Merge pull request #390 from fyrz/RocksJava-Cleanup

[RocksJava] Cleanup

java/org/rocksdb/AbstractComparator.java

@@ -46,15 +46,18 @@ public abstract class AbstractComparator<T extends AbstractSlice>
   public abstract int compare(final T a, final T b);
 
   /**
-   * Used to reduce the space requirements
-   * for internal data structures like index blocks.
+   * <p>Used to reduce the space requirements
+   * for internal data structures like index blocks.</p>
    *
-   * If start &lt; limit, you may return a new start which is a
-   * shorter string in [start, limit).
+   * <p>If start &lt; limit, you may return a new start which is a
+   * shorter string in [start, limit).</p>
    *
-   * Simple comparator implementations may return null if they
+   * <p>Simple comparator implementations may return null if they
    * wish to use start unchanged. i.e., an implementation of
-   * this method that does nothing is correct.
+   * this method that does nothing is correct.</p>
+   *
+   * @param start String
+   * @param limit of type T
    *
    * @return a shorter start, or null
    */
@@ -63,15 +66,17 @@ public abstract class AbstractComparator<T extends AbstractSlice>
   }
 
   /**
-   * Used to reduce the space requirements
-   * for internal data structures like index blocks.
+   * <p>Used to reduce the space requirements
+   * for internal data structures like index blocks.</p>
    *
-   * You may return a new short key (key1) where
-   * key1 &ge; key.
+   * <p>You may return a new short key (key1) where
+   * key1 &ge; key.</p>
    *
-   * Simple comparator implementations may return null if they
+   * <p>Simple comparator implementations may return null if they
    * wish to leave the key unchanged. i.e., an implementation of
-   * this method that does nothing is correct.
+   * this method that does nothing is correct.</p>
+   *
+   * @param key String
    *
    * @return a shorter key, or null
    */

java/org/rocksdb/BackupableDB.java

@@ -23,6 +23,9 @@ public class BackupableDB extends RocksDB {
    * @param db_path Path to store data to. The path for storing the backup should be
    *     specified in the {@link org.rocksdb.BackupableDBOptions}.
    * @return BackupableDB reference to the opened database.
+   *
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public static BackupableDB open(
       Options opt, BackupableDBOptions bopt, String db_path)
@@ -45,7 +48,9 @@ public class BackupableDB extends RocksDB {
    *
    * @param flushBeforeBackup if true, then all data will be flushed
    *     before creating backup.
-   * @throws org.rocksdb.RocksDBException
+   *
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public void createNewBackup(boolean flushBeforeBackup)
       throws RocksDBException {
@@ -56,7 +61,9 @@ public class BackupableDB extends RocksDB {
    * Deletes old backups, keeping latest numBackupsToKeep alive.
    *
    * @param numBackupsToKeep Number of latest backups to keep.
-   * @throws org.rocksdb.RocksDBException
+   *
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public void purgeOldBackups(int numBackupsToKeep)
       throws RocksDBException {
@@ -67,7 +74,9 @@ public class BackupableDB extends RocksDB {
    * Deletes a specific backup.
    *
    * @param backupId of backup to delete.
-   * @throws org.rocksdb.RocksDBException
+   *
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public void deleteBackup(int backupId) throws RocksDBException {
     deleteBackup0(nativeHandle_, backupId);
@@ -104,7 +113,7 @@ public class BackupableDB extends RocksDB {
     super();
   }
 
-  @Override protected void finalize() {
+  @Override protected void finalize() throws Throwable {
     close();
     super.finalize();
   }

java/org/rocksdb/ColumnFamilyOptionsInterface.java

@@ -152,7 +152,8 @@ public interface ColumnFamilyOptionsInterface {
    * Default: 4MB
    * @param writeBufferSize the size of write buffer.
    * @return the instance of the current Object.
-   * @throws org.rocksdb.RocksDBException
+   * @throws org.rocksdb.RocksDBException thrown on 32-Bit platforms while
+   *    overflowing the underlying platform specific value.
    */
   Object setWriteBufferSize(long writeBufferSize)
       throws RocksDBException;
@@ -223,6 +224,7 @@ public interface ColumnFamilyOptionsInterface {
    * extract the prefix given a key.
    *
    * @param n use the first n bytes of a key as its prefix.
+   * @return the reference to the current option.
    */
   Object useFixedLengthPrefixExtractor(int n);
 
@@ -415,6 +417,8 @@ public interface ColumnFamilyOptionsInterface {
    * and total file size for level-3 will be 2GB.
    * by default 'maxBytesForLevelBase' is 10MB.
    *
+   * @param maxBytesForLevelBase maximum bytes for level base.
+   *
    * @return the reference to the current option.
    * @see #setMaxBytesForLevelMultiplier(int)
    */
@@ -614,7 +618,8 @@ public interface ColumnFamilyOptionsInterface {
    *
    * @param arenaBlockSize the size of an arena block
    * @return the reference to the current option.
-   * @throws org.rocksdb.RocksDBException
+   * @throws org.rocksdb.RocksDBException thrown on 32-Bit platforms while
+   *    overflowing the underlying platform specific value.
    */
   Object setArenaBlockSize(long arenaBlockSize)
       throws RocksDBException;
@@ -762,7 +767,8 @@ public interface ColumnFamilyOptionsInterface {
    *
    * @param config the mem-table config.
    * @return the instance of the current Object.
-   * @throws org.rocksdb.RocksDBException
+   * @throws org.rocksdb.RocksDBException thrown on 32-Bit platforms while
+   *    overflowing the underlying platform specific value.
    */
   Object setMemTableConfig(MemTableConfig config)
       throws RocksDBException;
@@ -826,7 +832,8 @@ public interface ColumnFamilyOptionsInterface {
    * @param inplaceUpdateNumLocks the number of locks used for
    *     inplace updates.
    * @return the reference to the current option.
-   * @throws org.rocksdb.RocksDBException
+   * @throws org.rocksdb.RocksDBException thrown on 32-Bit platforms while
+   *    overflowing the underlying platform specific value.
    */
   Object setInplaceUpdateNumLocks(long inplaceUpdateNumLocks)
       throws RocksDBException;
@@ -920,7 +927,8 @@ public interface ColumnFamilyOptionsInterface {
    *
    * @param maxSuccessiveMerges the maximum number of successive merges.
    * @return the reference to the current option.
-   * @throws org.rocksdb.RocksDBException
+   * @throws org.rocksdb.RocksDBException thrown on 32-Bit platforms while
+   *    overflowing the underlying platform specific value.
    */
   Object setMaxSuccessiveMerges(long maxSuccessiveMerges)
       throws RocksDBException;

