Added in API level 1

Summary: Ctors | Methods | Inherited Methods

Inflater

public class Inflater
extends Object

java.lang.Object
↳	java.util.zip.Inflater

---

This class provides support for general purpose decompression using the popular ZLIB compression library. The ZLIB compression library was initially developed as part of the PNG graphics standard and is not protected by patents. It is fully described in the specifications at the java.util.zip package description.

This class inflates sequences of ZLIB compressed bytes. The input byte sequence is provided in either byte array or byte buffer, via one of the setInput() methods. The output byte sequence is written to the output byte array or byte buffer passed to the deflate() methods.

The following code fragment demonstrates a trivial compression and decompression of a string using Deflater and Inflater.

 try {
     // Encode a String into bytes
     String inputString = "blahblahblah\u20ac\u20ac";
     byte[] input = inputString.getBytes("UTF-8");

     // Compress the bytes
     byte[] output = new byte[100];
     Deflater compresser = new Deflater();
     compresser.setInput(input);
     compresser.finish();
     int compressedDataLength = compresser.deflate(output);

     // Decompress the bytes
     Inflater decompresser = new Inflater();
     decompresser.setInput(output, 0, compressedDataLength);
     byte[] result = new byte[100];
     int resultLength = decompresser.inflate(result);
     decompresser.end();

     // Decode the bytes into a String
     String outputString = new String(result, 0, resultLength, "UTF-8");
 } catch (java.io.UnsupportedEncodingException ex) {
     // handle
 } catch (java.util.zip.DataFormatException ex) {
     // handle
 }
 

See also:

• Deflater

Summary

Public constructors
Inflater(boolean nowrap) Creates a new decompressor.
Inflater() Creates a new decompressor.

Public methods
void	end() Closes the decompressor and discards any unprocessed input.
boolean	finished() Returns true if the end of the compressed data stream has been reached.
int	getAdler() Returns the ADLER-32 value of the uncompressed data.
long	getBytesRead() Returns the total number of compressed bytes input so far.
long	getBytesWritten() Returns the total number of uncompressed bytes output so far.
int	getRemaining() Returns the total number of bytes remaining in the input buffer.
int	getTotalIn() Returns the total number of compressed bytes input so far.
int	getTotalOut() Returns the total number of uncompressed bytes output so far.
int	inflate(byte[] output) Uncompresses bytes into specified buffer.
int	inflate(ByteBuffer output) Uncompresses bytes into specified buffer.
int	inflate(byte[] output, int off, int len) Uncompresses bytes into specified buffer.
boolean	needsDictionary() Returns true if a preset dictionary is needed for decompression.
boolean	needsInput() Returns true if no data remains in the input buffer.
void	reset() Resets inflater so that a new set of input data can be processed.
void	setDictionary(ByteBuffer dictionary) Sets the preset dictionary to the bytes in the given buffer.
void	setDictionary(byte[] dictionary, int off, int len) Sets the preset dictionary to the given array of bytes.
void	setDictionary(byte[] dictionary) Sets the preset dictionary to the given array of bytes.
void	setInput(ByteBuffer input) Sets input data for decompression.
void	setInput(byte[] input, int off, int len) Sets input data for decompression.
void	setInput(byte[] input) Sets input data for decompression.

Inherited methods

From class java.lang.Object Object clone() Creates and returns a copy of this object. boolean equals(Object obj) Indicates whether some other object is "equal to" this one. void finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. final Class<?> getClass() Returns the runtime class of this Object. int hashCode() Returns a hash code value for the object. final void notify() Wakes up a single thread that is waiting on this object's monitor. final void notifyAll() Wakes up all threads that are waiting on this object's monitor. String toString() Returns a string representation of the object. final void wait(long timeoutMillis, int nanos) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait(long timeoutMillis) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait() Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

Public constructors

Inflater

Added in API level 1

public Inflater (boolean nowrap)

Creates a new decompressor. If the parameter 'nowrap' is true then the ZLIB header and checksum fields will not be used. This provides compatibility with the compression format used by both GZIP and PKZIP.

Note: When using the 'nowrap' option it is also necessary to provide an extra "dummy" byte as input. This is required by the ZLIB native library in order to support certain optimizations.

