AVRO-4068: Java Code Cleanup

lang/java/avro/src/main/java/org/apache/avro/Conversions.java

@@ -192,7 +192,7 @@ public BigDecimal fromBytes(final ByteBuffer value, final Schema schema, final L
         BigInteger bg = null;
         ByteBuffer buffer = decoder.readBytes(null);
         byte[] array = buffer.array();
-        if (array != null && array.length > 0) {
+        if (array.length > 0) {
           bg = new BigInteger(array);
         }
 

lang/java/avro/src/main/java/org/apache/avro/JsonProperties.java

@@ -150,9 +150,9 @@ private Null() {
   // Also, we only ever ADD to the collection, never changing a value, so
   // putWithAbsent is the
   // only modifier
-  private ConcurrentMap<String, JsonNode> props = new ConcurrentHashMap<String, JsonNode>() {
+  private final ConcurrentMap<String, JsonNode> props = new ConcurrentHashMap<>() {
     private static final long serialVersionUID = 1L;
-    private Queue<MapEntry<String, JsonNode>> propOrder = new ConcurrentLinkedQueue<>();
+    private final Queue<MapEntry<String, JsonNode>> propOrder = new ConcurrentLinkedQueue<>();
 
     @Override
     public JsonNode putIfAbsent(String key, JsonNode value) {
@@ -170,10 +170,10 @@ public JsonNode put(String key, JsonNode value) {
 
     @Override
     public Set<Map.Entry<String, JsonNode>> entrySet() {
-      return new AbstractSet<Map.Entry<String, JsonNode>>() {
+      return new AbstractSet<>() {
         @Override
         public Iterator<Map.Entry<String, JsonNode>> iterator() {
-          return new Iterator<Map.Entry<String, JsonNode>>() {
+          return new Iterator<>() {
             Iterator<MapEntry<String, JsonNode>> it = propOrder.iterator();
 
             @Override
@@ -196,7 +196,7 @@ public int size() {
     }
   };
 
-  private Set<String> reserved;
+  private final Set<String> reserved;
 
   JsonProperties(Set<String> reserved) {
     this.reserved = reserved;
@@ -206,7 +206,7 @@ public int size() {
     this.reserved = reserved;
     for (Entry<String, ?> a : propMap.entrySet()) {
       Object v = a.getValue();
-      JsonNode json = null;
+      JsonNode json;
       if (v instanceof String) {
         json = TextNode.valueOf((String) v);
       } else if (v instanceof JsonNode) {

lang/java/avro/src/main/java/org/apache/avro/Protocol.java

@@ -25,7 +25,6 @@
 import java.nio.charset.StandardCharsets;
 import java.security.MessageDigest;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashSet;
@@ -71,11 +70,9 @@ public class Protocol extends JsonProperties {
   public static final long VERSION = 1;
 
   // Support properties for both Protocol and Message objects
-  private static final Set<String> MESSAGE_RESERVED = Collections
-      .unmodifiableSet(new HashSet<>(Arrays.asList("doc", "response", "request", "errors", "one-way")));
+  private static final Set<String> MESSAGE_RESERVED = Set.of("doc", "response", "request", "errors", "one-way");
 
-  private static final Set<String> FIELD_RESERVED = Collections
-      .unmodifiableSet(new HashSet<>(Arrays.asList("name", "type", "doc", "default", "aliases")));
+  private static final Set<String> FIELD_RESERVED = Set.of("name", "type", "doc", "default", "aliases");
 
   /** A protocol message. */
   public class Message extends JsonProperties {
@@ -255,8 +252,8 @@ void toJson1(Set<String> knownNames, JsonGenerator gen) throws IOException {
   /** Union type for generating system errors. */
   public static final Schema SYSTEM_ERRORS = Schema.createUnion(Collections.singletonList(SYSTEM_ERROR));
 
