diff --git a/lang/java/avro/src/main/java/org/apache/avro/Conversions.java b/lang/java/avro/src/main/java/org/apache/avro/Conversions.java
index 99ad500647e..2fa15eb959c 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/Conversions.java
+++ b/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);
         }
 
diff --git a/lang/java/avro/src/main/java/org/apache/avro/JsonProperties.java b/lang/java/avro/src/main/java/org/apache/avro/JsonProperties.java
index 0c100baa98f..5384b8595fc 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/JsonProperties.java
+++ b/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) {
diff --git a/lang/java/avro/src/main/java/org/apache/avro/Protocol.java b/lang/java/avro/src/main/java/org/apache/avro/Protocol.java
index 905f2778c6b..3404b93d4a5 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/Protocol.java
+++ b/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);
diff --git a/lang/java/avro/src/main/java/org/apache/avro/Resolver.java b/lang/java/avro/src/main/java/org/apache/avro/Resolver.java
index 117c9e3911f..8b62b24d757 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/Resolver.java
+++ b/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;
 
diff --git a/lang/java/avro/src/main/java/org/apache/avro/file/BZip2Codec.java b/lang/java/avro/src/main/java/org/apache/avro/file/BZip2Codec.java
index fe90557fa2e..8fd6b6a09bd 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/file/BZip2Codec.java
+++ b/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);
       }
diff --git a/lang/java/avro/src/main/java/org/apache/avro/file/DataFileConstants.java b/lang/java/avro/src/main/java/org/apache/avro/file/DataFileConstants.java
index fe269ca06b2..4664f5410df 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/file/DataFileConstants.java
+++ b/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;
 
diff --git a/lang/java/avro/src/main/java/org/apache/avro/file/DataFileStream.java b/lang/java/avro/src/main/java/org/apache/avro/file/DataFileStream.java
index aa458684635..4bf1ec5b6b1 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/file/DataFileStream.java
+++ b/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);
@@ -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;
     }
diff --git a/lang/java/avro/src/main/java/org/apache/avro/file/DataFileWriter.java b/lang/java/avro/src/main/java/org/apache/avro/file/DataFileWriter.java
index 58235da8848..c4e031b75d9 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/file/DataFileWriter.java
+++ b/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);
     }
diff --git a/lang/java/avro/src/main/java/org/apache/avro/file/DeflateCodec.java b/lang/java/avro/src/main/java/org/apache/avro/file/DeflateCodec.java
index 87498d3ee82..e6d58e46a13 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/file/DeflateCodec.java
+++ b/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;
diff --git a/lang/java/avro/src/main/java/org/apache/avro/file/FileReader.java b/lang/java/avro/src/main/java/org/apache/avro/file/FileReader.java
index 07229d59ee8..9a54cf055ef 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/file/FileReader.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/file/FileReader.java
@@ -31,7 +31,7 @@ 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.
    */
@@ -39,7 +39,7 @@ public interface FileReader<D> extends Iterator<D>, Iterable<D>, Closeable {
 
   /**
    * 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()}.
    */
diff --git a/lang/java/avro/src/main/java/org/apache/avro/file/SnappyCodec.java b/lang/java/avro/src/main/java/org/apache/avro/file/SnappyCodec.java
index 72bf0b74822..454d2925deb 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/file/SnappyCodec.java
+++ b/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;
diff --git a/lang/java/avro/src/main/java/org/apache/avro/file/XZCodec.java b/lang/java/avro/src/main/java/org/apache/avro/file/XZCodec.java
index 3052f2a4160..bc674b73466 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/file/XZCodec.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/file/XZCodec.java
@@ -26,7 +26,6 @@
 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 {
@@ -34,7 +33,7 @@ public class XZCodec 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;
@@ -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();
   }
diff --git a/lang/java/avro/src/main/java/org/apache/avro/file/ZstandardCodec.java b/lang/java/avro/src/main/java/org/apache/avro/file/ZstandardCodec.java
index f778b2fe356..0d4e31958d9 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/file/ZstandardCodec.java
+++ b/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();
   }
diff --git a/lang/java/avro/src/main/java/org/apache/avro/generic/GenericData.java b/lang/java/avro/src/main/java/org/apache/avro/generic/GenericData.java
index 362ebdc9cfc..42191bff055 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/generic/GenericData.java
+++ b/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;
diff --git a/lang/java/avro/src/main/java/org/apache/avro/generic/GenericDatumWriter.java b/lang/java/avro/src/main/java/org/apache/avro/generic/GenericDatumWriter.java
index deeac0b1f2b..20a856c4dc3 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/generic/GenericDatumWriter.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/generic/GenericDatumWriter.java
@@ -219,9 +219,7 @@ protected ClassCastException addClassCastMsg(ClassCastException e, String s) {
 
