Uses of Interface
org.apache.hadoop.io.Writable

Packages that use Writable

org.apache.hadoop.contrib.utils.join
org.apache.hadoop.dfs	A distributed implementation of FileSystem.
org.apache.hadoop.examples	Hadoop example code.
org.apache.hadoop.io	Generic i/o code for use when reading and writing data to the network, to databases, and to files.
org.apache.hadoop.ipc	Tools to help define network clients and servers.
org.apache.hadoop.mapred	A system for scalable, fault-tolerant, distributed computation over large data collections.
org.apache.hadoop.mapred.lib	Library of generally useful mappers, reducers, and partitioners.
org.apache.hadoop.mapred.lib.aggregate	Classes for performing various counting and aggregations.
org.apache.hadoop.record	Hadoop record I/O contains classes and a record description language translator for simplifying serialization and deserialization of records in a language-neutral manner.
org.apache.hadoop.streaming
org.apache.hadoop.tools
org.apache.hadoop.util	Common utilities.

Uses of Writable in org.apache.hadoop.contrib.utils.join

Classes in org.apache.hadoop.contrib.utils.join that implement Writable

class

TaggedMapOutput This abstract class serves as the base class for the values that flow from the mappers to the reducers in a data join job.

Methods in org.apache.hadoop.contrib.utils.join that return Writable

abstract Writable

TaggedMapOutput.getData()

Methods in org.apache.hadoop.contrib.utils.join with parameters of type Writable

protected abstract TaggedMapOutput	DataJoinMapperBase.generateTaggedMapOutput(Writable value) Generate a tagged map output value.
void	DataJoinMapperBase.map(WritableComparable key, Writable value, OutputCollector output, Reporter reporter)
void	DataJoinReducerBase.map(WritableComparable arg0, Writable arg1, OutputCollector arg2, Reporter arg3)

Uses of Writable in org.apache.hadoop.dfs

Classes in org.apache.hadoop.dfs that implement Writable

class	DatanodeDescriptor DatanodeDescriptor tracks stats on a given DataNode, such as available storage capacity, last update time, etc., and maintains a set of blocks stored on the datanode.
class	DatanodeID DatanodeID is composed of the data node name (hostname:portNumber) and the data storage ID, which it currently represents.
class	DatanodeInfo DatanodeInfo represents the status of a DataNode.

Uses of Writable in org.apache.hadoop.examples

Methods in org.apache.hadoop.examples with parameters of type Writable

void	PiEstimator.PiMapper.map(WritableComparable key, Writable val, OutputCollector out, Reporter reporter) Map method.
void	WordCount.MapClass.map(WritableComparable key, Writable value, OutputCollector output, Reporter reporter)

Uses of Writable in org.apache.hadoop.io

Subinterfaces of Writable in org.apache.hadoop.io

interface

WritableComparable An interface which extends both Writable and Comparable.

Classes in org.apache.hadoop.io that implement Writable

class	ArrayWritable A Writable for arrays containing instances of a class.
class	BooleanWritable A WritableComparable for booleans.
class	BytesWritable A byte sequence that is usable as a key or value.
class	CompressedWritable A base-class for Writables which store themselves compressed and lazily inflate on field access.
class	FloatWritable A WritableComparable for floats.
class	GenericWritable A wrapper for Writable instances.
class	IntWritable A WritableComparable for ints.
class	LongWritable A WritableComparable for longs.
class	MD5Hash A Writable for MD5 hash values.
class	NullWritable Singleton Writable with no data.
class	ObjectWritable A polymorphic Writable that writes an instance with it's class name.
static class	SequenceFile.Metadata The class encapsulating with the metadata of a file.
class	Text This class stores text using standard UTF8 encoding.
class	TwoDArrayWritable A Writable for 2D arrays containing a matrix of instances of a class.
class	UTF8 Deprecated. replaced by Text
class	VersionedWritable A base class for Writables that provides version checking.
class	VIntWritable A WritableComparable for integer values stored in variable-length format.
class	VLongWritable A WritableComparable for longs in a variable-length format.

Methods in org.apache.hadoop.io that return Writable

static Writable	WritableUtils.clone(Writable orig, JobConf conf) Make a copy of a writable object using serialization to a buffer.
Writable	GenericWritable.get() Return the wrapped instance.
Writable[]	ArrayWritable.get()
Writable[][]	TwoDArrayWritable.get()
Writable	ArrayFile.Reader.get(long n, Writable value) Return the nth value in the file.
Writable	MapFile.Reader.get(WritableComparable key, Writable val) Return the value for the named key, or null if none exists.
Writable	WritableFactory.newInstance() Return a new instance.
static Writable	WritableFactories.newInstance(Class c) Create a new instance of a class with a defined factory.
static Writable	WritableFactories.newInstance(Class c, Configuration conf) Create a new instance of a class with a defined factory.
Writable	ArrayFile.Reader.next(Writable value) Read and return the next value in the file.

