org.apache.hadoop.io
Interfaces 
ByteBufferPool
Closeable
RawComparator
Stringifier
Writable
WritableComparable
WritableFactory
Classes 
AbstractMapWritable
ArrayFile
ArrayPrimitiveWritable
ArrayWritable
BinaryComparable
BloomMapFile
BooleanWritable
BytesWritable
ByteWritable
CompressedWritable
DataOutputOutputStream
DefaultStringifier
DoubleWritable
ElasticByteBufferPool
EnumSetWritable
FloatWritable
GenericWritable
IntWritable
IOUtils
LongWritable
MapFile
MapWritable
MD5Hash
NullWritable
ObjectWritable
SequenceFile
SetFile
ShortWritable
SortedMapWritable
Text
TwoDArrayWritable
VersionedWritable
VIntWritable
VLongWritable
WritableComparator
WritableFactories
WritableUtils
Exceptions 
MultipleIOException
VersionMismatchException