java/org/rocksdb/DBOptionsInterface.java

@@ -123,7 +123,7 @@ public interface DBOptionsInterface {
    * Default: 5000
    *
    * @param maxOpenFiles the maximum number of open files.
-   * @return the reference to the current DBOptions.
+   * @return the instance of the current Object.
    */
   Object setMaxOpenFiles(int maxOpenFiles);
 
@@ -147,6 +147,9 @@ public interface DBOptionsInterface {
    * <p>If set to 0 (default), we will dynamically choose the WAL size limit to
    * be [sum of all write_buffer_size * max_write_buffer_number] * 2</p>
    * <p>Default: 0</p>
+   *
+   * @param maxTotalWalSize max total wal size.
+   * @return the instance of the current Object.
    */
   Object setMaxTotalWalSize(long maxTotalWalSize);
 
@@ -197,7 +200,7 @@ public interface DBOptionsInterface {
    *
    * @param disableDataSync a boolean flag to specify whether to
    *     disable data sync.
-   * @return the reference to the current DBOptions.
+   * @return the instance of the current Object.
    */
   Object setDisableDataSync(boolean disableDataSync);
 
@@ -370,7 +373,8 @@ public interface DBOptionsInterface {
    *
    * @param maxLogFileSize the maximum size of a info log file.
    * @return the instance of the current Object.
-   * @throws org.rocksdb.RocksDBException
+   * @throws org.rocksdb.RocksDBException thrown on 32-Bit platforms while
+   *    overflowing the underlying platform specific value.
    */
   Object setMaxLogFileSize(long maxLogFileSize)
       throws RocksDBException;
@@ -392,7 +396,8 @@ public interface DBOptionsInterface {
    *
    * @param logFileTimeToRoll the time interval in seconds.
    * @return the instance of the current Object.
-   * @throws org.rocksdb.RocksDBException
+   * @throws org.rocksdb.RocksDBException thrown on 32-Bit platforms while
+   *    overflowing the underlying platform specific value.
    */
   Object setLogFileTimeToRoll(long logFileTimeToRoll)
       throws RocksDBException;
@@ -413,7 +418,8 @@ public interface DBOptionsInterface {
    *
    * @param keepLogFileNum the maximum number of info log files to be kept.
    * @return the instance of the current Object.
-   * @throws org.rocksdb.RocksDBException
+   * @throws org.rocksdb.RocksDBException thrown on 32-Bit platforms while
+   *    overflowing the underlying platform specific value.
    */
   Object setKeepLogFileNum(long keepLogFileNum)
       throws RocksDBException;
@@ -584,7 +590,8 @@ public interface DBOptionsInterface {
    *
    * @param size the size in byte
    * @return the instance of the current Object.
-   * @throws org.rocksdb.RocksDBException
+   * @throws org.rocksdb.RocksDBException thrown on 32-Bit platforms while
+   *    overflowing the underlying platform specific value.
    */
   Object setManifestPreallocationSize(long size)
       throws RocksDBException;

java/org/rocksdb/HashSkipListMemTableConfig.java

@@ -50,6 +50,8 @@ public class HashSkipListMemTableConfig extends MemTableConfig {
   /**
    * Set the height of the skip list.  Default = 4.
    *
+   * @param height height to set.
+   *
    * @return the reference to the current HashSkipListMemTableConfig.
    */
   public HashSkipListMemTableConfig setHeight(int height) {

java/org/rocksdb/MemTableConfig.java

@@ -22,6 +22,11 @@ public abstract class MemTableConfig {
    * that associated with the Java MemTableConfig.
    *
    * @see Options#setMemTableConfig(MemTableConfig)
+   *
+   * @return native handle address to native memory table instance.
+   *
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   abstract protected long newMemTableFactoryHandle()
       throws RocksDBException;

java/org/rocksdb/MergeOperator.java

@@ -5,8 +5,6 @@
 
 package org.rocksdb;
 
-import java.util.*;
-
 /**
  * MergeOperator holds an operator to be applied when compacting
  * two merge operands held under the same key in order to obtain a single

java/org/rocksdb/NativeLibraryLoader.java

@@ -9,12 +9,12 @@ import org.rocksdb.util.Environment;
  */
 public class NativeLibraryLoader {
   private static String sharedLibraryName = Environment.getJniLibraryName("rocksdb");
-  private static String tempFilePrefix = "librocksdbjni";
   private static String tempFileSuffix = "." + Environment.getJniLibraryExtension();
 
   public static void loadLibraryFromJar(String tmpDir)
       throws IOException {
     File temp;
+    String tempFilePrefix = "librocksdbjni";
     if(tmpDir == null || tmpDir.equals(""))
       temp = File.createTempFile(tempFilePrefix, tempFileSuffix);
     else
@@ -43,9 +43,7 @@ public class NativeLibraryLoader {
     } finally {
       if(os != null)
         os.close();
-
-      if(is != null)
-        is.close();
+      is.close();
     }
 