   /** Helper method for adding a message to an Avro Type Exception . */
   protected AvroTypeException addAvroTypeMsg(AvroTypeException e, String s) {
-    AvroTypeException result = new AvroTypeException(e.getMessage() + s);
-    result.initCause(e.getCause() == null ? e : e.getCause());
-    return result;
+    return new AvroTypeException(e.getMessage() + s, e.getCause() == null ? e : e.getCause());
   }
 
   /**
@@ -282,7 +280,7 @@ protected void writeArray(Schema schema, Object datum, Encoder out) throws IOExc
     long actualSize = 0;
     out.writeArrayStart();
     out.setItemCount(size);
-    for (Iterator<? extends Object> it = getArrayElements(datum); it.hasNext();) {
+    for (Iterator<?> it = getArrayElements(datum); it.hasNext();) {
       out.startItem();
       try {
         write(element, it.next(), out);
diff --git a/lang/java/avro/src/main/java/org/apache/avro/generic/PrimitivesArrays.java b/lang/java/avro/src/main/java/org/apache/avro/generic/PrimitivesArrays.java
index d34ce0f5bcb..814dd917477 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/generic/PrimitivesArrays.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/generic/PrimitivesArrays.java
@@ -58,7 +58,7 @@ public Integer get(int i) {
 
     /**
      * Direct primitive int access.
-     * 
+     *
      * @param i : index.
      * @return value at index.
      */
@@ -162,7 +162,7 @@ public Long get(int i) {
 
     /**
      * Direct primitive int access.
-     * 
+     *
      * @param i : index.
      * @return value at index.
      */
@@ -273,7 +273,7 @@ public Boolean get(int i) {
 
     /**
      * Direct primitive int access.
-     * 
+     *
      * @param i : index.
      * @return value at index.
      */
@@ -321,7 +321,7 @@ public void add(int location, boolean o) {
       size++;
       for (int index = this.size / 8; index > (location / 8); index--) {
         elements[index] <<= 1;
-        if (index > 0 && (elements[index - 1] & (1 << Byte.SIZE)) > 0) {
+        if ((elements[index - 1] & (1 << Byte.SIZE)) > 0) {
           elements[index] |= 1;
         }
       }
@@ -431,7 +431,7 @@ public Float get(int i) {
 
     /**
      * Direct primitive int access.
-     * 
+     *
      * @param i : index.
      * @return value at index.
      */
@@ -535,7 +535,7 @@ public Double get(int i) {
 
     /**
      * Direct primitive int access.
-     * 
+     *
      * @param i : index.
      * @return value at index.
      */
diff --git a/lang/java/avro/src/main/java/org/apache/avro/io/BinaryData.java b/lang/java/avro/src/main/java/org/apache/avro/io/BinaryData.java
index b6126ec236c..9ce68e9f4cf 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/io/BinaryData.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/io/BinaryData.java
@@ -255,11 +255,11 @@ private static int hashCode(HashData data, Schema schema) throws IOException {
     case UNION:
       return hashCode(data, schema.getTypes().get(decoder.readInt()));
     case FIXED:
-      return hashBytes(1, data, schema.getFixedSize(), false);
+      return hashBytes(data, schema.getFixedSize(), false);
     case STRING:
-      return hashBytes(1, data, decoder.readInt(), false);
+      return hashBytes(data, decoder.readInt(), false);
     case BYTES:
-      return hashBytes(1, data, decoder.readInt(), true);
+      return hashBytes(data, decoder.readInt(), true);
     case NULL:
       return 0;
     default:
@@ -267,8 +267,8 @@ private static int hashCode(HashData data, Schema schema) throws IOException {
     }
   }
 
-  private static int hashBytes(int init, HashData data, int len, boolean rev) throws IOException {
-    int hashCode = init;
+  private static int hashBytes(HashData data, int len, boolean rev) throws IOException {
+    int hashCode = 1;
     byte[] bytes = data.decoder.getBuf();
     int start = data.decoder.getPos();
     int end = start + len;
diff --git a/lang/java/avro/src/main/java/org/apache/avro/io/BinaryDecoder.java b/lang/java/avro/src/main/java/org/apache/avro/io/BinaryDecoder.java
index 7217be3addd..69e0186c85c 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/io/BinaryDecoder.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/io/BinaryDecoder.java
@@ -199,7 +199,7 @@ public long readLong() throws IOException {
           if (b > 0x7f) {
             // only the low 28 bits can be set, so this won't carry
             // the sign bit to the long
-            l = innerLongDecode((long) n);
+            l = innerLongDecode(n);
           } else {
             l = n;
           }
@@ -779,7 +779,7 @@ public int available() throws IOException {
   }
 
   private static class InputStreamByteSource extends ByteSource {
-    private InputStream in;
+    private final InputStream in;
     protected boolean isEof = false;
 
     private InputStreamByteSource(InputStream in) {
@@ -909,7 +909,7 @@ public void close() throws IOException {
    */
   private static class ByteArrayByteSource extends ByteSource {
     private static final int MIN_SIZE = 16;
-    private byte[] data;
+    private final byte[] data;
     private int position;
     private int max;
     private boolean compacted = false;
@@ -949,7 +949,7 @@ protected void skipSourceBytes(long length) throws IOException {
     }
 