Parameters
nowrap	boolean: if true then support GZIP compatible compression

Inflater

Added in API level 1

public Inflater ()

Creates a new decompressor.

Public methods

end

Added in API level 1

public void end ()

Closes the decompressor and discards any unprocessed input. This method should be called when the decompressor is no longer being used. Once this method is called, the behavior of the Inflater object is undefined.

finished

Added in API level 1

public boolean finished ()

Returns true if the end of the compressed data stream has been reached.

Returns
boolean	true if the end of the compressed data stream has been reached

getAdler

Added in API level 1

public int getAdler ()

Returns the ADLER-32 value of the uncompressed data.

Returns
int	the ADLER-32 value of the uncompressed data

getBytesRead

Added in API level 1

public long getBytesRead ()

Returns the total number of compressed bytes input so far.

Returns
long	the total (non-negative) number of compressed bytes input so far

getBytesWritten

Added in API level 1

public long getBytesWritten ()

Returns the total number of uncompressed bytes output so far.

Returns
long	the total (non-negative) number of uncompressed bytes output so far

getRemaining

Added in API level 1

public int getRemaining ()

Returns the total number of bytes remaining in the input buffer. This can be used to find out what bytes still remain in the input buffer after decompression has finished.

Returns
int	the total number of bytes remaining in the input buffer

getTotalIn

Added in API level 1

public int getTotalIn ()

Returns the total number of compressed bytes input so far.

Since the number of bytes may be greater than Integer.MAX_VALUE, the getBytesRead() method is now the preferred means of obtaining this information.

Returns
int	the total number of compressed bytes input so far

getTotalOut

Added in API level 1

public int getTotalOut ()

Returns the total number of uncompressed bytes output so far.

Since the number of bytes may be greater than Integer.MAX_VALUE, the getBytesWritten() method is now the preferred means of obtaining this information.

Returns
int	the total number of uncompressed bytes output so far

inflate

Added in API level 1

public int inflate (byte[] output)

Uncompresses bytes into specified buffer. Returns actual number of bytes uncompressed. A return value of 0 indicates that needsInput() or needsDictionary() should be called in order to determine if more input data or a preset dictionary is required. In the latter case, getAdler() can be used to get the Adler-32 value of the dictionary required.

The remaining byte count will be reduced by the number of consumed input bytes. If the setInput(java.nio.ByteBuffer) method was called to provide a buffer for input, the input buffer's position will be advanced the number of consumed bytes.

These byte totals, as well as the total bytes read and the total bytes written values, will be updated even in the event that a DataFormatException is thrown to reflect the amount of data consumed and produced before the exception occurred.

Parameters
output	byte: the buffer for the uncompressed data

Returns
int	the actual number of uncompressed bytes

Throws
DataFormatException	if the compressed data format is invalid

See also:

• needsInput()
• needsDictionary()

inflate

Added in API level 35

public int inflate (ByteBuffer output)

Uncompresses bytes into specified buffer. Returns actual number of bytes uncompressed. A return value of 0 indicates that needsInput() or needsDictionary() should be called in order to determine if more input data or a preset dictionary is required. In the latter case, getAdler() can be used to get the Adler-32 value of the dictionary required.

On success, the position of the given output byte buffer will be advanced by as many bytes as were produced by the operation, which is equal to the number returned by this method. Note that the position of the output buffer will be advanced even in the event that a DataFormatException is thrown.

The remaining byte count will be reduced by the number of consumed input bytes. If the setInput(java.nio.ByteBuffer) method was called to provide a buffer for input, the input buffer's position will be advanced the number of consumed bytes.

These byte totals, as well as the total bytes read and the total bytes written values, will be updated even in the event that a DataFormatException is thrown to reflect the amount of data consumed and produced before the exception occurred.