     System.load(temp.getAbsolutePath());

java/org/rocksdb/Options.java

@@ -61,6 +61,9 @@ public class Options extends RocksObject
    * Use the specified object to interact with the environment,
    * e.g. to read/write files, schedule background work, etc.
    * Default: {@link RocksEnv#getDefault()}
+   *
+   * @param env {@link RocksEnv} instance.
+   * @return the instance of the current Options.
    */
   public Options setEnv(RocksEnv env) {
     assert(isInitialized());
@@ -69,6 +72,11 @@ public class Options extends RocksObject
     return this;
   }
 
+  /**
+   * Returns the set RocksEnv instance.
+   *
+   * @return {@link RocksEnv} instance set in the Options.
+   */
   public RocksEnv getEnv() {
     return env_;
   }

java/org/rocksdb/PlainTableConfig.java

@@ -131,7 +131,7 @@ public class PlainTableConfig extends TableFormatConfig {
    *
    * <p>See linux doc Documentation/vm/hugetlbpage.txt</p>
    *
-   * @param hugePageTlbSize
+   * @param hugePageTlbSize huge page tlb size
    * @return the reference to the current config.
    */
   public PlainTableConfig setHugePageTlbSize(int hugePageTlbSize) {

java/org/rocksdb/RateLimiterConfig.java

@@ -16,6 +16,8 @@ public abstract class RateLimiterConfig {
    * with a Java RateLimiterConfig.
    *
    * @see org.rocksdb.DBOptions#setRateLimiter(long, long)
+   *
+   * @return native handle address to rate limiter instance.
    */
   abstract protected long newRateLimiterHandle();
 }

java/org/rocksdb/RestoreBackupableDB.java

@@ -40,8 +40,10 @@ public class RestoreBackupableDB extends RocksObject {
    * @param backupId id pointing to backup
    * @param dbDir database directory to restore to
    * @param walDir directory where wal files are located
-   * @param restoreOptions {@link org.rocksdb.RestoreOptions} instance
-   * @throws RocksDBException
+   * @param restoreOptions {@link org.rocksdb.RestoreOptions} instance.
+   *
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public void restoreDBFromBackup(long backupId, String dbDir, String walDir,
       RestoreOptions restoreOptions) throws RocksDBException {
@@ -55,7 +57,9 @@ public class RestoreBackupableDB extends RocksObject {
    * @param dbDir database directory to restore to
    * @param walDir directory where wal files are located
    * @param restoreOptions {@link org.rocksdb.RestoreOptions} instance
-   * @throws RocksDBException
+   *
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public void restoreDBFromLatestBackup(String dbDir, String walDir,
       RestoreOptions restoreOptions) throws RocksDBException {
@@ -67,7 +71,9 @@ public class RestoreBackupableDB extends RocksObject {
    * Deletes old backups, keeping latest numBackupsToKeep alive.
    *
    * @param numBackupsToKeep of latest backups to keep
-   * @throws org.rocksdb.RocksDBException
+   *
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public void purgeOldBackups(int numBackupsToKeep) throws RocksDBException {
     purgeOldBackups0(nativeHandle_, numBackupsToKeep);
@@ -77,7 +83,9 @@ public class RestoreBackupableDB extends RocksObject {
    * Deletes a specific backup.
    *
    * @param backupId of backup to delete.
-   * @throws org.rocksdb.RocksDBException
+   *
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public void deleteBackup(int backupId) throws RocksDBException {
     deleteBackup0(nativeHandle_, backupId);

