HBASE-23308: Review of NullPointerExceptions (#836)

Signed-off-by: stack <stack@apache.org>

hbase-backup/src/main/java/org/apache/hadoop/hbase/backup/BackupDriver.java

@@ -40,6 +40,7 @@
 
 import java.io.IOException;
 import java.net.URI;
+import java.util.Objects;
 
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.Path;
@@ -187,10 +188,7 @@ public static void main(String[] args) throws Exception {
 
   @Override
   public int run(String[] args) throws IOException {
-    if (conf == null) {
-      LOG.error("Tool configuration is not initialized");
-      throw new NullPointerException("conf");
-    }
+    Objects.requireNonNull(conf, "Tool configuration is not initialized");
 
     CommandLine cmd;
     try {

hbase-backup/src/main/java/org/apache/hadoop/hbase/backup/RestoreDriver.java

@@ -35,6 +35,7 @@
 import java.io.IOException;
 import java.net.URI;
 import java.util.List;
+import java.util.Objects;
 
 import org.apache.commons.lang3.StringUtils;
 import org.apache.hadoop.conf.Configuration;
@@ -232,10 +233,7 @@ public static void main(String[] args) throws Exception {
 
   @Override
   public int run(String[] args) {
-    if (conf == null) {
-      LOG.error("Tool configuration is not initialized");
-      throw new NullPointerException("conf");
-    }
+    Objects.requireNonNull(conf, "Tool configuration is not initialized");
 
     CommandLine cmd;
     try {

hbase-client/src/main/java/org/apache/hadoop/hbase/MetaTableAccessor.java

@@ -31,6 +31,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.NavigableMap;
+import java.util.Objects;
 import java.util.Set;
 import java.util.SortedMap;
 import java.util.regex.Matcher;
@@ -230,13 +231,13 @@ private static List<Result> fullScan(Connection connection, QueryType type) thro
    * Callers should call close on the returned {@link Table} instance.
    * @param connection connection we're using to access Meta
    * @return An {@link Table} for <code>hbase:meta</code>
+   * @throws NullPointerException if {@code connection} is {@code null}
    */
   public static Table getMetaHTable(final Connection connection)
   throws IOException {
     // We used to pass whole CatalogTracker in here, now we just pass in Connection
-    if (connection == null) {
-      throw new NullPointerException("No connection");
-    } else if (connection.isClosed()) {
+    Objects.requireNonNull(connection, "Connection cannot be null");
+    if (connection.isClosed()) {
       throw new IOException("connection is closed");
     }
     return connection.getTable(TableName.META_TABLE_NAME);

hbase-client/src/main/java/org/apache/hadoop/hbase/protobuf/ProtobufUtil.java

@@ -38,6 +38,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.NavigableSet;
+import java.util.Objects;
 import java.util.function.Function;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.Cell;
@@ -1594,14 +1595,13 @@ public static ScanMetrics toScanMetrics(final byte[] bytes) {
   }
 
   /**
-   * Unwraps an exception from a protobuf service into the underlying (expected) IOException.
-   * This method will <strong>always</strong> throw an exception.
+   * Unwraps an exception from a protobuf service into the underlying (expected) IOException. This
+   * method will <strong>always</strong> throw an exception.
    * @param se the {@code ServiceException} instance to convert into an {@code IOException}
+   * @throws NullPointerException if {@code se} is {@code null}
    */
   public static void toIOException(ServiceException se) throws IOException {
-    if (se == null) {
-      throw new NullPointerException("Null service exception passed!");
-    }
+    Objects.requireNonNull(se, "Service exception cannot be null");
 
     Throwable cause = se.getCause();
     if (cause != null && cause instanceof IOException) {

hbase-client/src/main/java/org/apache/hadoop/hbase/security/access/AccessControlUtil.java

