CompressedWritable (Hadoop 1.2.1 API)
Date: 2013-07-22

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## org.apache.hadoop.io
Class CompressedWritable

    java.lang.Object
      org.apache.hadoop.io.CompressedWritable

All Implemented Interfaces:
  Writable

    public abstract class CompressedWritable

extends Object
implements Writable

A base-class for Writables which store themselves compressed and lazily inflate on field access. This is useful for large objects whose fields are not be altered during a map or reduce operation: leaving the field data compressed makes copying the instance from one file to another much faster.

Constructor Summary
`CompressedWritable()`

Method Summary
`protected void` | `ensureInflated()` Must be called by all methods which access fields to ensure that the data has been uncompressed.
`void` | `readFields(DataInput in)` Deserialize the fields of this object from `in`.
`protected abstract void` | `readFieldsCompressed(DataInput in)` Subclasses implement this instead of `readFields(DataInput)`.
`void` | `write(DataOutput out)` Serialize the fields of this object to `out`.
`protected abstract void` | `writeCompressed(DataOutput out)` Subclasses implement this instead of `write(DataOutput)`.

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

Constructor Detail

### CompressedWritable

    public CompressedWritable()

Method Detail

### readFields

    public final 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`

### ensureInflated

    protected void ensureInflated()

  Must be called by all methods which access fields to ensure that the data has been uncompressed.

### readFieldsCompressed

    protected abstract void readFieldsCompressed(DataInput in)
                                          throws IOException

  Subclasses implement this instead of `readFields(DataInput)`.

  Throws:
    `IOException`

### write

    public final 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`

### writeCompressed

    protected abstract void writeCompressed(DataOutput out)
                                     throws IOException

  Subclasses implement this instead of `write(DataOutput)`.

  Throws:
    `IOException`

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