| Name | Description | Type | Package | Framework |
| AbstractMapWritable | Abstract base class for MapWritable and SortedMapWritable Unlike org. | Class | org.apache.hadoop.io | Apache Hadoop |
| ArrayFile | A dense file-based mapping from integers to values. | Class | org.apache.hadoop.io | Apache Hadoop |
| ArrayPrimitiveWritable | This is a wrapper class. | Class | org.apache.hadoop.io | Apache Hadoop |
| ArrayWritable | A Writable for arrays containing instances of a class. | Class | org.apache.hadoop.io | Apache Hadoop |
| AvroReflectSerialization | Serialization for Avro Reflect classes. | Class | org.apache.hadoop.io.serializer.avro | Apache Hadoop |
| AvroSerialization | Base class for providing serialization to Avro types. | Class | org.apache.hadoop.io.serializer.avro | Apache Hadoop |
| AvroSpecificSerialization | Serialization for Avro Specific classes. | Class | org.apache.hadoop.io.serializer.avro | Apache Hadoop |
| BinaryComparable | Interface supported by WritableComparable types supporting ordering/permutation by a representative set of bytes. | Class | org.apache.hadoop.io | Apache Hadoop |
| BlockCompressorStream | A CompressorStream which works with 'block-based' based compression algorithms, as opposed to | Class | org.apache.hadoop.io.compress | Apache Hadoop |
| BlockDecompressorStream | A DecompressorStream which works with 'block-based' based compression algorithms, as opposed to | Class | org.apache.hadoop.io.compress | Apache Hadoop |
| BloomMapFile | This class extends MapFile and provides very much the same functionality. | Class | org.apache.hadoop.io | Apache Hadoop |
| BooleanWritable | A WritableComparable for booleans. | Class | org.apache.hadoop.io | Apache Hadoop |
| ByteBufferPool | Interface | org.apache.hadoop.io | Apache Hadoop | |
| BytesWritable | A byte sequence that is usable as a key or value. | Class | org.apache.hadoop.io | Apache Hadoop |
| ByteWritable | A WritableComparable for a single byte. | Class | org.apache.hadoop.io | Apache Hadoop |
| BZip2Codec | This class provides output and input streams for bzip2 compression and decompression. | Class | org.apache.hadoop.io.compress | Apache Hadoop |
| CodecPool | A global compressor/decompressor pool used to save and reuse (possibly native) compression/decompression codecs. | Class | org.apache.hadoop.io.compress | Apache Hadoop |
| CompressedWritable | A base-class for Writables which store themselves compressed and lazily inflate on field access. | Class | org.apache.hadoop.io | Apache Hadoop |
| CompressionCodec | This class encapsulates a streaming compression/decompression pair. | Interface | org.apache.hadoop.io.compress | Apache Hadoop |
| CompressionCodecFactory | A factory that will find the correct codec for a given filename. | Class | org.apache.hadoop.io.compress | Apache Hadoop |
| CompressionInputStream | A compression input stream. | Class | org.apache.hadoop.io.compress | Apache Hadoop |
| CompressionOutputStream | A compression output stream. | Class | org.apache.hadoop.io.compress | Apache Hadoop |
| Compressor | Specification of a stream-based 'compressor' which can be plugged into a CompressionOutputStream to compress data. | Interface | org.apache.hadoop.io.compress | Apache Hadoop |
| CompressorStream | Class | org.apache.hadoop.io.compress | Apache Hadoop | |
| DataOutputOutputStream | OutputStream implementation that wraps a DataOutput. | Class | org.apache.hadoop.io | Apache Hadoop |
| Decompressor | Specification of a stream-based 'de-compressor' which can be plugged into a CompressionInputStream to compress data. | Interface | org.apache.hadoop.io.compress | Apache Hadoop |
| DecompressorStream | Class | org.apache.hadoop.io.compress | Apache Hadoop | |
| DefaultCodec | Class | org.apache.hadoop.io.compress | Apache Hadoop | |
| DefaultStringifier | DefaultStringifier is the default implementation of the Stringifier interface which stringifies the objects using base64 encoding of the | Class | org.apache.hadoop.io | Apache Hadoop |
| DirectDecompressionCodec | This class encapsulates a codec which can decompress direct bytebuffers. | Interface | org.apache.hadoop.io.compress | Apache Hadoop |
| DirectDecompressor | Specification of a direct ByteBuffer 'de-compressor'. | Interface | org.apache.hadoop.io.compress | Apache Hadoop |
| DoubleWritable | Writable for Double values. | Class | org.apache.hadoop.io | Apache Hadoop |
| ElasticByteBufferPool | This is a simple ByteBufferPool which just creates ByteBuffers as needed. | Class | org.apache.hadoop.io | Apache Hadoop |
| EnumSetWritable | A Writable wrapper for EnumSet. | Class | org.apache.hadoop.io | Apache Hadoop |
| FloatWritable | A WritableComparable for floats. | Class | org.apache.hadoop.io | Apache Hadoop |
| GenericWritable | A wrapper for Writable instances. | Class | org.apache.hadoop.io | Apache Hadoop |