java/org/rocksdb/RocksDB.java

@@ -95,7 +95,8 @@ public class RocksDB extends RocksObject {
    * @return a {@link RocksDB} instance on success, null if the specified
    *     {@link RocksDB} can not be opened.
    *
-   * @throws org.rocksdb.RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    * @see Options#setCreateIfMissing(boolean)
    */
   public static RocksDB open(String path) throws RocksDBException {
@@ -130,7 +131,8 @@ public class RocksDB extends RocksObject {
    * @return a {@link RocksDB} instance on success, null if the specified
    *     {@link RocksDB} can not be opened.
    *
-   * @throws org.rocksdb.RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    * @see DBOptions#setCreateIfMissing(boolean)
    */
   public static RocksDB open(String path,
@@ -161,7 +163,9 @@ public class RocksDB extends RocksObject {
    * @return a {@link RocksDB} instance on success, null if the specified
    *     {@link RocksDB} can not be opened.
    *
-   * @throws org.rocksdb.RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
+   *
    * @see Options#setCreateIfMissing(boolean)
    */
   public static RocksDB open(Options options, String path)
@@ -206,7 +210,9 @@ public class RocksDB extends RocksObject {
    * @return a {@link RocksDB} instance on success, null if the specified
    *     {@link RocksDB} can not be opened.
    *
-   * @throws org.rocksdb.RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
+   *
    * @see DBOptions#setCreateIfMissing(boolean)
    */
   public static RocksDB open(DBOptions options, String path,
@@ -231,7 +237,9 @@ public class RocksDB extends RocksObject {
    * @param path the path to the RocksDB.
    * @return a {@link RocksDB} instance on success, null if the specified
    *     {@link RocksDB} can not be opened.
-   * @throws RocksDBException
+   *
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public static RocksDB openReadOnly(String path)
       throws RocksDBException {
@@ -252,7 +260,9 @@ public class RocksDB extends RocksObject {
    *     on open.
    * @return a {@link RocksDB} instance on success, null if the specified
    *     {@link RocksDB} can not be opened.
-   * @throws RocksDBException
+   *
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public static RocksDB openReadOnly(String path,
       List<ColumnFamilyDescriptor> columnFamilyDescriptors,
@@ -277,7 +287,9 @@ public class RocksDB extends RocksObject {
    * @param path the path to the RocksDB.
    * @return a {@link RocksDB} instance on success, null if the specified
    *     {@link RocksDB} can not be opened.
-   * @throws RocksDBException
+   *
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public static RocksDB openReadOnly(Options options, String path)
       throws RocksDBException {
@@ -309,7 +321,9 @@ public class RocksDB extends RocksObject {
    *     on open.
    * @return a {@link RocksDB} instance on success, null if the specified
    *     {@link RocksDB} can not be opened.
-   * @throws RocksDBException
+   *
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public static RocksDB openReadOnly(DBOptions options, String path,
       List<ColumnFamilyDescriptor> columnFamilyDescriptors,
@@ -336,7 +350,8 @@ public class RocksDB extends RocksObject {
    * @param path Absolute path to rocksdb database
    * @return List&lt;byte[]&gt; List containing the column family names
    *
-   * @throws RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public static List<byte[]> listColumnFamilies(Options options, String path)
       throws RocksDBException {
@@ -366,7 +381,8 @@ public class RocksDB extends RocksObject {
    * @param key the specified key to be inserted.
    * @param value the value associated with the specified key.
    *
-   * @see RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public void put(byte[] key, byte[] value) throws RocksDBException {
     put(nativeHandle_, key, key.length, value, value.length);
@@ -383,7 +399,8 @@ public class RocksDB extends RocksObject {
    *
    * throws IllegalArgumentException if column family is not present
    *
-   * @see RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public void put(ColumnFamilyHandle columnFamilyHandle, byte[] key,
       byte[] value) throws RocksDBException {
@@ -394,10 +411,12 @@ public class RocksDB extends RocksObject {
   /**
    * Set the database entry for "key" to "value".
    *
+   * @param writeOpts {@link org.rocksdb.WriteOptions} instance.
    * @param key the specified key to be inserted.
    * @param value the value associated with the specified key.
    *
-   * @see RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public void put(WriteOptions writeOpts, byte[] key, byte[] value)
       throws RocksDBException {
@@ -411,12 +430,14 @@ public class RocksDB extends RocksObject {
    *
    * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
    *     instance
+   * @param writeOpts {@link org.rocksdb.WriteOptions} instance.
    * @param key the specified key to be inserted.
    * @param value the value associated with the specified key.
    *
    * throws IllegalArgumentException if column family is not present
    *
-   * @see RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    * @see IllegalArgumentException
    */
   public void put(ColumnFamilyHandle columnFamilyHandle, WriteOptions writeOpts,
@@ -506,7 +527,8 @@ public class RocksDB extends RocksObject {
    * @param writeOpts WriteOptions instance
    * @param updates WriteBatch instance
    *
-   * @see RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public void write(WriteOptions writeOpts, WriteBatch updates)
       throws RocksDBException {
@@ -517,8 +539,11 @@ public class RocksDB extends RocksObject {
    * Add merge operand for key/value pair.
    *
    * @param key the specified key to be merged.
-   * @param value the value to be nerged with the current value for
+   * @param value the value to be merged with the current value for
    * the specified key.
+   *
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public void merge(byte[] key, byte[] value) throws RocksDBException {
     merge(nativeHandle_, key, key.length, value, value.length);
@@ -529,8 +554,11 @@ public class RocksDB extends RocksObject {
    *
    * @param columnFamilyHandle {@link ColumnFamilyHandle} instance
    * @param key the specified key to be merged.
-   * @param value the value to be nerged with the current value for
+   * @param value the value to be merged with the current value for
    * the specified key.
+   *
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public void merge(ColumnFamilyHandle columnFamilyHandle, byte[] key,
       byte[] value) throws RocksDBException {
@@ -545,6 +573,9 @@ public class RocksDB extends RocksObject {
    * @param key the specified key to be merged.
    * @param value the value to be merged with the current value for
    * the specified key.
+   *
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public void merge(WriteOptions writeOpts, byte[] key, byte[] value)
       throws RocksDBException {
@@ -560,6 +591,9 @@ public class RocksDB extends RocksObject {
    * @param key the specified key to be merged.
    * @param value the value to be merged with the current value for
    * the specified key.
+   *
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public void merge(ColumnFamilyHandle columnFamilyHandle,
       WriteOptions writeOpts, byte[] key, byte[] value)
@@ -580,7 +614,8 @@ public class RocksDB extends RocksObject {
    *     be returned.  RocksDB.NOT_FOUND will be returned if the value not
    *     found.
    *
-   * @see RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public int get(byte[] key, byte[] value) throws RocksDBException {
     return get(nativeHandle_, key, key.length, value, value.length);
@@ -600,7 +635,8 @@ public class RocksDB extends RocksObject {
    *     be returned.  RocksDB.NOT_FOUND will be returned if the value not
    *     found.
    *
-   * @throws RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public int get(ColumnFamilyHandle columnFamilyHandle, byte[] key, byte[] value)
       throws RocksDBException, IllegalArgumentException {
@@ -611,6 +647,7 @@ public class RocksDB extends RocksObject {
   /**
    * Get the value associated with the specified key.
    *
+   * @param opt {@link org.rocksdb.ReadOptions} instance.
    * @param key the key to retrieve the value.
    * @param value the out-value to receive the retrieved value.
    * @return The size of the actual value that matches the specified
@@ -620,7 +657,8 @@ public class RocksDB extends RocksObject {
    *     be returned.  RocksDB.NOT_FOUND will be returned if the value not
    *     found.
    *
-   * @throws RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public int get(ReadOptions opt, byte[] key, byte[] value)
       throws RocksDBException {
@@ -632,6 +670,7 @@ public class RocksDB extends RocksObject {
    *
    * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
    *     instance
+   * @param opt {@link org.rocksdb.ReadOptions} instance.
    * @param key the key to retrieve the value.
    * @param value the out-value to receive the retrieved value.
    * @return The size of the actual value that matches the specified
@@ -641,7 +680,8 @@ public class RocksDB extends RocksObject {
    *     be returned.  RocksDB.NOT_FOUND will be returned if the value not
    *     found.
    *
-   * @throws RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public int get(ColumnFamilyHandle columnFamilyHandle, ReadOptions opt, byte[] key,
       byte[] value) throws RocksDBException {
@@ -658,7 +698,8 @@ public class RocksDB extends RocksObject {
    * @return a byte array storing the value associated with the input key if
    *     any.  null if it does not find the specified key.
    *
-   * @throws RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public byte[] get(byte[] key) throws RocksDBException {
     return get(nativeHandle_, key, key.length);
@@ -675,7 +716,8 @@ public class RocksDB extends RocksObject {
    * @return a byte array storing the value associated with the input key if
    *     any.  null if it does not find the specified key.
    *
-   * @throws RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public byte[] get(ColumnFamilyHandle columnFamilyHandle, byte[] key)
       throws RocksDBException {
@@ -692,7 +734,8 @@ public class RocksDB extends RocksObject {
    * @return a byte array storing the value associated with the input key if
    *     any.  null if it does not find the specified key.
    *
-   * @throws RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public byte[] get(ReadOptions opt, byte[] key) throws RocksDBException {
     return get(nativeHandle_, opt.nativeHandle_, key, key.length);
@@ -710,7 +753,8 @@ public class RocksDB extends RocksObject {
    * @return a byte array storing the value associated with the input key if
    *     any.  null if it does not find the specified key.
    *
-   * @throws RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public byte[] get(ColumnFamilyHandle columnFamilyHandle, ReadOptions opt,
       byte[] key) throws RocksDBException {
@@ -725,7 +769,8 @@ public class RocksDB extends RocksObject {
    * @return Map where key of map is the key passed by user and value for map
    * entry is the corresponding value in DB.
    *
-   * @throws RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public Map<byte[], byte[]> multiGet(List<byte[]> keys)
       throws RocksDBException {
@@ -734,7 +779,7 @@ public class RocksDB extends RocksObject {
     List<byte[]> values = multiGet(
         nativeHandle_, keys, keys.size());
 