Methods in org.apache.hadoop.io with parameters of type Writable

void	ArrayFile.Writer.append(Writable value) Append a value to the file.
void	MapFile.Writer.append(WritableComparable key, Writable val) Append a key/value pair to the map.
void	SequenceFile.Writer.append(Writable key, Writable val) Append a key/value pair.
static Writable	WritableUtils.clone(Writable orig, JobConf conf) Make a copy of a writable object using serialization to a buffer.
Writable	ArrayFile.Reader.get(long n, Writable value) Return the nth value in the file.
Writable	MapFile.Reader.get(WritableComparable key, Writable val) Return the value for the named key, or null if none exists.
WritableComparable	MapFile.Reader.getClosest(WritableComparable key, Writable val) Finds the record that is the closest match to the specified key.
void	SequenceFile.Reader.getCurrentValue(Writable val) Get the 'value' corresponding to the last read 'key'.
boolean	SequenceFile.Reader.next(Writable key) Read the next key in the file into key, skipping its value.
Writable	ArrayFile.Reader.next(Writable value) Read and return the next value in the file.
boolean	MapFile.Reader.next(WritableComparable key, Writable val) Read the next key/value pair in the map into key and val.
boolean	SequenceFile.Reader.next(Writable key, Writable val) Read the next key/value pair in the file into key and val.
void	GenericWritable.set(Writable obj) Set the instance that is wrapped.
void	ArrayWritable.set(Writable[] values)
void	TwoDArrayWritable.set(Writable[][] values)

Constructors in org.apache.hadoop.io with parameters of type Writable

ArrayWritable(Class valueClass, Writable[] values)

TwoDArrayWritable(Class valueClass, Writable[][] values)

Uses of Writable in org.apache.hadoop.ipc

Methods in org.apache.hadoop.ipc that return Writable

abstract Writable	Server.call(Writable param) Called for each call.
Writable	RPC.Server.call(Writable param)
Writable[]	Client.call(Writable[] params, InetSocketAddress[] addresses) Makes a set of calls in parallel.
Writable	Client.call(Writable param, InetSocketAddress address) Make a call, passing param, to the IPC server running at address, returning the value.

Methods in org.apache.hadoop.ipc with parameters of type Writable

abstract Writable	Server.call(Writable param) Called for each call.
Writable	RPC.Server.call(Writable param)
Writable[]	Client.call(Writable[] params, InetSocketAddress[] addresses) Makes a set of calls in parallel.
Writable	Client.call(Writable param, InetSocketAddress address) Make a call, passing param, to the IPC server running at address, returning the value.

Uses of Writable in org.apache.hadoop.mapred

Subinterfaces of Writable in org.apache.hadoop.mapred

interface

InputSplit The description of the data for a single map task.

Classes in org.apache.hadoop.mapred that implement Writable

class	ClusterStatus Summarizes the size and current state of the cluster.
class	Counters A set of named counters.
class	FileSplit A section of an input file.
class	JobProfile A JobProfile is a MapReduce primitive.
class	JobStatus Describes the current status of a job.
class	TaskCompletionEvent This is used to track task completion events on job tracker.
class	TaskReport A report on the state of a task.

Methods in org.apache.hadoop.mapred that return Writable

Writable	SequenceFileRecordReader.createValue()
Writable	SequenceFileAsTextRecordReader.createValue()
Writable	LineRecordReader.createValue()
Writable	RecordReader.createValue() Create an object of the appropriate type to be used as the value.
static Writable	MapFileOutputFormat.getEntry(MapFile.Reader[] readers, Partitioner partitioner, WritableComparable key, Writable value) Get an entry from output generated by this class.

Methods in org.apache.hadoop.mapred that return types with arguments of type Writable

Class<? extends Writable>	JobConf.getMapOutputValueClass() Get the value class for the map output data.
Class<? extends Writable>	JobConf.getOutputValueClass()