     @Override
-    protected long trySkipBytes(long length) throws IOException {
+    protected long trySkipBytes(long length) {
       // the buffer is shared, so this should return 0
       max = ba.getLim();
       position = ba.getPos();
@@ -974,13 +974,13 @@ protected void readRaw(byte[] data, int off, int len) throws IOException {
     }
 
     @Override
-    protected int tryReadRaw(byte[] data, int off, int len) throws IOException {
+    protected int tryReadRaw(byte[] data, int off, int len) {
       // the buffer is shared, nothing to read
       return 0;
     }
 
     @Override
-    protected void compactAndFill(byte[] buf, int pos, int minPos, int remaining) throws IOException {
+    protected void compactAndFill(byte[] buf, int pos, int minPos, int remaining) {
       // this implementation does not want to mutate the array passed in,
       // so it makes a new tiny buffer unless it has been compacted once before
       if (!compacted) {
diff --git a/lang/java/avro/src/main/java/org/apache/avro/io/BlockingBinaryEncoder.java b/lang/java/avro/src/main/java/org/apache/avro/io/BlockingBinaryEncoder.java
index d0bfc8f075e..9a0d9e414b0 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/io/BlockingBinaryEncoder.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/io/BlockingBinaryEncoder.java
@@ -89,7 +89,7 @@ public enum State {
        * this case, {@link BlockedValue#start} is zero. The header for such a block
        * has _already been written_ (we've written out a header indicating that the
        * block has a single item, and we put a "zero" down for the byte-count to
-       * indicate that we don't know the physical length of the buffer. Any blocks
+       * indicate that we don't know the physical length of the buffer). Any blocks
        * _containing_ this block must be in the {@link #OVERFLOW} state.
        */
       OVERFLOW
@@ -130,7 +130,7 @@ public BlockedValue() {
      * Check invariants of <code>this</code> and also the <code>BlockedValue</code>
      * containing <code>this</code>.
      */
-    public boolean check(BlockedValue prev, int pos) {
+    public void check(BlockedValue prev, int pos) {
       assert state != State.ROOT || type == null;
       assert (state == State.ROOT || type == Schema.Type.ARRAY || type == Schema.Type.MAP);
 
@@ -156,7 +156,6 @@ public boolean check(BlockedValue prev, int pos) {
         assert prev.state == State.ROOT || prev.state == State.OVERFLOW;
         break;
       }
-      return false;
     }
   }
 
@@ -179,7 +178,7 @@ public boolean check(BlockedValue prev, int pos) {
 
   // buffer large enough for up to two ints for a block header
   // rounded up to a multiple of 4 bytes.
-  private byte[] headerBuffer = new byte[12];
+  private final byte[] headerBuffer = new byte[12];
 
   private boolean check() {
     assert buf != null;
@@ -438,7 +437,7 @@ private void endBlockedValue() throws IOException {
    * Called when we've finished writing the last item in an overflow buffer. When
    * this is finished, the top of the stack will be an empty block in the
    * "regular" state.
-   * 
+   *
    * @throws IOException
    */
   private void finishOverflow() throws IOException {
diff --git a/lang/java/avro/src/main/java/org/apache/avro/io/BlockingDirectBinaryEncoder.java b/lang/java/avro/src/main/java/org/apache/avro/io/BlockingDirectBinaryEncoder.java
index 2ef2375e640..9f391a31921 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/io/BlockingDirectBinaryEncoder.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/io/BlockingDirectBinaryEncoder.java
@@ -60,7 +60,7 @@ public class BlockingDirectBinaryEncoder extends DirectBinaryEncoder {
    * Create a writer that sends its output to the underlying stream
    * <code>out</code>.
    *
-   * @param out The Outputstream to write to
+   * @param out The OutputStream to write to
    */
   public BlockingDirectBinaryEncoder(OutputStream out) {
     super(out);
diff --git a/lang/java/avro/src/main/java/org/apache/avro/io/DirectBinaryDecoder.java b/lang/java/avro/src/main/java/org/apache/avro/io/DirectBinaryDecoder.java
index 71f3ed593af..ac251550da2 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/io/DirectBinaryDecoder.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/io/DirectBinaryDecoder.java
@@ -190,7 +190,7 @@ public InputStream inputStream() {
   }
 