@@ -21,6 +21,7 @@
 import java.util.Collection;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 
 import org.apache.commons.lang3.StringUtils;
 import org.apache.hadoop.hbase.HConstants;
@@ -56,6 +57,7 @@ private AccessControlUtil() {}
    * @param qualifier optional qualifier
    * @param actions the permissions to be granted
    * @return A {@link AccessControlProtos} GrantRequest
+   * @throws NullPointerException if {@code tableName} is {@code null}
    */
   public static AccessControlProtos.GrantRequest buildGrantRequest(
       String username, TableName tableName, byte[] family, byte[] qualifier,
@@ -67,9 +69,9 @@ public static AccessControlProtos.GrantRequest buildGrantRequest(
     for (AccessControlProtos.Permission.Action a : actions) {
       permissionBuilder.addAction(a);
     }
-    if (tableName == null) {
-      throw new NullPointerException("TableName cannot be null");
-    }
+
+    Objects.requireNonNull(tableName, "TableName cannot be null");
+
     permissionBuilder.setTableName(ProtobufUtil.toProtoTableName(tableName));
 
     if (family != null) {

hbase-client/src/main/java/org/apache/hadoop/hbase/shaded/protobuf/ProtobufUtil.java

@@ -35,6 +35,7 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.NavigableSet;
+import java.util.Objects;
 import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.Callable;
@@ -1965,14 +1966,13 @@ public static MapReduceProtos.ScanMetrics toScanMetrics(ScanMetrics scanMetrics,
   }
 
   /**
-   * Unwraps an exception from a protobuf service into the underlying (expected) IOException.
-   * This method will <strong>always</strong> throw an exception.
+   * Unwraps an exception from a protobuf service into the underlying (expected) IOException. This
+   * method will <strong>always</strong> throw an exception.
    * @param se the {@code ServiceException} instance to convert into an {@code IOException}
+   * @throws NullPointerException if {@code se} is {@code null}
    */
   public static void toIOException(ServiceException se) throws IOException {
-    if (se == null) {
-      throw new NullPointerException("Null service exception passed!");
-    }
+    Objects.requireNonNull(se, "Service exception cannot be null");
 
     Throwable cause = se.getCause();
     if (cause != null && cause instanceof IOException) {

hbase-common/src/main/java/org/apache/hadoop/hbase/io/ByteBufferWriterOutputStream.java

@@ -20,6 +20,7 @@
 import java.io.IOException;
 import java.io.OutputStream;
 import java.nio.ByteBuffer;
+import java.util.Objects;
 
 import org.apache.hadoop.hbase.io.util.StreamUtils;
 import org.apache.hadoop.hbase.util.ByteBufferUtils;
@@ -58,22 +59,21 @@ public ByteBufferWriterOutputStream(OutputStream os, int size) {
   }
 
   /**
-   * Writes len bytes from the specified ByteBuffer starting at offset off to
-   * this OutputStream. If b is null, a NullPointerException is thrown. If off
-   * is negative or larger than the ByteBuffer then an ArrayIndexOutOfBoundsException
-   * is thrown. If len is greater than the length of the ByteBuffer, then an
-   * ArrayIndexOutOfBoundsException is thrown. This method does not change the
-   * position of the ByteBuffer.
-   *
-   * @param b    the ByteBuffer
-   * @param off  the start offset in the data
-   * @param len  the number of bytes to write
-   * @throws IOException
-   *             if an I/O error occurs. In particular, an IOException is thrown
-   *             if the output stream is closed.
+   * Writes len bytes from the specified ByteBuffer starting at offset off to this OutputStream. If
+   * off is negative or larger than the ByteBuffer then an ArrayIndexOutOfBoundsException is thrown.
+   * If len is greater than the length of the ByteBuffer, then an ArrayIndexOutOfBoundsException is
+   * thrown. This method does not change the position of the ByteBuffer.
+   * @param b the ByteBuffer
+   * @param off the start offset in the data
+   * @param len the number of bytes to write
+   * @throws IOException if an I/O error occurs. In particular, an IOException is thrown if the
+   *           output stream is closed.
+   * @throws NullPointerException if {@code b} is {@code null}
    */
   @Override
   public void write(ByteBuffer b, int off, int len) throws IOException {
+    Objects.requireNonNull(b);
+
     // Lazily load in the event that this version of 'write' is not invoked
     if (this.buf == null) {
       this.buf = new byte[this.bufSize];

hbase-common/src/main/java/org/apache/hadoop/hbase/io/crypto/aes/AESDecryptor.java