Methods in org.apache.hadoop.mapred with parameters of type Writable

boolean	SequenceFileInputFilter.Filter.accept(Writable key) filter function Decide if a record should be filtered or not
boolean	SequenceFileInputFilter.RegexFilter.accept(Writable key) Filtering method If key matches the regex, return true; otherwise return false
boolean	SequenceFileInputFilter.PercentFilter.accept(Writable key) Filtering method If record# % frequency==0, return true; otherwise return false
boolean	SequenceFileInputFilter.MD5Filter.accept(Writable key) Filtering method If MD5(key) % frequency==0, return true; otherwise return false
void	OutputCollector.collect(WritableComparable key, Writable value) Adds a key/value pair to the output.
protected void	SequenceFileRecordReader.getCurrentValue(Writable value)
static Writable	MapFileOutputFormat.getEntry(MapFile.Reader[] readers, Partitioner partitioner, WritableComparable key, Writable value) Get an entry from output generated by this class.
int	Partitioner.getPartition(WritableComparable key, Writable value, int numPartitions) Returns the paritition number for a given entry given the total number of partitions.
void	Mapper.map(WritableComparable key, Writable value, OutputCollector output, Reporter reporter) Maps a single input key/value pair into intermediate key/value pairs.
protected boolean	SequenceFileRecordReader.next(Writable key)
boolean	SequenceFileRecordReader.next(Writable key, Writable value)
boolean	KeyValueLineRecordReader.next(Writable key, Writable value) Read key/value pair in a line.
boolean	SequenceFileAsTextRecordReader.next(Writable key, Writable value) Read key/value pair in a line.
boolean	LineRecordReader.next(Writable key, Writable value) Read a line.
boolean	RecordReader.next(Writable key, Writable value) Reads the next key/value pair.
void	TextOutputFormat.LineRecordWriter.write(WritableComparable key, Writable value)
void	RecordWriter.write(WritableComparable key, Writable value) Writes a key/value pair.

Method parameters in org.apache.hadoop.mapred with type arguments of type Writable

void	JobConf.setMapOutputValueClass(Class<? extends Writable> theClass) Set the value class for the map output data.
void	JobConf.setOutputValueClass(Class<? extends Writable> theClass)

Uses of Writable in org.apache.hadoop.mapred.lib

Methods in org.apache.hadoop.mapred.lib with parameters of type Writable

int	HashPartitioner.getPartition(WritableComparable key, Writable value, int numReduceTasks) Use Object.hashCode() to partition.
int	KeyFieldBasedPartitioner.getPartition(WritableComparable key, Writable value, int numReduceTasks) Use Object.hashCode() to partition.
void	FieldSelectionMapReduce.map(WritableComparable key, Writable val, OutputCollector output, Reporter reporter) The identify function.
void	IdentityMapper.map(WritableComparable key, Writable val, OutputCollector output, Reporter reporter) The identify function.
void	RegexMapper.map(WritableComparable key, Writable value, OutputCollector output, Reporter reporter)
void	InverseMapper.map(WritableComparable key, Writable value, OutputCollector output, Reporter reporter) The inverse function.
void	TokenCountMapper.map(WritableComparable key, Writable value, OutputCollector output, Reporter reporter)

Uses of Writable in org.apache.hadoop.mapred.lib.aggregate

Methods in org.apache.hadoop.mapred.lib.aggregate with parameters of type Writable

void	ValueAggregatorMapper.map(WritableComparable key, Writable value, OutputCollector output, Reporter reporter) the map function.
void	ValueAggregatorReducer.map(WritableComparable arg0, Writable arg1, OutputCollector arg2, Reporter arg3) Do nothing.
void	ValueAggregatorCombiner.map(WritableComparable arg0, Writable arg1, OutputCollector arg2, Reporter arg3) Do nothing.

Uses of Writable in org.apache.hadoop.record

Classes in org.apache.hadoop.record that implement Writable

class

Record Abstract class that is extended by generated classes.

Uses of Writable in org.apache.hadoop.streaming

Methods in org.apache.hadoop.streaming that return Writable

Writable

StreamBaseRecordReader.createValue()

Methods in org.apache.hadoop.streaming with parameters of type Writable

void	PipeMapper.map(WritableComparable key, Writable value, OutputCollector output, Reporter reporter)
abstract boolean	StreamBaseRecordReader.next(Writable key, Writable value) Read a record.
boolean	StreamXmlRecordReader.next(Writable key, Writable value)

Uses of Writable in org.apache.hadoop.tools

Methods in org.apache.hadoop.tools with parameters of type Writable

void	Logalyzer.LogRegexMapper.map(WritableComparable key, Writable value, OutputCollector output, Reporter reporter)

Uses of Writable in org.apache.hadoop.util

Methods in org.apache.hadoop.util with parameters of type Writable

void	CopyFiles.FSCopyFilesMapper.map(WritableComparable key, Writable value, OutputCollector out, Reporter reporter) Map method.
void	CopyFiles.HTTPCopyFilesMapper.map(WritableComparable key, Writable val, OutputCollector out, Reporter reporter)