   @Override
-  public boolean isEnd() throws IOException {
+  public boolean isEnd() {
     throw new UnsupportedOperationException();
   }
 }
diff --git a/lang/java/avro/src/main/java/org/apache/avro/io/EncoderFactory.java b/lang/java/avro/src/main/java/org/apache/avro/io/EncoderFactory.java
index 2039f30097a..eaa83ba8baa 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/io/EncoderFactory.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/io/EncoderFactory.java
@@ -166,7 +166,6 @@ public int getBlockSize() {
    *         <i>reuse</i> is null, this will be a new instance. If <i>reuse</i> is
    *         not null, then the returned instance may be a new instance or
    *         <i>reuse</i> reconfigured to use <i>out</i>.
-   * @throws IOException
    * @see BufferedBinaryEncoder
    * @see Encoder
    */
@@ -287,7 +286,6 @@ public BinaryEncoder blockingDirectBinaryEncoder(OutputStream out, BinaryEncoder
    *         <i>reuse</i> is null, this will be a new instance. If <i>reuse</i> is
    *         not null, then the returned instance may be a new instance or
    *         <i>reuse</i> reconfigured to use <i>out</i>.
-   * @throws IOException
    * @see BlockingBinaryEncoder
    * @see Encoder
    */
@@ -403,7 +401,7 @@ JsonEncoder jsonEncoder(Schema schema, JsonGenerator gen) throws IOException {
    * {@link ValidatingEncoder} is not thread-safe.
    *
    * @param schema  The Schema to validate operations against. Cannot be null.
-   * @param encoder The Encoder to wrap. Cannot be be null.
+   * @param encoder The Encoder to wrap. Cannot be null.
    * @return A ValidatingEncoder configured to wrap <i>encoder</i> and validate
    *         against <i>schema</i>
    * @throws IOException
diff --git a/lang/java/avro/src/main/java/org/apache/avro/io/FastReaderBuilder.java b/lang/java/avro/src/main/java/org/apache/avro/io/FastReaderBuilder.java
index f6e1ed5aae2..dfd4b4463a1 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/io/FastReaderBuilder.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/io/FastReaderBuilder.java
@@ -277,7 +277,7 @@ private FieldReader getNonConvertedReader(Action action) throws IOException {
         throw new IllegalStateException("Error getting reader for action type " + action.getClass());
       }
     case DO_NOTHING:
-      return getReaderForBaseType(action.reader, action.writer);
+      return getReaderForBaseType(action.reader);
     case RECORD:
       return createRecordReader((RecordAdjust) action);
     case ENUM:
@@ -297,7 +297,7 @@ private FieldReader getNonConvertedReader(Action action) throws IOException {
     }
   }
 
-  private FieldReader getReaderForBaseType(Schema readerSchema, Schema writerSchema) throws IOException {
+  private FieldReader getReaderForBaseType(Schema readerSchema) {
     switch (readerSchema.getType()) {
     case NULL:
       return (old, decoder) -> {
@@ -307,7 +307,7 @@ private FieldReader getReaderForBaseType(Schema readerSchema, Schema writerSchem
     case BOOLEAN:
       return (old, decoder) -> decoder.readBoolean();
     case STRING:
-      return createStringReader(readerSchema, writerSchema);
+      return createStringReader(readerSchema);
     case INT:
       return (old, decoder) -> decoder.readInt();
     case LONG:
@@ -319,7 +319,7 @@ private FieldReader getReaderForBaseType(Schema readerSchema, Schema writerSchem
     case BYTES:
       return createBytesReader();
     case FIXED:
-      return createFixedReader(readerSchema, writerSchema);
+      return createFixedReader(readerSchema);
     case RECORD: // covered by action type
     case UNION: // covered by action type
     case ENUM: // covered by action type
@@ -330,7 +330,7 @@ private FieldReader getReaderForBaseType(Schema readerSchema, Schema writerSchem
     }
   }
 
-  private FieldReader createPromotingReader(Promote promote) throws IOException {
+  private FieldReader createPromotingReader(Promote promote) {
     switch (promote.reader.getType()) {
     case BYTES:
       return (reuse, decoder) -> ByteBuffer.wrap(decoder.readString(null).getBytes());
@@ -364,7 +364,7 @@ private FieldReader createPromotingReader(Promote promote) throws IOException {
         "No promotion possible for type " + promote.writer.getType() + " to " + promote.reader.getType());
   }
 