@@ -83,10 +83,8 @@ public void reset() {
   }
 
   protected void init() {
+    Preconditions.checkState(iv != null, "IV is null");
     try {
-      if (iv == null) {
-        throw new NullPointerException("IV is null");
-      }
       cipher.init(javax.crypto.Cipher.DECRYPT_MODE, key, new IvParameterSpec(iv));
     } catch (InvalidKeyException e) {
       throw new RuntimeException(e);

hbase-common/src/main/java/org/apache/hadoop/hbase/util/AbstractHBaseTool.java

@@ -21,6 +21,7 @@
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.List;
+import java.util.Objects;
 
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.HBaseConfiguration;
@@ -115,10 +116,8 @@ public void setConf(Configuration conf) {
   @Override
   public int run(String[] args) throws IOException {
     cmdLineArgs = args;
-    if (conf == null) {
-      LOG.error("Tool configuration is not initialized");
-      throw new NullPointerException("conf");
-    }
+
+    Objects.requireNonNull(conf, "Tool configuration is not initialized");
 
     CommandLine cmd;
     List<String> argsList = new ArrayList<>(args.length);

hbase-common/src/main/java/org/apache/hadoop/hbase/util/CommonFSUtils.java

@@ -27,6 +27,7 @@
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
+import java.util.Objects;
 import java.util.concurrent.ConcurrentHashMap;
 import org.apache.hadoop.HadoopIllegalArgumentException;
 import org.apache.hadoop.conf.Configuration;
@@ -1018,19 +1019,18 @@ private static class StreamCapabilities {
   }
 
   /**
-   * If our FileSystem version includes the StreamCapabilities class, check if
-   * the given stream has a particular capability.
+   * If our FileSystem version includes the StreamCapabilities class, check if the given stream has
+   * a particular capability.
    * @param stream capabilities are per-stream instance, so check this one specifically. must not be
-   *        null
+   *          null
    * @param capability what to look for, per Hadoop Common's FileSystem docs
    * @return true if there are no StreamCapabilities. false if there are, but this stream doesn't
    *         implement it. return result of asking the stream otherwise.
+   * @throws NullPointerException if {@code stream} is {@code null}
    */
   public static boolean hasCapability(FSDataOutputStream stream, String capability) {
     // be consistent whether or not StreamCapabilities is present
-    if (stream == null) {
-      throw new NullPointerException("stream parameter must not be null.");
-    }
+    Objects.requireNonNull(stream, "stream cannot be null");
     // If o.a.h.fs.StreamCapabilities doesn't exist, assume everyone does everything
     // otherwise old versions of Hadoop will break.
     boolean result = true;

hbase-common/src/main/java/org/apache/hadoop/hbase/util/ObjectPool.java

@@ -20,6 +20,7 @@
 
 import java.lang.ref.Reference;
 import java.lang.ref.ReferenceQueue;
+import java.util.Objects;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.locks.Lock;
@@ -75,7 +76,7 @@ public interface ObjectFactory<K, V> {
    *
    * @param objectFactory the factory to supply new objects on demand
    *
-   * @throws NullPointerException if {@code objectFactory} is null
+   * @throws NullPointerException if {@code objectFactory} is {@code null}
    */
   public ObjectPool(ObjectFactory<K, V> objectFactory) {
     this(objectFactory, DEFAULT_INITIAL_CAPACITY, DEFAULT_CONCURRENCY_LEVEL);
@@ -88,7 +89,7 @@ public ObjectPool(ObjectFactory<K, V> objectFactory) {
    * @param objectFactory the factory to supply new objects on demand
    * @param initialCapacity the initial capacity to keep objects in the pool
    *
-   * @throws NullPointerException if {@code objectFactory} is null
+   * @throws NullPointerException if {@code objectFactory} is {@code null}
    * @throws IllegalArgumentException if {@code initialCapacity} is negative
    */
   public ObjectPool(ObjectFactory<K, V> objectFactory, int initialCapacity) {
@@ -103,7 +104,7 @@ public ObjectPool(ObjectFactory<K, V> objectFactory, int initialCapacity) {
    * @param initialCapacity the initial capacity to keep objects in the pool
    * @param concurrencyLevel the estimated count of concurrently accessing threads
    *
-   * @throws NullPointerException if {@code objectFactory} is null
+   * @throws NullPointerException if {@code objectFactory} is {@code null}
    * @throws IllegalArgumentException if {@code initialCapacity} is negative or
    *    {@code concurrencyLevel} is non-positive
    */
@@ -112,10 +113,7 @@ public ObjectPool(
       int initialCapacity,
       int concurrencyLevel) {
 