| GzipCodec | This class creates gzip compressors/decompressors. | Class | org.apache.hadoop.io.compress | Apache Hadoop |
| IntWritable | A WritableComparable for ints. | Class | org.apache.hadoop.io | Apache Hadoop |
| IOUtils | An utility class for I/O related functionality. | Class | org.apache.hadoop.io | Apache Hadoop |
| JavaSerialization | An experimental Serialization for Java Serializable classes. | Class | org.apache.hadoop.io.serializer | Apache Hadoop |
| JavaSerializationComparator | A RawComparator that uses a JavaSerialization Deserializer to deserialize objects that are then compared via | Class | org.apache.hadoop.io.serializer | Apache Hadoop |
| LongWritable | A WritableComparable for longs. | Class | org.apache.hadoop.io | Apache Hadoop |
| MapFile | A file-based map from keys to values. | Class | org.apache.hadoop.io | Apache Hadoop |
| MapWritable | Class | org.apache.hadoop.io | Apache Hadoop | |
| MD5Hash | A Writable for MD5 hash values. | Class | org.apache.hadoop.io | Apache Hadoop |
| MetaBlockAlreadyExists | Exception - Meta Block with the same name already exists. | Class | org.apache.hadoop.io.file.tfile | Apache Hadoop |
| MetaBlockDoesNotExist | Exception - No such Meta Block with the given name. | Class | org.apache.hadoop.io.file.tfile | Apache Hadoop |
| MultipleIOException | Encapsulate a list of IOException into an IOExceptionSee Also:Serialized Form | Class | org.apache.hadoop.io | Apache Hadoop |
| NullWritable | Singleton Writable with no data. | Class | org.apache.hadoop.io | Apache Hadoop |
| ObjectWritable | A polymorphic Writable that writes an instance with it's class name. | Class | org.apache.hadoop.io | Apache Hadoop |
| RawComparable | Interface for objects that can be compared through RawComparator. | Interface | org.apache.hadoop.io.file.tfile | Apache Hadoop |
| RawComparator | A Comparator that operates directly on byte representations ofSee Also:DeserializerComparator | Interface | org.apache.hadoop.io | Apache Hadoop |
| SequenceFile | SequenceFiles are flat files consisting of binary key/value SequenceFile provides SequenceFile. | Class | org.apache.hadoop.io | Apache Hadoop |
| SetFile | A file-based set of keys. | Class | org.apache.hadoop.io | Apache Hadoop |
| ShortWritable | A WritableComparable for shorts. | Class | org.apache.hadoop.io | Apache Hadoop |
| SortedMapWritable | A Writable SortedMap. | Class | org.apache.hadoop.io | Apache Hadoop |
| SplitCompressionInputStream | An InputStream covering a range of compressed data. | Class | org.apache.hadoop.io.compress | Apache Hadoop |
| SplittableCompressionCodec | This interface is meant to be implemented by those compression codecs which are capable to compress / de-compress a stream starting at any | Interface | org.apache.hadoop.io.compress | Apache Hadoop |
| Stringifier | Stringifier interface offers two methods to convert an object to a string representation and restore the object given its | Interface | org.apache.hadoop.io | Apache Hadoop |
| Text | This class stores text using standard UTF8 encoding. | Class | org.apache.hadoop.io | Apache Hadoop |
| TFile | A TFile is a container of key-value pairs. | Class | org.apache.hadoop.io.file.tfile | Apache Hadoop |
| TwoDArrayWritable | A Writable for 2D arrays containing a matrix of instances of a class. | Class | org.apache.hadoop.io | Apache Hadoop |
| Utils | Supporting Utility classes used by TFile, and shared by users of TFile. | Class | org.apache.hadoop.io.file.tfile | Apache Hadoop |
| VersionedWritable | A base class for Writables that provides version checking. | Class | org.apache.hadoop.io | Apache Hadoop |
| VersionMismatchException | Thrown by VersionedWritable. | Class | org.apache.hadoop.io | Apache Hadoop |
| VIntWritable | A WritableComparable for integer values stored in variable-length format. | Class | org.apache.hadoop.io | Apache Hadoop |
| VLongWritable | A WritableComparable for longs in a variable-length format. | Class | org.apache.hadoop.io | Apache Hadoop |
| Writable | A serializable object which implements a simple, efficient, serialization protocol, based on DataInput and DataOutput. | Interface | org.apache.hadoop.io | Apache Hadoop |
| WritableComparable | A Writable which is also Comparable. | Interface | org.apache.hadoop.io | Apache Hadoop |
| WritableComparator | A Comparator for WritableComparables. | Class | org.apache.hadoop.io | Apache Hadoop |
| WritableFactories | Factories for non-public writables. | Class | org.apache.hadoop.io | Apache Hadoop |
| WritableFactory | A factory for a class of Writable. | Interface | org.apache.hadoop.io | Apache Hadoop |
| WritableSerialization | A Serialization for Writables that delegates to Writable. | Class | org.apache.hadoop.io.serializer | Apache Hadoop |
| WritableUtils | Class | org.apache.hadoop.io | Apache Hadoop | |