-    Map<byte[], byte[]> keyValueMap = new HashMap<byte[], byte[]>();
+    Map<byte[], byte[]> keyValueMap = new HashMap<>();
     for(int i = 0; i < values.size(); i++) {
       if(values.get(i) == null) {
         continue;
@@ -759,8 +804,10 @@ public class RocksDB extends RocksObject {
    * @return Map where key of map is the key passed by user and value for map
    * entry is the corresponding value in DB.
    *
-   * @throws RocksDBException
-   * @throws IllegalArgumentException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
+   * @throws IllegalArgumentException thrown if the size of passed keys is not
+   *    equal to the amount of passed column family handles.
    */
   public Map<byte[], byte[]> multiGet(List<ColumnFamilyHandle> columnFamilyHandleList,
       List<byte[]> keys) throws RocksDBException, IllegalArgumentException {
@@ -774,7 +821,7 @@ public class RocksDB extends RocksObject {
     List<byte[]> values = multiGet(nativeHandle_, keys, keys.size(),
         columnFamilyHandleList);
 
-    Map<byte[], byte[]> keyValueMap = new HashMap<byte[], byte[]>();
+    Map<byte[], byte[]> keyValueMap = new HashMap<>();
     for(int i = 0; i < values.size(); i++) {
       if (values.get(i) == null) {
         continue;
@@ -792,7 +839,8 @@ public class RocksDB extends RocksObject {
    * @return Map where key of map is the key passed by user and value for map
    * entry is the corresponding value in DB.
    *
-   * @throws RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public Map<byte[], byte[]> multiGet(ReadOptions opt, List<byte[]> keys)
       throws RocksDBException {
@@ -801,7 +849,7 @@ public class RocksDB extends RocksObject {
     List<byte[]> values = multiGet(
         nativeHandle_, opt.nativeHandle_, keys, keys.size());
 
-    Map<byte[], byte[]> keyValueMap = new HashMap<byte[], byte[]>();
+    Map<byte[], byte[]> keyValueMap = new HashMap<>();
     for(int i = 0; i < values.size(); i++) {
       if(values.get(i) == null) {
         continue;
@@ -827,8 +875,10 @@ public class RocksDB extends RocksObject {
    * @return Map where key of map is the key passed by user and value for map
    * entry is the corresponding value in DB.
    *
-   * @throws RocksDBException
-   * @throws java.lang.IllegalArgumentException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
+   * @throws IllegalArgumentException thrown if the size of passed keys is not
+   *    equal to the amount of passed column family handles.
    */
   public Map<byte[], byte[]> multiGet(ReadOptions opt,
       List<ColumnFamilyHandle> columnFamilyHandleList, List<byte[]> keys)
@@ -844,7 +894,7 @@ public class RocksDB extends RocksObject {
     List<byte[]> values = multiGet(nativeHandle_, opt.nativeHandle_,
         keys, keys.size(), columnFamilyHandleList);
 