-  private static final Set<String> PROTOCOL_RESERVED = Collections
-      .unmodifiableSet(new HashSet<>(Arrays.asList("namespace", "protocol", "doc", "messages", "types", "errors")));
+  private static final Set<String> PROTOCOL_RESERVED = Set.of("namespace", "protocol", "doc", "messages", "types",
+      "errors");
 
   private Protocol() {
     super(PROTOCOL_RESERVED);

lang/java/avro/src/main/java/org/apache/avro/Resolver.java

@@ -435,7 +435,7 @@ public static class RecordAdjust extends Action {
      * fields that will be read from the writer: these <i>n</i> are in the order
      * dictated by writer's schema. The remaining <i>m</i> fields will be read from
      * default values (actions for these default values are found in
-     * {@link RecordAdjust#defaults}.
+     * {@link RecordAdjust#defaults}).
      */
     public final Field[] readerOrder;
 

lang/java/avro/src/main/java/org/apache/avro/file/BZip2Codec.java

@@ -64,7 +64,7 @@ public ByteBuffer decompress(ByteBuffer compressedData) throws IOException {
 
     try (BZip2CompressorInputStream inputStream = new BZip2CompressorInputStream(bais)) {
 
-      int readCount = -1;
+      int readCount;
       while ((readCount = inputStream.read(buffer, compressedData.position(), buffer.length)) > 0) {
         baos.write(buffer, 0, readCount);
       }

lang/java/avro/src/main/java/org/apache/avro/file/DataFileConstants.java

@@ -27,7 +27,6 @@ private DataFileConstants() {
 
   public static final byte VERSION = 1;
   public static final byte[] MAGIC = new byte[] { (byte) 'O', (byte) 'b', (byte) 'j', VERSION };
-  public static final long FOOTER_BLOCK = -1;
   public static final int SYNC_SIZE = 16;
   public static final int DEFAULT_SYNC_INTERVAL = 4000 * SYNC_SIZE;
 

lang/java/avro/src/main/java/org/apache/avro/file/DataFileStream.java

@@ -63,7 +63,7 @@ private Header() {
     }
   }
 
-  private DatumReader<D> reader;
+  private final DatumReader<D> reader;
   private long blockSize;
   private boolean availableBlock = false;
   private Header header;
@@ -94,7 +94,7 @@ public DataFileStream(InputStream in, DatumReader<D> reader) throws IOException
   /**
    * create an uninitialized DataFileStream
    */
-  protected DataFileStream(DatumReader<D> reader) throws IOException {
+  protected DataFileStream(DatumReader<D> reader) {
     this.reader = reader;
   }
 
@@ -147,7 +147,7 @@ void initialize(InputStream in, byte[] magic) throws IOException {
   }
 
   /** Initialize the stream without reading from it. */
-  void initialize(Header header) throws IOException {
+  void initialize(Header header) {
     this.header = header;
     this.codec = resolveCodec();
     reader.setSchema(header.schema);
@@ -303,7 +303,7 @@ boolean hasNextBlock() {
       blockRemaining = vin.readLong(); // read block count
       blockSize = vin.readLong(); // read block size
       if (blockSize > Integer.MAX_VALUE || blockSize < 0) {
-        throw new IOException("Block size invalid or too large for this " + "implementation: " + blockSize);
+        throw new IOException("Block size invalid or too large for this implementation: " + blockSize);
       }
       blockCount = blockRemaining;
       availableBlock = true;
@@ -366,22 +366,6 @@ private DataBlock(long numEntries, int blockSize) {
       this.numEntries = numEntries;
     }
 
-    byte[] getData() {
-      return data;
-    }
-
-    long getNumEntries() {
-      return numEntries;
-    }
-
-    int getBlockSize() {
-      return blockSize;
-    }
-
-    boolean isFlushOnWrite() {
-      return flushOnWrite;
-    }
-
     void setFlushOnWrite(boolean flushOnWrite) {
       this.flushOnWrite = flushOnWrite;
     }

lang/java/avro/src/main/java/org/apache/avro/file/DataFileWriter.java

@@ -25,7 +25,7 @@
 import org.apache.avro.io.DatumWriter;
 import org.apache.avro.io.EncoderFactory;
 import org.apache.avro.util.NonCopyingByteArrayOutputStream;
-import org.apache.commons.compress.utils.IOUtils;
+import org.apache.commons.io.IOUtils;
 
 import java.io.BufferedOutputStream;
 import java.io.Closeable;
@@ -56,7 +56,7 @@
  */
 public class DataFileWriter<D> implements Closeable, Flushable {
   private Schema schema;
-  private DatumWriter<D> dout;
+  private final DatumWriter<D> dout;
 
   private OutputStream underlyingStream;
 
