## org.apache.hadoop.io
Class BytesWritable

    java.lang.Object
      org.apache.hadoop.io.BinaryComparable
          org.apache.hadoop.io.BytesWritable

All Implemented Interfaces:
  Comparable<BinaryComparable>, Writable, WritableComparable<BinaryComparable>

Direct Known Subclasses:
  TypedBytesWritable

    public class BytesWritable

extends BinaryComparable
implements WritableComparable<BinaryComparable>

A byte sequence that is usable as a key or value. It is resizable and distinguishes between the size of the seqeunce and the current capacity. The hash function is the front of the md5 of the buffer. The sort order is the same as memcmp.

Nested Class Summary
`static class` `BytesWritable.Comparator` A Comparator optimized for BytesWritable.

Constructor Summary
`BytesWritable()` Create a zero-size sequence.
`BytesWritable(byte[] bytes)` Create a BytesWritable using the byte array as the initial value.

Method Summary
`boolean` `equals(Object right_obj)` Are the two byte sequences equal?
`byte[]` `get()` Deprecated. Use `getBytes()` instead.
`byte[]` `getBytes()` Get the data from the BytesWritable.
`int` `getCapacity()` Get the capacity, which is the maximum size that could handled without resizing the backing storage.
`int` `getLength()` Get the current size of the buffer.
`int` `getSize()` Deprecated. Use `getLength()` instead.
`int` `hashCode()` Return a hash of the bytes returned from {#getBytes()}.
`void` `readFields(DataInput in)` Deserialize the fields of this object from `in`.
`void` `set(byte[] newData, int offset, int length)` Set the value to a copy of the given byte range
`void` `set(BytesWritable newData)` Set the BytesWritable to the contents of the given newData.
`void` `setCapacity(int new_cap)` Change the capacity of the backing storage.
`void` `setSize(int size)` Change the size of the buffer.
`String` `toString()` Generate the stream of bytes as hex pairs separated by ' '.
`void` `write(DataOutput out)` Serialize the fields of this object to `out`.

Methods inherited from class org.apache.hadoop.io.BinaryComparable
`compareTo, compareTo`

Methods inherited from class java.lang.Object
`clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

Methods inherited from interface java.lang.Comparable
`compareTo`

Constructor Detail

### BytesWritable

    public BytesWritable()

  Create a zero-size sequence.

### BytesWritable

    public BytesWritable(byte[] bytes)

  Create a BytesWritable using the byte array as the initial value.

  Parameters:
    `bytes` - This array becomes the backing storage for the object.

Method Detail

### getBytes

    public byte[] getBytes()

  Get the data from the BytesWritable.

  Specified by:
    `getBytes` in class `BinaryComparable`
  Returns:
    The data is only valid between 0 and getLength() - 1.

### get

    @Deprecated
    public byte[] get()

  Deprecated. Use `getBytes()` instead.

  Get the data from the BytesWritable.

### getLength

    public int getLength()

  Get the current size of the buffer.

  Specified by:
    `getLength` in class `BinaryComparable`

### getSize

    @Deprecated
    public int getSize()

  Deprecated. Use `getLength()` instead.

  Get the current size of the buffer.

### setSize

    public void setSize(int size)

  Change the size of the buffer. The values in the old range are preserved and any new values are undefined. The capacity is changed if it is necessary.

  Parameters:
    `size` - The new number of bytes

### getCapacity

    public int getCapacity()

  Get the capacity, which is the maximum size that could handled without resizing the backing storage.

  Returns:
    The number of bytes

### setCapacity

    public void setCapacity(int new_cap)

  Change the capacity of the backing storage. The data is preserved.

  Parameters:
    `new_cap` - The new capacity in bytes.

### set

    public void set(BytesWritable newData)

  Set the BytesWritable to the contents of the given newData.

  Parameters:
    `newData` - the value to set this BytesWritable to.

### set

    public void set(byte[] newData,
                    int offset,
                    int length)

  Set the value to a copy of the given byte range

  Parameters:
    `newData` - the new values to copy in
    `offset` - the offset in newData to start at
    `length` - the number of bytes to copy

### readFields

    public void readFields(DataInput in)
                    throws IOException

  Description copied from interface: `Writable`
  Deserialize the fields of this object from `in`.

  For efficiency, implementations should attempt to re-use storage in the existing object where possible.

  Specified by:
    `readFields` in interface `Writable`
  Parameters:
    `in` - `DataInput` to deseriablize this object from.
  Throws:
    `IOException`

### write

    public void write(DataOutput out)
               throws IOException

  Description copied from interface: `Writable`
  Serialize the fields of this object to `out`.

  Specified by:
    `write` in interface `Writable`
  Parameters:
    `out` - `DataOuput` to serialize this object into.
  Throws:
    `IOException`

### hashCode

    public int hashCode()

  Description copied from class: `BinaryComparable`
  Return a hash of the bytes returned from {#getBytes()}.

  Overrides:
    `hashCode` in class `BinaryComparable`
  See Also:
    `WritableComparator.hashBytes(byte[],int)`

### equals

    public boolean equals(Object right_obj)

  Are the two byte sequences equal?

  Overrides:
    `equals` in class `BinaryComparable`

### toString

    public String toString()

  Generate the stream of bytes as hex pairs separated by ' '.

  Overrides:
    `toString` in class `Object`

Copyright © 2009 The Apache Software Foundation