-    Map<byte[], byte[]> keyValueMap = new HashMap<byte[], byte[]>();
+    Map<byte[], byte[]> keyValueMap = new HashMap<>();
     for(int i = 0; i < values.size(); i++) {
       if(values.get(i) == null) {
         continue;
@@ -862,7 +912,8 @@ public class RocksDB extends RocksObject {
    *
    * @param key Key to delete within database
    *
-   * @throws RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public void remove(byte[] key) throws RocksDBException {
     remove(nativeHandle_, key, key.length);
@@ -877,7 +928,8 @@ public class RocksDB extends RocksObject {
    *     instance
    * @param key Key to delete within database
    *
-   * @throws RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public void remove(ColumnFamilyHandle columnFamilyHandle, byte[] key)
       throws RocksDBException {
@@ -892,7 +944,8 @@ public class RocksDB extends RocksObject {
    * @param writeOpt WriteOptions to be used with delete operation
    * @param key Key to delete within database
    *
-   * @throws RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public void remove(WriteOptions writeOpt, byte[] key)
       throws RocksDBException {
@@ -909,7 +962,8 @@ public class RocksDB extends RocksObject {
    * @param writeOpt WriteOptions to be used with delete operation
    * @param key Key to delete within database
    *
-   * @throws RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public void remove(ColumnFamilyHandle columnFamilyHandle, WriteOptions writeOpt,
       byte[] key) throws RocksDBException {
@@ -940,7 +994,8 @@ public class RocksDB extends RocksObject {
    * @param property to be fetched. See above for examples
    * @return property value
    *
-   * @throws RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public String getProperty(ColumnFamilyHandle columnFamilyHandle, String property)
       throws RocksDBException {
@@ -967,7 +1022,8 @@ public class RocksDB extends RocksObject {
    * @param property to be fetched. See above for examples
    * @return property value
    *
-   * @throws RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public String getProperty(String property) throws RocksDBException {
     return getProperty0(nativeHandle_, property, property.length());
@@ -997,7 +1053,7 @@ public class RocksDB extends RocksObject {
    * <p>nullptr will be returned if the DB fails to take a snapshot or does
    * not support snapshot.</p>
    *
-   * @return Snapshot
+   * @return Snapshot {@link Snapshot} instance
    */
   public Snapshot getSnapshot() {
     long snapshotHandle = getSnapshot(nativeHandle_);
@@ -1046,12 +1102,13 @@ public class RocksDB extends RocksObject {
    * @return {@link java.util.List} containing {@link org.rocksdb.RocksIterator}
    *     instances
    *
-   * @throws RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public List<RocksIterator> newIterators(
       List<ColumnFamilyHandle> columnFamilyHandleList) throws RocksDBException {
     List<RocksIterator> iterators =
-        new ArrayList<RocksIterator>(columnFamilyHandleList.size());
+        new ArrayList<>(columnFamilyHandleList.size());
 
     long[] iteratorRefs = iterators(nativeHandle_, columnFamilyHandleList);
     for (int i=0; i<columnFamilyHandleList.size(); i++){
@@ -1066,8 +1123,10 @@ public class RocksDB extends RocksObject {
    * The ColumnFamilyHandle is automatically disposed with DB disposal.
    *
    * @param columnFamilyDescriptor column family to be created.
-   * @return {@link org.rocksdb.ColumnFamilyHandle} instance
-   * @see RocksDBException
+   * @return {@link org.rocksdb.ColumnFamilyHandle} instance.
+   *
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public ColumnFamilyHandle createColumnFamily(
       ColumnFamilyDescriptor columnFamilyDescriptor)
@@ -1084,7 +1143,8 @@ public class RocksDB extends RocksObject {
    * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
    *     instance
    *
-   * @throws RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public void dropColumnFamily(ColumnFamilyHandle columnFamilyHandle)
       throws RocksDBException, IllegalArgumentException {

java/org/rocksdb/RocksDBException.java

@@ -5,8 +5,6 @@
 
 package org.rocksdb;
 
-import java.util.*;
-
 /**
  * A RocksDBException encapsulates the error of an operation.  This exception
  * type is used to describe an internal error from the c++ rocksdb library.

java/org/rocksdb/RocksEnv.java

@@ -29,6 +29,8 @@ public class RocksEnv extends RocksObject {
    * belongs to rocksdb c++.  As a result, the returned RocksEnv will not
    * have the ownership of its c++ resource, and calling its dispose()
    * will be no-op.</p>
+   *
+   * @return the default {@link org.rocksdb.RocksEnv} instance.
    */
   public static RocksEnv getDefault() {
     return default_env_;
@@ -38,6 +40,10 @@ public class RocksEnv extends RocksObject {
    * <p>Sets the number of background worker threads of the flush pool
    * for this environment.</p>
    * <p>Default number: 1</p>
+   *
+   * @param num the number of threads
+   *
+   * @return current {@link org.rocksdb.RocksEnv} instance.
    */
   public RocksEnv setBackgroundThreads(int num) {
     return setBackgroundThreads(num, FLUSH_POOL);
@@ -52,6 +58,7 @@ public class RocksEnv extends RocksObject {
    *     FLUSH_POOL or COMPACTION_POOL.
    *
    * <p>Default number: 1</p>
+   * @return current {@link org.rocksdb.RocksEnv} instance.
    */
   public RocksEnv setBackgroundThreads(int num, int poolID) {
     setBackgroundThreads(nativeHandle_, num, poolID);
@@ -66,6 +73,8 @@ public class RocksEnv extends RocksObject {
    *
    * @param poolID the id to specified a thread pool.  Should be either
    *     FLUSH_POOL or COMPACTION_POOL.
+   *
+   * @return the thread pool queue length.
    */
   public int getThreadPoolQueueLen(int poolID) {
     return getThreadPoolQueueLen(nativeHandle_, poolID);

java/org/rocksdb/RocksIterator.java

@@ -112,6 +112,9 @@ public class RocksIterator extends RocksObject {
    * <p>Position at the first key in the source that at or past target
    * The iterator is valid after this call iff the source contains
    * an entry that comes at or past target.</p>
+   *
+   * @param target byte array describing a key or a
+   *     key prefix to seek for.
    */
   public void seek(byte[] target) {
     assert(isInitialized());
@@ -123,7 +126,8 @@ public class RocksIterator extends RocksObject {
    * If non-blocking IO is requested and this operation cannot be
    * satisfied without doing some IO, then this returns Status::Incomplete().
    *
-   * @throws org.rocksdb.RocksDBException
+   * @throws RocksDBException thrown if error happens in underlying
+   *    native library.
    */
   public void status() throws RocksDBException {
     assert(isInitialized());

java/org/rocksdb/RocksObject.java

@@ -37,7 +37,7 @@ public abstract class RocksObject {
    * small in that they seems to only hold a long variable. As a result,
    * they might have low priority in the GC process.  To prevent this,
    * it is suggested to call {@code dispose()} manually.
-   * <p>
+   * </p>
    * <p>
    * Note that once an instance of {@code RocksObject} has been disposed,
    * calling its function will lead undefined behavior.
@@ -107,8 +107,9 @@ public abstract class RocksObject {
    * Simply calls {@code dispose()} and release its c++ resource if it has not
    * yet released.
    */
-  @Override protected void finalize() {
+  @Override protected void finalize() throws Throwable {
     dispose();
+    super.finalize();
   }
 
