Package org.apache.hadoop.io

Generic i/o code for use when reading and writing data to the network, to databases, and to files.

See: Description

Interface Summary

Interface	Description
ByteBufferPool
Closeable	Deprecated use java.io.Closeable
RawComparator<T>	A Comparator that operates directly on byte representations of objects.
Stringifier<T>	Stringifier interface offers two methods to convert an object to a string representation and restore the object given its string representation.
Writable	A serializable object which implements a simple, efficient, serialization protocol, based on DataInput and DataOutput.
WritableComparable<T>	A Writable which is also Comparable.
WritableFactory	A factory for a class of Writable.

Class Summary

Class	Description
AbstractMapWritable	Abstract base class for MapWritable and SortedMapWritable Unlike org.apache.nutch.crawl.MapWritable, this class allows creation of MapWritable<Writable, MapWritable> so the CLASS_TO_ID and ID_TO_CLASS maps travel with the class instead of being static.
ArrayFile	A dense file-based mapping from integers to values.
ArrayPrimitiveWritable	This is a wrapper class.
ArrayWritable	A Writable for arrays containing instances of a class.
BinaryComparable	Interface supported by WritableComparable types supporting ordering/permutation by a representative set of bytes.
BloomMapFile	This class extends MapFile and provides very much the same functionality.
BooleanWritable	A WritableComparable for booleans.
BytesWritable	A byte sequence that is usable as a key or value.
ByteWritable	A WritableComparable for a single byte.
CompressedWritable	A base-class for Writables which store themselves compressed and lazily inflate on field access.
DataOutputOutputStream	OutputStream implementation that wraps a DataOutput.
DefaultStringifier<T>	DefaultStringifier is the default implementation of the Stringifier interface which stringifies the objects using base64 encoding of the serialized version of the objects.
DoubleWritable	Writable for Double values.
ElasticByteBufferPool	This is a simple ByteBufferPool which just creates ByteBuffers as needed.
EnumSetWritable<E extends Enum<E>>	A Writable wrapper for EnumSet.
FloatWritable	A WritableComparable for floats.
GenericWritable	A wrapper for Writable instances.
IntWritable	A WritableComparable for ints.
IOUtils	An utility class for I/O related functionality.
LongWritable	A WritableComparable for longs.
MapFile	A file-based map from keys to values.
MapWritable	A Writable Map.
MD5Hash	A Writable for MD5 hash values.
NullWritable	Singleton Writable with no data.
ObjectWritable	A polymorphic Writable that writes an instance with it's class name.
SequenceFile	SequenceFiles are flat files consisting of binary key/value pairs.
SetFile	A file-based set of keys.
ShortWritable	A WritableComparable for shorts.
SortedMapWritable<K extends WritableComparable<? super K>>	A Writable SortedMap.
Text	This class stores text using standard UTF8 encoding.
TwoDArrayWritable	A Writable for 2D arrays containing a matrix of instances of a class.
VersionedWritable	A base class for Writables that provides version checking.
VIntWritable	A WritableComparable for integer values stored in variable-length format.
VLongWritable	A WritableComparable for longs in a variable-length format.
WritableComparator	A Comparator for WritableComparables.
WritableFactories	Factories for non-public writables.
WritableUtils

Exception Summary

Exception	Description
MultipleIOException	Encapsulate a list of IOException into an IOException
VersionMismatchException	Thrown by VersionedWritable.readFields(DataInput) when the version of an object being read does not match the current implementation version as returned by VersionedWritable.getVersion().

Package org.apache.hadoop.io Description

Generic i/o code for use when reading and writing data to the network, to databases, and to files.