@@ -117,11 +117,10 @@ public DataFileWriter<D> setCodec(CodecFactory c) {
    * is written. In this case, the {@linkplain #flush()} must be called to flush
    * the stream.
    *
-   * Invalid values throw IllegalArgumentException
-   *
    * @param syncInterval the approximate number of uncompressed bytes to write in
    *                     each block
    * @return this DataFileWriter
+   * @throws IllegalArgumentException if syncInterval is invalid
    */
   public DataFileWriter<D> setSyncInterval(int syncInterval) {
     if (syncInterval < 32 || syncInterval > (1 << 30)) {
@@ -193,7 +192,7 @@ public DataFileWriter<D> create(Schema schema, OutputStream outs, byte[] sync) t
    * Set whether this writer should flush the block to the stream every time a
    * sync marker is written. By default, the writer will flush the buffer each
    * time a sync marker is written (if the block size limit is reached or the
-   * {@linkplain #sync()} is called.
+   * {@linkplain #sync()} is called).
    *
    * @param flushOnEveryBlock - If set to false, this writer will not flush the
    *                          block to the stream until {@linkplain #flush()} is
@@ -475,11 +474,11 @@ public void close() throws IOException {
     }
   }
 
-  private class BufferedFileOutputStream extends BufferedOutputStream {
+  private static class BufferedFileOutputStream extends BufferedOutputStream {
     private long position; // start of buffer
 
     private class PositionFilter extends FilterOutputStream {
-      public PositionFilter(OutputStream out) throws IOException {
+      public PositionFilter(OutputStream out) {
         super(out);
       }
 
@@ -490,7 +489,7 @@ public void write(byte[] b, int off, int len) throws IOException {
       }
     }
 
-    public BufferedFileOutputStream(OutputStream out) throws IOException {
+    public BufferedFileOutputStream(OutputStream out) {
       super(null);
       this.out = new PositionFilter(out);
     }

lang/java/avro/src/main/java/org/apache/avro/file/DeflateCodec.java

@@ -40,7 +40,7 @@ public class DeflateCodec extends Codec {
   private static final int DEFAULT_BUFFER_SIZE = 8192;
 
   static class Option extends CodecFactory {
-    private int compressionLevel;
+    private final int compressionLevel;
 
     Option(int compressionLevel) {
       this.compressionLevel = compressionLevel;
@@ -55,8 +55,8 @@ protected Codec createInstance() {
   private Deflater deflater;
   private Inflater inflater;
   // currently only do 'nowrap' -- RFC 1951, not zlib
-  private boolean nowrap = true;
-  private int compressionLevel;
+  private final boolean nowrap = true;
+  private final int compressionLevel;
 
   public DeflateCodec(int compressionLevel) {
     this.compressionLevel = compressionLevel;

lang/java/avro/src/main/java/org/apache/avro/file/FileReader.java

@@ -31,15 +31,15 @@ public interface FileReader<D> extends Iterator<D>, Iterable<D>, Closeable {
 
   /**
    * Read the next datum from the file.
-   * 
+   *
    * @param reuse an instance to reuse.
    * @throws NoSuchElementException if no more remain in the file.
    */
   D next(D reuse) throws IOException;
 
   /**
    * Move to the next synchronization point after a position. To process a range
-   * of file entires, call this with the starting position, then check
+   * of file entries, call this with the starting position, then check
    * {@link #pastSync(long)} with the end point before each call to
    * {@link #next()}.
    */

lang/java/avro/src/main/java/org/apache/avro/file/SnappyCodec.java

@@ -26,7 +26,7 @@
 
 /** * Implements Snappy compression and decompression. */
 public class SnappyCodec extends Codec {
-  private CRC32 crc32 = new CRC32();
+  private final CRC32 crc32 = new CRC32();
 
   static class Option extends CodecFactory {
     static {
@@ -72,7 +72,7 @@ public ByteBuffer decompress(ByteBuffer in) throws IOException {
 
     crc32.reset();
     crc32.update(out.array(), 0, size);
-    if (in.getInt(((Buffer) in).limit() - 4) != (int) crc32.getValue())
+    if (in.getInt(in.limit() - 4) != (int) crc32.getValue())
       throw new IOException("Checksum failure");
 
     return out;

lang/java/avro/src/main/java/org/apache/avro/file/XZCodec.java

@@ -26,15 +26,14 @@
 import org.apache.avro.util.NonCopyingByteArrayOutputStream;
 import org.apache.commons.compress.compressors.xz.XZCompressorInputStream;
 import org.apache.commons.compress.compressors.xz.XZCompressorOutputStream;
-import org.apache.commons.compress.utils.IOUtils;
 