   /**

java/org/rocksdb/Slice.java

@@ -6,26 +6,26 @@
 package org.rocksdb;
 
 /**
- * Base class for slices which will receive
- * byte[] based access to the underlying data.
+ * <p>Base class for slices which will receive
+ * byte[] based access to the underlying data.</p>
  *
- * byte[] backed slices typically perform better with
+ * <p>byte[] backed slices typically perform better with
  * small keys and values. When using larger keys and
- * values consider using @see org.rocksdb.DirectSlice
+ * values consider using {@link org.rocksdb.DirectSlice}</p>
  */
 public class Slice extends AbstractSlice<byte[]> {
   /**
-   * Called from JNI to construct a new Java Slice
+   * <p>Called from JNI to construct a new Java Slice
    * without an underlying C++ object set
-   * at creation time.
+   * at creation time.</p>
    *
-   * Note: You should be aware that
+   * <p>Note: You should be aware that
    * {@see org.rocksdb.RocksObject#disOwnNativeHandle()} is intentionally
    * called from the default Slice constructor, and that it is marked as
    * private. This is so that developers cannot construct their own default
    * Slice objects (at present). As developers cannot construct their own
    * Slice objects through this, they are not creating underlying C++ Slice
-   * objects, and so there is nothing to free (dispose) from Java.
+   * objects, and so there is nothing to free (dispose) from Java.</p>
    */
   private Slice() {
     super();
@@ -33,9 +33,10 @@ public class Slice extends AbstractSlice<byte[]> {
   }
 
   /**
-   * Constructs a slice
-   * where the data is taken from
-   * a String.
+   * <p>Constructs a slice where the data is taken from
+   * a String.</p>
+   *
+   * @param str String value.
    */
   public Slice(final String str) {
     super();
@@ -43,9 +44,11 @@ public class Slice extends AbstractSlice<byte[]> {
   }
 
   /**
-   * Constructs a slice
-   * where the data is a copy of
-   * the byte array from a specific offset.
+   * <p>Constructs a slice where the data is a copy of
+   * the byte array from a specific offset.</p>
+   *
+   * @param data byte array.
+   * @param offset offset within the byte array.
    */
   public Slice(final byte[] data, final int offset) {
     super();
@@ -53,9 +56,10 @@ public class Slice extends AbstractSlice<byte[]> {
   }
 
   /**
-   * Constructs a slice
-   * where the data is a copy of
-   * the byte array.
+   * <p>Constructs a slice where the data is a copy of
+   * the byte array.</p>
+   *
+   * @param data byte array.
    */
   public Slice(final byte[] data) {
     super();
@@ -63,8 +67,8 @@ public class Slice extends AbstractSlice<byte[]> {
   }
 
   /**
-   * Deletes underlying C++ slice pointer
-   * and any buffered data.
+   * <p>Deletes underlying C++ slice pointer
+   * and any buffered data.</p>
    *
    * <p>
    * Note that this function should be called only after all

java/org/rocksdb/Statistics.java

@@ -24,9 +24,8 @@ public class Statistics {
 
   public HistogramData geHistogramData(HistogramType histogramType) {
     assert(isInitialized());
-    HistogramData hist = geHistogramData0(
+    return geHistogramData0(
         histogramType.getValue(), statsHandle_);
-    return hist;
   }
 
   private boolean isInitialized() {

java/org/rocksdb/StatisticsCollector.java

@@ -6,11 +6,9 @@
 package org.rocksdb;
 
 import java.util.List;
-import java.util.concurrent.ArrayBlockingQueue;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.TimeUnit;
-import java.util.concurrent.atomic.AtomicBoolean;
 
 /**
  * <p>Helper class to collect DB statistics periodically at a period specified in
@@ -51,6 +49,7 @@ public class StatisticsCollector {
    *
    * @param shutdownTimeout Time in milli-seconds to wait for shutdown before
    *        killing the collection process.
+   * @throws java.lang.InterruptedException thrown if Threads are interrupted.
    */
   public void shutDown(int shutdownTimeout) throws InterruptedException {
     _isRunning = false;

java/org/rocksdb/TableFormatConfig.java

@@ -12,9 +12,11 @@ package org.rocksdb;
  */
 public abstract class TableFormatConfig {
   /**
-   * This function should only be called by Options.setTableFormatConfig(),
+   * <p>This function should only be called by Options.setTableFormatConfig(),
    * which will create a c++ shared-pointer to the c++ TableFactory
-   * that associated with the Java TableFormatConfig.
+   * that associated with the Java TableFormatConfig.</p>
+   *
+   * @return native handle address to native table instance.
    */
   abstract protected long newTableFactoryHandle();
 }

java/org/rocksdb/WriteBatch.java

@@ -23,11 +23,19 @@ package org.rocksdb;
  * external synchronization.
  */
 public class WriteBatch extends RocksObject {
+  /**
+   * Constructs a WriteBatch instance.
+   */
   public WriteBatch() {
     super();
     newWriteBatch(0);
   }
 
+  /**
+   * Constructs a WriteBatch instance with a given size.
+   *
+   * @param reserved_bytes reserved size for WriteBatch
+   */
   public WriteBatch(int reserved_bytes) {
     nativeHandle_ = 0;
     newWriteBatch(reserved_bytes);
@@ -35,19 +43,29 @@ public class WriteBatch extends RocksObject {
 
   /**
    * Returns the number of updates in the batch.
+   *
+   * @return number of items in WriteBatch
    */
   public native int count();
 
   /**
-   * Store the mapping "key->value" in the database.
+   * <p>Store the mapping "key-&gt;value" in the database.</p>
+   *
+   * @param key the specified key to be inserted.
+   * @param value the value associated with the specified key.
    */
   public void put(byte[] key, byte[] value) {
     put(key, key.length, value, value.length);
   }
 
