloomFilter.java b/parquet-column/src/main/java/org/apache/parquet/column/values/bloomfilter/BlockSplitBloomFilter.java
index cc9f674..043c40e 100644
--- a/parquet-column/src/main/java/org/apache/parquet/column/values/bloomfilter/BlockSplitBloomFilter.java
+++ b/parquet-column/src/main/java/org/apache/parquet/column/values/bloomfilter/BlockSplitBloomFilter.java

@@ -28,6 +28,7 @@
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.nio.IntBuffer;
+import java.util.Arrays;
 
 /*
  * This Bloom filter is implemented using block-based Bloom filter algorithm from Putze et al.'s
@@ -356,4 +357,18 @@
   public long hash(Binary value) {
     return hashFunction.hashBytes(value.getBytes());
   }
+
+  @Override
+  public boolean equals(Object object) {
+    if (object == this) {
+      return true;
+    }
+    if (object instanceof BlockSplitBloomFilter) {
+      BlockSplitBloomFilter that = (BlockSplitBloomFilter) object;
+      return Arrays.equals(this.bitset, that.bitset)
+        && this.maximumBytes == that.maximumBytes
+        && this.hashStrategy == that.hashStrategy;
+    }
+    return false;
+  }
 }

diff --git a/parquet-column/src/main/java/org/apache/parquet/column/values/bloomfilter/BloomFilter.java b/parquet-column/src/main/java/org/apache/parquet/column/values/bloomfilter/BloomFilter.java
index 8b26c97..f1f5897 100644
--- a/parquet-column/src/main/java/org/apache/parquet/column/values/bloomfilter/BloomFilter.java
+++ b/parquet-column/src/main/java/org/apache/parquet/column/values/bloomfilter/BloomFilter.java

@@ -94,6 +94,14 @@
   long getBitsetSize();
 
   /**
+   * Compare this Bloom filter to the specified object.
+   *
+   * @param object
+   * @return true if the given object represents a Bloom filter equivalent to this Bloom filter, false otherwise.
+   */
+  boolean equals(Object object);
+
+  /**
    * Compute hash for int value by using its plain encoding result.
    *
    * @param value the value to hash

diff --git a/parquet-column/src/test/java/org/apache/parquet/column/values/bloomfilter/TestBlockSplitBloomFilter.java b/parquet-column/src/test/java/org/apache/parquet/column/values/bloomfilter/TestBlockSplitBloomFilter.java
index d75c0e2..1017302 100644
--- a/parquet-column/src/test/java/org/apache/parquet/column/values/bloomfilter/TestBlockSplitBloomFilter.java
+++ b/parquet-column/src/test/java/org/apache/parquet/column/values/bloomfilter/TestBlockSplitBloomFilter.java

@@ -34,6 +34,7 @@
 import org.junit.rules.TemporaryFolder;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.assertNotEquals;
 
 public class TestBlockSplitBloomFilter {
   @Test
@@ -94,6 +95,25 @@
   }
 
   @Test
+  public void testEquals() {
+    final String[] words = {"hello", "parquet", "bloom", "filter"};
+    BloomFilter bloomFilterOne = new BlockSplitBloomFilter(1024);
+    BloomFilter bloomFilterTwo = new BlockSplitBloomFilter(1024);
+
+    for (String word : words) {
+      bloomFilterOne.insertHash(bloomFilterOne.hash(Binary.fromString(word)));
+      bloomFilterTwo.insertHash(bloomFilterTwo.hash(Binary.fromString(word)));
+    }
+
+    assertEquals(bloomFilterOne, bloomFilterTwo);
+
+    BloomFilter bloomFilterThree = new BlockSplitBloomFilter(1024);
+    bloomFilterThree.insertHash(bloomFilterThree.hash(Binary.fromString("parquet")));
+
+    assertNotEquals(bloomFilterTwo, bloomFilterThree);
+  }
+
+  @Test
   public void testFPP() throws IOException {
     final int totalCount = 100000;
     final double FPP = 0.01;