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

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## org.apache.hadoop.mapreduce
Class ID

    java.lang.Object
      org.apache.hadoop.mapreduce.ID

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

Direct Known Subclasses:
  ID

    public abstract class ID

extends Object
implements WritableComparable<ID>

A general identifier, which internally stores the id as an integer. This is the super class of `JobID`, `TaskID` and `TaskAttemptID`.

See Also:
  `JobID`, `TaskID`, `TaskAttemptID`

Field Summary
`protected int` | `id`
`protected static char` | `SEPARATOR`

Constructor Summary
`protected` | `ID()`
`` | `ID(int id)` constructs an ID object from the given int

Method Summary
`int` | `compareTo(ID that)` Compare IDs by associated numbers
`boolean` | `equals(Object o)`
`int` | `getId()` returns the int which represents the identifier
`int` | `hashCode()`
`void` | `readFields(DataInput in)` Deserialize the fields of this object from `in`.
`String` | `toString()`
`void` | `write(DataOutput out)` Serialize the fields of this object to `out`.

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

Field Detail

### SEPARATOR

    protected static final char SEPARATOR

See Also:
  Constant Field Values

### id

    protected int id

Constructor Detail

### ID

    public ID(int id)

  constructs an ID object from the given int

### ID

    protected ID()

Method Detail

### getId

    public int getId()

  returns the int which represents the identifier

### toString

    public String toString()

  Overrides:
    `toString` in class `Object`

### hashCode

    public int hashCode()

  Overrides:
    `hashCode` in class `Object`

### equals

    public boolean equals(Object o)

  Overrides:
    `equals` in class `Object`

### compareTo

    public int compareTo(ID that)

  Compare IDs by associated numbers

  Specified by:
    `compareTo` in interface `Comparable<ID>`

### 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`

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Copyright © 2009 The Apache Software Foundation