   /**
-   * Store the mapping "key-&gt;value" within given column
-   * family.
+   * <p>Store the mapping "key-&gt;value" within given column
+   * family.</p>
+   *
+   * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
+   *     instance
+   * @param key the specified key to be inserted.
+   * @param value the value associated with the specified key.
    */
   public void put(ColumnFamilyHandle columnFamilyHandle,
       byte[] key, byte[] value) {
@@ -56,16 +74,25 @@ public class WriteBatch extends RocksObject {
   }
 
   /**
-   * Merge "value" with the existing value of "key" in the database.
-   * "key-&gt;merge(existing, value)"
+   * <p>Merge "value" with the existing value of "key" in the database.
+   * "key-&gt;merge(existing, value)"</p>
+   *
+   * @param key the specified key to be merged.
+   * @param value the value to be merged with the current value for
+   * the specified key.
    */
   public void merge(byte[] key, byte[] value) {
     merge(key, key.length, value, value.length);
   }
 
   /**
-   * Merge "value" with the existing value of "key" in given column family.
-   * "key-&gt;merge(existing, value)"
+   * <p>Merge "value" with the existing value of "key" in given column family.
+   * "key-&gt;merge(existing, value)"</p>
+   *
+   * @param columnFamilyHandle {@link ColumnFamilyHandle} instance
+   * @param key the specified key to be merged.
+   * @param value the value to be merged with the current value for
+   * the specified key.
    */
   public void merge(ColumnFamilyHandle columnFamilyHandle,
       byte[] key, byte[] value) {
@@ -74,14 +101,19 @@ public class WriteBatch extends RocksObject {
   }
 
   /**
-   * If the database contains a mapping for "key", erase it.  Else do nothing.
+   * <p>If the database contains a mapping for "key", erase it.  Else do nothing.</p>
+   *
+   * @param key Key to delete within database
    */
   public void remove(byte[] key) {
     remove(key, key.length);
   }
 
   /**
-   * If column family contains a mapping for "key", erase it.  Else do nothing.
+   * <p>If column family contains a mapping for "key", erase it.  Else do nothing.</p>
+   *
+   * @param columnFamilyHandle {@link ColumnFamilyHandle} instance
+   * @param key Key to delete within database
    */
   public void remove(ColumnFamilyHandle columnFamilyHandle, byte[] key) {
     remove(key, key.length, columnFamilyHandle.nativeHandle_);
@@ -98,6 +130,8 @@ public class WriteBatch extends RocksObject {
    *
    * Example application: add timestamps to the transaction log for use in
    * replication.
+   *
+   * @param blob binary object to be inserted
    */
   public void putLogData(byte[] blob) {
     putLogData(blob, blob.length);
@@ -166,6 +200,9 @@ public class WriteBatch extends RocksObject {
      * iteration is halted. Otherwise, it continues
      * iterating. The default implementation always
      * returns true.
+     *
+     * @return boolean value indicating if the
+     *     iteration is halted.
      */
     public boolean shouldContinue() {
       return true;

java/org/rocksdb/WriteOptions.java

@@ -12,6 +12,9 @@ package org.rocksdb;
  * c++ side memory before a WriteOptions instance runs out of scope.
  */
 public class WriteOptions extends RocksObject {
+  /**
+   * Construct WriteOptions instance.
+   */
   public WriteOptions() {
     super();
     newWriteOptions();
@@ -64,6 +67,8 @@ public class WriteOptions extends RocksObject {
    * crash semantics as the "write()" system call.  A DB write
    * with sync==true has similar crash semantics to a "write()"
    * system call followed by "fdatasync()".
+   *
+   * @return boolean value indicating if sync is active.
    */
   public boolean sync() {
     return sync(nativeHandle_);
@@ -85,6 +90,8 @@ public class WriteOptions extends RocksObject {
   /**
    * If true, writes will not first go to the write ahead log,
    * and the write may got lost after a crash.
+   *
+   * @return boolean value indicating if WAL is disabled.
    */
   public boolean disableWAL() {
     return disableWAL(nativeHandle_);

java/org/rocksdb/test/AbstractComparatorTest.java

@@ -36,6 +36,8 @@ public abstract class AbstractComparatorTest {
    *
    * @param db_path A path where we can store database
    *                files temporarily
+   *
+   * @throws java.io.IOException if IO error happens.
    */
   public void testRoundtrip(final Path db_path) throws IOException {
 

java/org/rocksdb/test/PlatformRandomHelper.java

@@ -14,6 +14,8 @@ import java.util.Random;
 public class PlatformRandomHelper {
     /**
      * Determine if OS is 32-Bit/64-Bit
+     *
+     * @return boolean value indicating if operating system is 64 Bit.
      */
     public static boolean isOs64Bit(){
       boolean is64Bit = false;
@@ -27,6 +29,8 @@ public class PlatformRandomHelper {
 
     /**
      * Factory to get a platform specific Random instance
+     *
+     * @return {@link java.util.Random} instance.
      */
     public static Random getPlatformSpecificRandomFactory(){
       if (isOs64Bit()) {

java/org/rocksdb/util/Environment.java

@@ -5,17 +5,17 @@ public class Environment {
   private static String ARCH = System.getProperty("os.arch").toLowerCase();
 
   public static boolean isWindows() {
-    return (OS.indexOf("win") >= 0);
+    return (OS.contains("win"));
   }
 
   public static boolean isMac() {
-    return (OS.indexOf("mac") >= 0);
+    return (OS.contains("mac"));
   }
 
   public static boolean isUnix() {
-    return (OS.indexOf("nix") >= 0 ||
-            OS.indexOf("nux") >= 0 ||
-            OS.indexOf("aix") >= 0);
+    return (OS.contains("nix") ||
+        OS.contains("nux") ||
+        OS.contains("aix"));
   }
 
   public static boolean is64Bit() {