 /** * Implements xz compression and decompression. */
 public class XZCodec extends Codec {
   public final static int DEFAULT_COMPRESSION = 6;
   private static final int DEFAULT_BUFFER_SIZE = 8192;
 
   static class Option extends CodecFactory {
-    private int compressionLevel;
+    private final int compressionLevel;
 
     Option(int compressionLevel) {
       this.compressionLevel = compressionLevel;
@@ -46,7 +45,7 @@ protected Codec createInstance() {
     }
   }
 
-  private int compressionLevel;
+  private final int compressionLevel;
 
   public XZCodec(int compressionLevel) {
     this.compressionLevel = compressionLevel;
@@ -72,7 +71,7 @@ public ByteBuffer decompress(ByteBuffer data) throws IOException {
     InputStream bytesIn = new ByteArrayInputStream(data.array(), computeOffset(data), data.remaining());
 
     try (InputStream ios = new XZCompressorInputStream(bytesIn)) {
-      IOUtils.copy(ios, baos);
+      ios.transferTo(baos);
     }
     return baos.asByteBuffer();
   }

lang/java/avro/src/main/java/org/apache/avro/file/ZstandardCodec.java

@@ -24,7 +24,6 @@
 import java.nio.ByteBuffer;
 
 import org.apache.avro.util.NonCopyingByteArrayOutputStream;
-import org.apache.commons.compress.utils.IOUtils;
 
 public class ZstandardCodec extends Codec {
   public final static int DEFAULT_COMPRESSION = 3;
@@ -82,7 +81,7 @@ public ByteBuffer decompress(ByteBuffer compressedData) throws IOException {
     InputStream bytesIn = new ByteArrayInputStream(compressedData.array(), computeOffset(compressedData),
         compressedData.remaining());
     try (InputStream ios = ZstandardLoader.input(bytesIn, useBufferPool)) {
-      IOUtils.copy(ios, baos);
+      ios.transferTo(baos);
     }
     return baos.asByteBuffer();
   }

lang/java/avro/src/main/java/org/apache/avro/generic/GenericData.java

@@ -137,9 +137,9 @@ private void loadConversions() {
     }
   }
 
-  private Map<String, Conversion<?>> conversions = new HashMap<>();
+  private final Map<String, Conversion<?>> conversions = new HashMap<>();
 
-  private Map<Class<?>, Map<String, Conversion<?>>> conversionsByClass = new IdentityHashMap<>();
+  private final Map<Class<?>, Map<String, Conversion<?>>> conversionsByClass = new IdentityHashMap<>();
 
   public Collection<Conversion<?>> getConversions() {
     return conversions.values();
@@ -364,7 +364,7 @@ public int hashCode() {
 
     @Override
     public Iterator<T> iterator() {
-      return new Iterator<T>() {
+      return new Iterator<>() {
         private int position = 0;
 
         @Override
@@ -551,8 +551,8 @@ public int compareTo(Fixed that) {
 
   /** Default implementation of {@link GenericEnumSymbol}. */
   public static class EnumSymbol implements GenericEnumSymbol<EnumSymbol> {
-    private Schema schema;
-    private String symbol;
+    private final Schema schema;
+    private final String symbol;
 
     public EnumSymbol(Schema schema, String symbol) {
       this.schema = schema;
@@ -1259,9 +1259,7 @@ protected int compareMaps(final Map<?, ?> m1, final Map<?, ?> m2) {
           }
         }
       }
-    } catch (ClassCastException unused) {
-      return 1;
-    } catch (NullPointerException unused) {
+    } catch (ClassCastException | NullPointerException unused) {
       return 1;
     }
 

lang/java/avro/src/main/java/org/apache/avro/generic/GenericDatumReader.java

@@ -519,7 +519,7 @@ public int hashCode() {
 
     @Override
     public boolean equals(Object obj) {
-      if (obj == null || !(obj instanceof GenericDatumReader.IdentitySchemaKey)) {
+      if (!(obj instanceof GenericDatumReader.IdentitySchemaKey)) {
         return false;
       }
       IdentitySchemaKey key = (IdentitySchemaKey) obj;