JobID (Hadoop 0.20.2+320 API)
Date: 2010-06-28

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## org.apache.hadoop.mapreduce
Class JobID

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

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

Direct Known Subclasses:
  JobID

    public class JobID

extends ID
implements Comparable<ID>

JobID represents the immutable and unique identifier for the job. JobID consists of two parts. First part represents the jobtracker identifier, so that jobID to jobtracker map is defined. For cluster setup this string is the jobtracker start time, for local setting, it is "local". Second part of the JobID is the job number.
An example JobID is : `job_200707121733_0003` , which represents the third job running at the jobtracker started at `200707121733`.

Applications should never construct or parse JobID strings, but rather use appropriate constructors or `forName(String)` method.

See Also:
  `TaskID`, `TaskAttemptID`, `JobTracker.getNewJobId()`, `JobTracker.getStartTime()`

Field Summary
`protected static NumberFormat` | `idFormat`
`protected static String` | `JOB`

Fields inherited from class org.apache.hadoop.mapreduce.ID
`id, SEPARATOR`

Constructor Summary
`JobID()`
`JobID(String jtIdentifier, int id)` Constructs a JobID object

Method Summary
`StringBuilder` | `appendTo(StringBuilder builder)` Add the stuff after the "job" prefix to the given builder.
`int` | `compareTo(ID o)` Compare JobIds by first jtIdentifiers, then by job numbers
`boolean` | `equals(Object o)`
`static JobID` | `forName(String str)` Construct a JobId object from given string
`String` | `getJtIdentifier()`
`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 org.apache.hadoop.mapreduce.ID
`getId`

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

Field Detail

### JOB

    protected static final String JOB

See Also:
  Constant Field Values

### idFormat

    protected static final NumberFormat idFormat

Constructor Detail

### JobID

    public JobID(String jtIdentifier,
                 int id)

  Constructs a JobID object

  Parameters:
    `jtIdentifier` - jobTracker identifier
    `id` - job number

### JobID

    public JobID()

Method Detail

### getJtIdentifier

    public String getJtIdentifier()

### equals

    public boolean equals(Object o)

  Overrides:
    `equals` in class `ID`

### compareTo

    public int compareTo(ID o)

  Compare JobIds by first jtIdentifiers, then by job numbers

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

### appendTo

    public StringBuilder appendTo(StringBuilder builder)

  Add the stuff after the "job" prefix to the given builder. This is useful, because the sub-ids use this substring at the start of their string.

  Parameters:
    `builder` - the builder to append to
  Returns:
    the builder that was passed in

### hashCode

    public int hashCode()

  Overrides:
    `hashCode` in class `ID`

### toString

    public String toString()

  Overrides:
    `toString` in class `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`
  Overrides:
    `readFields` in class `ID`
  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`
  Overrides:
    `write` in class `ID`
  Parameters:
    `out` - `DataOuput` to serialize this object into.
  Throws:
    `IOException`

### forName

    public static JobID forName(String str)
                         throws IllegalArgumentException

  Construct a JobId object from given string

  Returns:
    constructed JobId object or null if the given String is null
  Throws:
    `IllegalArgumentException` - if the given string is malformed

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Copyright © 2009 The Apache Software Foundation