org.apache.hadoop.io

Class ObjectWritable

java.lang.Object

org.apache.hadoop.io.ObjectWritable

All Implemented Interfaces:

Configurable, Writable

Direct Known Subclasses:

MetaWrapper

public class ObjectWritable
extends Object
implements Writable, Configurable

A polymorphic Writable that writes an instance with it's class name. Handles arrays, strings and primitive types without a Writable wrapper.

Constructor Summary

Constructors

Constructor and Description
ObjectWritable()
ObjectWritable(Class declaredClass, Object instance)
ObjectWritable(Object instance)

Method Summary

Modifier and Type	Method and Description
Object	get() Return the instance, or null if none.
Configuration	getConf() Return the configuration used by this object.
Class	getDeclaredClass() Return the class this is meant to be.
void	readFields(DataInput in) Reads the fields of this object from in.
static Object	readObject(DataInput in, Configuration conf) Read a Writable, String, primitive type, or an array of the preceding.
static Object	readObject(DataInput in, ObjectWritable objectWritable, Configuration conf) Read a Writable, String, primitive type, or an array of the preceding.
void	set(Object instance) Reset the instance.
void	setConf(Configuration conf) Set the configuration to be used by this object.
void	write(DataOutput out) Writes the fields of this object to out.
static void	writeObject(DataOutput out, Object instance, Class declaredClass, Configuration conf) Write a Writable, String, primitive type, or an array of the preceding.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ObjectWritable

public ObjectWritable()

ObjectWritable

public ObjectWritable(Object instance)

ObjectWritable

public ObjectWritable(Class declaredClass,
                      Object instance)

Method Detail

get

public Object get()

Return the instance, or null if none.

getDeclaredClass

public Class getDeclaredClass()

Return the class this is meant to be.

set

public void set(Object instance)

Reset the instance.

readFields

public void readFields(DataInput in)
                throws IOException

Description copied from interface: Writable

Reads 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

Throws:

IOException

write

public void write(DataOutput out)
           throws IOException

Description copied from interface: Writable

Writes the fields of this object to out.

Specified by:

write in interface Writable

Throws:

IOException

writeObject

public static void writeObject(DataOutput out,
                               Object instance,
                               Class declaredClass,
                               Configuration conf)
                        throws IOException

Write a Writable, String, primitive type, or an array of the preceding.

Throws:

IOException

readObject

public static Object readObject(DataInput in,
                                Configuration conf)
                         throws IOException

Read a Writable, String, primitive type, or an array of the preceding.

Throws:

IOException

readObject

public static Object readObject(DataInput in,
                                ObjectWritable objectWritable,
                                Configuration conf)
                         throws IOException

Read a Writable, String, primitive type, or an array of the preceding.

Throws:

IOException

setConf

public void setConf(Configuration conf)

Description copied from interface: Configurable

Set the configuration to be used by this object.

Specified by:

setConf in interface Configurable

getConf

public Configuration getConf()

Description copied from interface: Configurable

Return the configuration used by this object.

Specified by:

getConf in interface Configurable