-  private FieldReader createStringReader(Schema readerSchema, Schema writerSchema) {
+  private FieldReader createStringReader(Schema readerSchema) {
     FieldReader stringReader = createSimpleStringReader(readerSchema);
     if (isClassPropEnabled()) {
       return getTransformingStringReader(readerSchema.getProp(SpecificData.CLASS_PROP), stringReader);
@@ -497,7 +497,7 @@ private FieldReader createEnumReader(EnumAdjust action) {
     });
   }
 
-  private FieldReader createFixedReader(Schema readerSchema, Schema writerSchema) {
+  private FieldReader createFixedReader(Schema readerSchema) {
     return reusingReader((reuse, decoder) -> {
       GenericFixed fixed = (GenericFixed) data.createFixed(reuse, readerSchema);
       decoder.readFixed(fixed.bytes(), 0, readerSchema.getFixedSize());
@@ -516,9 +516,9 @@ public static FieldReader reusingReader(ReusingFieldReader reader) {
 
   public interface FieldReader extends DatumReader<Object> {
     @Override
-    public Object read(Object reuse, Decoder decoder) throws IOException;
+    Object read(Object reuse, Decoder decoder) throws IOException;
 
-    public default boolean canReuse() {
+    default boolean canReuse() {
       return false;
     }
 
@@ -530,7 +530,7 @@ default void setSchema(Schema schema) {
 
   public interface ReusingFieldReader extends FieldReader {
     @Override
-    public default boolean canReuse() {
+    default boolean canReuse() {
       return true;
     }
   }
@@ -608,7 +608,7 @@ public Object read(Object reuse, Decoder decoder) throws IOException {
   }
 
   public interface ExecutionStep {
-    public void execute(Object record, Decoder decoder) throws IOException;
+    void execute(Object record, Decoder decoder) throws IOException;
   }
 
 }
diff --git a/lang/java/avro/src/main/java/org/apache/avro/io/JsonDecoder.java b/lang/java/avro/src/main/java/org/apache/avro/io/JsonDecoder.java
index 2ad496a5b87..b4ebc050878 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/io/JsonDecoder.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/io/JsonDecoder.java
@@ -47,7 +47,7 @@
  */
 public class JsonDecoder extends ParsingDecoder implements Parser.ActionHandler {
   private JsonParser in;
-  private static JsonFactory jsonFactory = new JsonFactory();
+  private static final JsonFactory jsonFactory = new JsonFactory();
   Stack<ReorderBuffer> reorderBuffers = new Stack<>();
   ReorderBuffer currentReorderBuffer;
 
@@ -268,8 +268,7 @@ public ByteBuffer readBytes(ByteBuffer old) throws IOException {
   }
 
   private byte[] readByteArray() throws IOException {
-    byte[] result = in.getText().getBytes(StandardCharsets.ISO_8859_1);
-    return result;
+    return in.getText().getBytes(StandardCharsets.ISO_8859_1);
   }
 
   @Override
diff --git a/lang/java/avro/src/main/java/org/apache/avro/io/JsonEncoder.java b/lang/java/avro/src/main/java/org/apache/avro/io/JsonEncoder.java
index 46fb6b5cb58..50f44c0afd4 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/io/JsonEncoder.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/io/JsonEncoder.java
@@ -50,7 +50,7 @@
  * JsonEncoder is not thread-safe.
  */
 public class JsonEncoder extends ParsingEncoder implements Parser.ActionHandler {
-  private static final String LINE_SEPARATOR = System.getProperty("line.separator");
+  private static final String LINE_SEPARATOR = System.lineSeparator();
   final Parser parser;
   private JsonGenerator out;
   private boolean includeNamespace = true;
@@ -88,7 +88,7 @@ public void flush() throws IOException {
   enum JsonOptions {
     Pretty,
 
-    // Prevent underlying outputstream to be flush for optimisation purpose.
+    // Prevent underlying OutputStream to be flush for optimisation purpose.
     NoFlushStream
   }
 
@@ -98,7 +98,7 @@ private static JsonGenerator getJsonGenerator(OutputStream out, Set<JsonOptions>
     Objects.requireNonNull(out, "OutputStream cannot be null");
     JsonGenerator g = new JsonFactory().createGenerator(out, JsonEncoding.UTF8);
     if (options.contains(JsonOptions.NoFlushStream)) {
-      g = g.configure(JsonGenerator.Feature.FLUSH_PASSED_TO_STREAM, false);
+      g.configure(JsonGenerator.Feature.FLUSH_PASSED_TO_STREAM, false);
     }
     final PrettyPrinter pp;
     if (options.contains(JsonOptions.Pretty)) {
@@ -170,15 +170,13 @@ public JsonEncoder configure(OutputStream out, boolean autoflush) throws IOExcep
    * @param generator The JsonGenerator to direct output to. Cannot be null.
    * @throws IOException
    * @throws NullPointerException if {@code generator} is {@code null}
-   * @return this JsonEncoder
    */
-  private JsonEncoder configure(JsonGenerator generator) throws IOException {
+  private void configure(JsonGenerator generator) throws IOException {
     Objects.requireNonNull(generator, "JsonGenerator cannot be null");
     if (null != parser) {
       flush();
     }
     this.out = generator;
-    return this;
   }
 
