Package org.apache.hadoop.io

Class MapWritable

java.lang.Object

org.apache.hadoop.io.AbstractMapWritable

org.apache.hadoop.io.MapWritable

All Implemented Interfaces:

Map<Writable,Writable>, Configurable, Writable

@Public
@Stable
public class MapWritable
extends AbstractMapWritable
implements Map<Writable,Writable>

A Writable Map.

Nested Class Summary

Nested classes/interfaces inherited from interface java.util.Map

Map.Entry<K extends Object,V extends Object>

Constructor Summary

Constructors

Constructor	Description
MapWritable()	Default constructor.
MapWritable(MapWritable other)	Copy constructor.

Method Summary

Modifier and Type	Method	Description
void	clear()
boolean	containsKey(Object key)
boolean	containsValue(Object value)
Set<Map.Entry<Writable,Writable>>	entrySet()
boolean	equals(Object obj)
Writable	get(Object key)
int	hashCode()
boolean	isEmpty()
Set<Writable>	keySet()
Writable	put(Writable key, Writable value)
void	putAll(Map<? extends Writable,? extends Writable> t)
void	readFields(DataInput in)	Deserialize the fields of this object from in.
Writable	remove(Object key)
int	size()
String	toString()
Collection<Writable>	values()
void	write(DataOutput out)	Serialize the fields of this object to out.

Methods inherited from class org.apache.hadoop.io.AbstractMapWritable

addToMap, copy, getClass, getConf, getId, setConf

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Map

compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, putIfAbsent, remove, replace, replace, replaceAll

Constructor Details

MapWritable

public MapWritable()

Default constructor.

MapWritable

public MapWritable(MapWritable other)

Copy constructor.

Parameters:

other - the map to copy from

Method Details

clear

public void clear()

Specified by:

clear in interface Map<Writable,Writable>

containsKey

public boolean containsKey(Object key)

Specified by:

containsKey in interface Map<Writable,Writable>

containsValue

public boolean containsValue(Object value)

Specified by:

containsValue in interface Map<Writable,Writable>

entrySet

public Set<Map.Entry<Writable,Writable>> entrySet()

Specified by:

entrySet in interface Map<Writable,Writable>

equals

public boolean equals(Object obj)

Specified by:

equals in interface Map<Writable,Writable>

Overrides:

equals in class Object

get

public Writable get(Object key)

Specified by:

get in interface Map<Writable,Writable>

hashCode

public int hashCode()

Specified by:

hashCode in interface Map<Writable,Writable>

Overrides:

hashCode in class Object

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Map<Writable,Writable>

keySet

public Set<Writable> keySet()

Specified by:

keySet in interface Map<Writable,Writable>

put

public Writable put(Writable key,
 Writable value)

Specified by:

put in interface Map<Writable,Writable>

putAll

public void putAll(Map<? extends Writable,? extends Writable> t)

Specified by:

putAll in interface Map<Writable,Writable>

remove

public Writable remove(Object key)

Specified by:

remove in interface Map<Writable,Writable>

size

public int size()

Specified by:

size in interface Map<Writable,Writable>

values

public Collection<Writable> values()

Specified by:

values in interface Map<Writable,Writable>

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 AbstractMapWritable

Parameters:

out - DataOuput to serialize this object into.

Throws:

IOException - any other problem for write.

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 AbstractMapWritable

Parameters:

in - DataInput to deseriablize this object from.

Throws:

IOException - any other problem for readFields.

toString

public String toString()

Overrides:

toString in class Object