-    if (objectFactory == null) {
-      throw new NullPointerException("Given object factory instance is NULL");
-    }
-    this.objectFactory = objectFactory;
+    this.objectFactory = Objects.requireNonNull(objectFactory, "Object factory cannot be null");
 
     this.referenceCache =
         new ConcurrentHashMap<K, Reference<V>>(initialCapacity, 0.75f, concurrencyLevel);
@@ -164,10 +162,10 @@ public void purge() {
   /**
    * Returns a shared object associated with the given {@code key},
    * which is identified by the {@code equals} method.
-   * @throws NullPointerException if {@code key} is null
+   * @throws NullPointerException if {@code key} is {@code null}
    */
   public V get(K key) {
-    Reference<V> ref = referenceCache.get(key);
+    Reference<V> ref = referenceCache.get(Objects.requireNonNull(key));
     if (ref != null) {
       V obj = ref.get();
       if (obj != null) {

hbase-server/src/main/java/org/apache/hadoop/hbase/filter/FilterWrapper.java

@@ -21,6 +21,7 @@
 
 import java.io.IOException;
 import java.util.List;
+import java.util.Objects;
 
 import org.apache.hadoop.hbase.Cell;
 import org.apache.yetus.audience.InterfaceAudience;
@@ -40,12 +41,13 @@
 final public class FilterWrapper extends Filter {
   Filter filter = null;
 
-  public FilterWrapper( Filter filter ) {
-    if (null == filter) {
-      // ensure the filter instance is not null
-      throw new NullPointerException("Cannot create FilterWrapper with null Filter");
-    }
-    this.filter = filter;
+  /**
+   * Constructor.
+   * @param filter filter to wrap
+   * @throws NullPointerException if {@code filter} is {@code null}
+   */
+  public FilterWrapper(Filter filter) {
+    this.filter = Objects.requireNonNull(filter, "Cannot create FilterWrapper with null Filter");
   }
 
   /**

hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/CompoundBloomFilterWriter.java

@@ -21,6 +21,7 @@
 import java.io.DataOutput;
 import java.io.IOException;
 import java.util.ArrayDeque;
+import java.util.Objects;
 import java.util.Queue;
 
 import org.apache.hadoop.hbase.Cell;
@@ -163,8 +164,7 @@ private void enqueueReadyChunk(boolean closing) {
 
   @Override
   public void append(Cell cell) throws IOException {
-    if (cell == null)
-      throw new NullPointerException();
+    Objects.requireNonNull(cell);
 
     enqueueReadyChunk(false);
 

hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileInfo.java

@@ -29,6 +29,7 @@
 import java.util.Comparator;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Set;
 import java.util.SortedMap;
 import java.util.TreeMap;
@@ -122,12 +123,13 @@ public HFileInfo(ReaderContext context, Configuration conf) throws IOException {
    *          with the reserved prefix
    * @return this file info object
    * @throws IOException if the key or value is invalid
+   * @throws NullPointerException if {@code key} or {@code value} is {@code null}
    */
   public HFileInfo append(final byte[] k, final byte[] v,
       final boolean checkPrefix) throws IOException {
-    if (k == null || v == null) {
-      throw new NullPointerException("Key nor value may be null");
-    }
+    Objects.requireNonNull(k, "key cannot be null");
+    Objects.requireNonNull(v, "value cannot be null");
+
     if (checkPrefix && isReservedFileInfoKey(k)) {
       throw new IOException("Keys with a " + HFileInfo.RESERVED_PREFIX
           + " are reserved");