   @Override
diff --git a/lang/java/avro/src/main/java/org/apache/avro/io/ValidatingEncoder.java b/lang/java/avro/src/main/java/org/apache/avro/io/ValidatingEncoder.java
index d7440c7406e..d61967751a0 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/io/ValidatingEncoder.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/io/ValidatingEncoder.java
@@ -36,7 +36,7 @@
  * and configure.
  * <p/>
  * ValidatingEncoder is not thread-safe.
- * 
+ *
  * @see Encoder
  * @see EncoderFactory
  */
@@ -44,12 +44,12 @@ public class ValidatingEncoder extends ParsingEncoder implements Parser.ActionHa
   protected Encoder out;
   protected final Parser parser;
 
-  ValidatingEncoder(Symbol root, Encoder out) throws IOException {
+  ValidatingEncoder(Symbol root, Encoder out) {
     this.out = out;
     this.parser = new Parser(root, this);
   }
 
-  ValidatingEncoder(Schema schema, Encoder in) throws IOException {
+  ValidatingEncoder(Schema schema, Encoder in) {
     this(new ValidatingGrammarGenerator().generate(schema), in);
   }
 
@@ -60,7 +60,7 @@ public void flush() throws IOException {
 
   /**
    * Reconfigures this ValidatingEncoder to wrap the encoder provided.
-   * 
+   *
    * @param encoder The Encoder to wrap for validation.
    * @return This ValidatingEncoder.
    */
diff --git a/lang/java/avro/src/main/java/org/apache/avro/io/parsing/Symbol.java b/lang/java/avro/src/main/java/org/apache/avro/io/parsing/Symbol.java
index a18f3fdbcd5..a24240978b7 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/io/parsing/Symbol.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/io/parsing/Symbol.java
@@ -94,7 +94,7 @@ static Symbol root(Symbol... symbols) {
 
   /**
    * A convenience method to construct a sequence.
-   * 
+   *
    * @param production The constituent symbols of the sequence.
    */
   static Symbol seq(Symbol... production) {
@@ -103,7 +103,7 @@ static Symbol seq(Symbol... production) {
 
   /**
    * A convenience method to construct a repeater.
-   * 
+   *
    * @param symsToRepeat The symbols to repeat in the repeater.
    */
   static Symbol repeat(Symbol endSymbol, Symbol... symsToRepeat) {
@@ -119,7 +119,7 @@ static Symbol alt(Symbol[] symbols, String[] labels) {
 
   /**
    * A convenience method to construct an ErrorAction.
-   * 
+   *
    * @param e
    */
   static Symbol error(String e) {
@@ -128,7 +128,7 @@ static Symbol error(String e) {
 
   /**
    * A convenience method to construct a ResolvingAction.
-   * 
+   *
    * @param w The writer symbol
    * @param r The reader symbol
    */
@@ -238,7 +238,7 @@ private static void copyFixups(List<Fixup> fixups, Symbol[] out, int outPos, Sym
   /**
    * Returns the amount of space required to flatten the given sub-array of
    * symbols.
-   * 
+   *
    * @param symbols The array of input symbols.
    * @param start   The index where the subarray starts.
    * @return The number of symbols that will be produced if one expands the given
@@ -317,7 +317,7 @@ public int size() {
 
     @Override
     public Iterator<Symbol> iterator() {
-      return new Iterator<Symbol>() {
+      return new Iterator<>() {
         private int pos = production.length;
 
         @Override
diff --git a/lang/java/avro/src/main/java/org/apache/avro/io/parsing/ValidatingGrammarGenerator.java b/lang/java/avro/src/main/java/org/apache/avro/io/parsing/ValidatingGrammarGenerator.java
index 7798f520ae6..2f2e9cdc1c0 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/io/parsing/ValidatingGrammarGenerator.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/io/parsing/ValidatingGrammarGenerator.java
@@ -41,7 +41,7 @@ public Symbol generate(Schema schema) {
    * given schema <tt>sc</tt>. If there is already an entry for the given schema
    * in the given map <tt>seen</tt> then that entry is returned. Otherwise a new
    * symbol is generated and an entry is inserted into the map.
-   * 
+   *
    * @param sc   The schema for which the start symbol is required
    * @param seen A map of schema to symbol mapping done so far.
    * @return The start symbol for the schema
diff --git a/lang/java/avro/src/main/java/org/apache/avro/message/RawMessageDecoder.java b/lang/java/avro/src/main/java/org/apache/avro/message/RawMessageDecoder.java
index ad2b1d31e49..917e5be88e3 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/message/RawMessageDecoder.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/message/RawMessageDecoder.java
@@ -78,9 +78,7 @@ public RawMessageDecoder(GenericData model, Schema schema) {
    * @param writeSchema the {@link Schema} used to decode buffers
    */
   public RawMessageDecoder(GenericData model, Schema writeSchema, Schema readSchema) {
-    Schema writeSchema1 = writeSchema;
-    Schema readSchema1 = readSchema;
-    this.reader = model.createDatumReader(writeSchema1, readSchema1);
+    this.reader = model.createDatumReader(writeSchema, readSchema);
   }
 
