minor updates

Author: chenjunjiedada

parquet-column/src/main/java/org/apache/parquet/column/impl/ColumnWriterBase.java

@@ -58,8 +58,8 @@ abstract class ColumnWriterBase implements ColumnWriter {
   private long rowsWrittenSoFar = 0;
   private int pageRowCount;
 
-  private BloomFilterWriter bloomFilterWriter;
-  private BloomFilter bloomFilter;
+  private final BloomFilterWriter bloomFilterWriter;
+  private final BloomFilter bloomFilter;
 
   ColumnWriterBase(
       ColumnDescriptor path,
@@ -72,6 +72,8 @@ abstract class ColumnWriterBase implements ColumnWriter {
     this.repetitionLevelColumn = createRLWriter(props, path);
     this.definitionLevelColumn = createDLWriter(props, path);
     this.dataColumn = props.newValuesWriter(path);
+    this.bloomFilter = null;
+    this.bloomFilterWriter = null;
   }
 
   ColumnWriterBase(

parquet-column/src/test/java/org/apache/parquet/column/values/bloomfilter/TestBlockSplitBloomFilter.java

@@ -79,7 +79,7 @@ public void testBloomFilterForPrimitives() {
   private void testBloomFilterForPrimitives(long seed) {
     Random random = new Random(seed);
     final int numValues = 1024 * 1024;
-    final int numBytes = BlockSplitBloomFilter.optimalNumOfBits(numValues , random.nextDouble()/10) / 8;
+    final int numBytes = BlockSplitBloomFilter.optimalNumOfBits(numValues , random.nextDouble() / 10) / 8;
     BloomFilter bloomFilter = new BlockSplitBloomFilter(numBytes);
 
     Set<Object> values = new HashSet<>();