   @Override
diff --git a/lang/java/avro/src/main/java/org/apache/avro/message/RawMessageEncoder.java b/lang/java/avro/src/main/java/org/apache/avro/message/RawMessageEncoder.java
index 4df0d4c3683..230c6c1feab 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/message/RawMessageEncoder.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/message/RawMessageEncoder.java
@@ -81,9 +81,8 @@ public RawMessageEncoder(GenericData model, Schema schema) {
    * @param shouldCopy whether to copy buffers before returning encoded results
    */
   public RawMessageEncoder(GenericData model, Schema schema, boolean shouldCopy) {
-    Schema writeSchema = schema;
     this.copyOutputBytes = shouldCopy;
-    this.writer = model.createDatumWriter(writeSchema);
+    this.writer = model.createDatumWriter(schema);
   }
 
   @Override
diff --git a/lang/java/avro/src/main/java/org/apache/avro/reflect/FieldAccessReflect.java b/lang/java/avro/src/main/java/org/apache/avro/reflect/FieldAccessReflect.java
index 5d51be054be..df258f9d50d 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/reflect/FieldAccessReflect.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/reflect/FieldAccessReflect.java
@@ -40,8 +40,8 @@ protected FieldAccessor getAccessor(Field field) {
 
   private static class ReflectionBasedAccessor extends FieldAccessor {
     protected final Field field;
-    private boolean isStringable;
-    private boolean isCustomEncoded;
+    private final boolean isStringable;
+    private final boolean isCustomEncoded;
 
     public ReflectionBasedAccessor(Field field) {
       this.field = field;
@@ -105,7 +105,7 @@ protected boolean isCustomEncoded() {
 
   private static final class ReflectionBasesAccessorCustomEncoded extends ReflectionBasedAccessor {
 
-    private CustomEncoding<?> encoding;
+    private final CustomEncoding<?> encoding;
 
     public ReflectionBasesAccessorCustomEncoded(Field f, CustomEncoding<?> encoding) {
       super(f);
diff --git a/lang/java/avro/src/main/java/org/apache/avro/reflect/ReflectData.java b/lang/java/avro/src/main/java/org/apache/avro/reflect/ReflectData.java
index ab702a60e87..d4a4bec30fe 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/reflect/ReflectData.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/reflect/ReflectData.java
@@ -545,8 +545,7 @@ Schema createNonStringMapSchema(Type keyType, Type valueType, Map<String, Schema
     String name = getNameForNonStringMapRecord(keyType, valueType, keySchema, valueSchema);
     Schema elementSchema = Schema.createRecord(name, null, null, false);
     elementSchema.setFields(Arrays.asList(keyField, valueField));
-    Schema arraySchema = Schema.createArray(elementSchema);
-    return arraySchema;
+    return Schema.createArray(elementSchema);
   }
 
   /*
diff --git a/lang/java/avro/src/main/java/org/apache/avro/reflect/ReflectionUtil.java b/lang/java/avro/src/main/java/org/apache/avro/reflect/ReflectionUtil.java
index 4fa52d0345e..414535d4e96 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/reflect/ReflectionUtil.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/reflect/ReflectionUtil.java
@@ -30,7 +30,6 @@
 import java.util.IdentityHashMap;
 import java.util.Map;
 import java.util.function.Function;
-import java.util.function.Supplier;
 
 /**
  * A few utility methods for using @link{java.misc.Unsafe}, mostly for private
@@ -54,7 +53,6 @@ private ReflectionUtil() {
   static void resetFieldAccess() {
     // load only one implementation of FieldAccess
     // so it is monomorphic and the JIT can inline
-    FieldAccess access = null;
     try {
       FieldAccess reflectAccess = new FieldAccessReflect();
       if (validate(reflectAccess)) {
@@ -65,11 +63,6 @@ static void resetFieldAccess() {
     }
   }
 
-  private static <T> T load(String name, Class<T> type) throws Exception {
-    return ReflectionUtil.class.getClassLoader().loadClass(name).asSubclass(type).getDeclaredConstructor()
-        .newInstance();
-  }
-
   public static FieldAccess getFieldAccess() {
     return fieldAccess;
   }
@@ -79,8 +72,7 @@ private static boolean validate(FieldAccess access) throws Exception {
   }
 
   private static final class AccessorTestClass {
-    private boolean b = true;
-    protected byte by = 0xf;
+    private byte by = 0xf;
     public char c = 'c';
     short s = 123;
     int i = 999;
@@ -92,7 +84,7 @@ private static final class AccessorTestClass {
 
     private boolean validate(FieldAccess access) throws Exception {
       boolean valid = true;
-      valid &= validField(access, "b", b, false);
+      valid &= validField(access, "b", true, false);
       valid &= validField(access, "by", by, (byte) 0xaf);
       valid &= validField(access, "c", c, 'C');
       valid &= validField(access, "s", s, (short) 321);
@@ -149,30 +141,6 @@ private static Map<TypeVariable<?>, Type> resolveTypeVariables(Class<?> iface, M
     return reuse;
   }
 
-  private static <D> Supplier<D> getConstructorAsSupplier(Class<D> clazz) {
-    try {
-      MethodHandles.Lookup lookup = MethodHandles.lookup();
-      MethodHandle constructorHandle = lookup.findConstructor(clazz, MethodType.methodType(void.class));
-
-      CallSite site = LambdaMetafactory.metafactory(lookup, "get", MethodType.methodType(Supplier.class),
-          constructorHandle.type().generic(), constructorHandle, constructorHandle.type());
-
-      return (Supplier<D>) site.getTarget().invokeExact();
-    } catch (Throwable t) {
-      // if anything goes wrong, don't provide a Supplier
-      return null;
-    }
-  }
-
-  private static <V, R> Supplier<R> getOneArgConstructorAsSupplier(Class<R> clazz, Class<V> argumentClass, V argument) {
-    Function<V, R> supplierFunction = getConstructorAsFunction(argumentClass, clazz);
-    if (supplierFunction != null) {
-      return () -> supplierFunction.apply(argument);
-    } else {
-      return null;
-    }
-  }
-
   public static <V, R> Function<V, R> getConstructorAsFunction(Class<V> parameterClass, Class<R> clazz) {
     try {
       MethodHandles.Lookup lookup = MethodHandles.lookup();
diff --git a/lang/java/avro/src/main/java/org/apache/avro/specific/ExternalizableInput.java b/lang/java/avro/src/main/java/org/apache/avro/specific/ExternalizableInput.java
index 503db7d16fe..8fa56ae1232 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/specific/ExternalizableInput.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/specific/ExternalizableInput.java
@@ -42,11 +42,6 @@ public void close() throws IOException {
     in.close();
   }
 
-  @Override
-  public boolean markSupported() {
-    return false;
-  }
-
   @Override
   public int read() throws IOException {
     return in.read();
diff --git a/lang/java/avro/src/main/java/org/apache/avro/specific/SpecificData.java b/lang/java/avro/src/main/java/org/apache/avro/specific/SpecificData.java
index c7b5eaed8a7..def8b02fccf 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/specific/SpecificData.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/specific/SpecificData.java
@@ -619,7 +619,7 @@ public InstanceSupplier getNewRecordSupplier(Schema schema) {
 
     boolean useSchema = SchemaConstructable.class.isAssignableFrom(c);
     Constructor<?> meth = CTOR_CACHE.apply(c);
-    Object[] params = useSchema ? new Object[] { schema } : (Object[]) null;
+    Object[] params = useSchema ? new Object[] { schema } : null;
 
     return (old, sch) -> {
       try {
diff --git a/lang/java/avro/src/main/java/org/apache/avro/util/ByteBufferInputStream.java b/lang/java/avro/src/main/java/org/apache/avro/util/ByteBufferInputStream.java
index f0ae5cc8a5e..6abb62015dc 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/util/ByteBufferInputStream.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/util/ByteBufferInputStream.java
@@ -25,7 +25,7 @@
 
 /** Utility to present {@link ByteBuffer} data as an {@link InputStream}. */
 public class ByteBufferInputStream extends InputStream {
-  private List<ByteBuffer> buffers;
+  private final List<ByteBuffer> buffers;
   private int current;
 
   public ByteBufferInputStream(List<ByteBuffer> buffers) {
@@ -90,7 +90,7 @@ public ByteBuffer readBuffer(int length) throws IOException {
   /**
    * Returns the next non-empty buffer.
    */
-  private ByteBuffer getBuffer() throws IOException {
+  private ByteBuffer getBuffer() {
     while (current < buffers.size()) {
       ByteBuffer buffer = buffers.get(current);
       if (buffer.hasRemaining())