Parameters
output	ByteBuffer: the buffer for the uncompressed data

Returns
int	the actual number of uncompressed bytes

Throws
DataFormatException	if the compressed data format is invalid
ReadOnlyBufferException	if the given output buffer is read-only

See also:

• needsInput()
• needsDictionary()

inflate

Added in API level 1

public int inflate (byte[] output, 
                int off, 
                int len)

Uncompresses bytes into specified buffer. Returns actual number of bytes uncompressed. A return value of 0 indicates that needsInput() or needsDictionary() should be called in order to determine if more input data or a preset dictionary is required. In the latter case, getAdler() can be used to get the Adler-32 value of the dictionary required.

If the setInput(java.nio.ByteBuffer) method was called to provide a buffer for input, the input buffer's position will be advanced by the number of bytes consumed by this operation, even in the event that a DataFormatException is thrown.

The remaining byte count will be reduced by the number of consumed input bytes. If the setInput(java.nio.ByteBuffer) method was called to provide a buffer for input, the input buffer's position will be advanced the number of consumed bytes.

These byte totals, as well as the total bytes read and the total bytes written values, will be updated even in the event that a DataFormatException is thrown to reflect the amount of data consumed and produced before the exception occurred.

Parameters
output	byte: the buffer for the uncompressed data
off	int: the start offset of the data
len	int: the maximum number of uncompressed bytes

Returns
int	the actual number of uncompressed bytes

Throws
DataFormatException	if the compressed data format is invalid

See also:

• needsInput()
• needsDictionary()

needsDictionary

Added in API level 1

public boolean needsDictionary ()

Returns true if a preset dictionary is needed for decompression.

Returns
boolean	true if a preset dictionary is needed for decompression

See also:

• setDictionary(byte)

needsInput

Added in API level 1

public boolean needsInput ()

Returns true if no data remains in the input buffer. This can be used to determine if one of the setInput() methods should be called in order to provide more input.

Returns
boolean	true if no data remains in the input buffer

reset

Added in API level 1

public void reset ()

Resets inflater so that a new set of input data can be processed.

setDictionary

Added in API level 35

public void setDictionary (ByteBuffer dictionary)

Sets the preset dictionary to the bytes in the given buffer. Should be called when inflate() returns 0 and needsDictionary() returns true indicating that a preset dictionary is required. The method getAdler() can be used to get the Adler-32 value of the dictionary needed.

The bytes in given byte buffer will be fully consumed by this method. On return, its position will equal its limit.

Parameters
dictionary	ByteBuffer: the dictionary data bytes

See also:

• needsDictionary()
• getAdler()

setDictionary

Added in API level 1

public void setDictionary (byte[] dictionary, 
                int off, 
                int len)

Sets the preset dictionary to the given array of bytes. Should be called when inflate() returns 0 and needsDictionary() returns true indicating that a preset dictionary is required. The method getAdler() can be used to get the Adler-32 value of the dictionary needed.

Parameters
dictionary	byte: the dictionary data bytes
off	int: the start offset of the data
len	int: the length of the data

See also:

• needsDictionary()
• getAdler()

setDictionary

Added in API level 1

public void setDictionary (byte[] dictionary)

Sets the preset dictionary to the given array of bytes. Should be called when inflate() returns 0 and needsDictionary() returns true indicating that a preset dictionary is required. The method getAdler() can be used to get the Adler-32 value of the dictionary needed.

Parameters
dictionary	byte: the dictionary data bytes

See also:

• needsDictionary()
• getAdler()

setInput

Added in API level 35

public void setInput (ByteBuffer input)

Sets input data for decompression.

One of the setInput() methods should be called whenever needsInput() returns true indicating that more input data is required.

The given buffer's position will be advanced as inflate operations are performed, up to the buffer's limit. The input buffer may be modified (refilled) between inflate operations; doing so is equivalent to creating a new buffer and setting it with this method.

Modifying the input buffer's contents, position, or limit concurrently with an inflate operation will result in undefined behavior, which may include incorrect operation results or operation failure.

Parameters
input	ByteBuffer: the input data bytes

See also:

• needsInput()

setInput

Added in API level 1

public void setInput (byte[] input, 
                int off, 
                int len)

Sets input data for decompression.

One of the setInput() methods should be called whenever needsInput() returns true indicating that more input data is required.

Parameters
input	byte: the input data bytes
off	int: the start offset of the input data
len	int: the length of the input data

See also:

• needsInput()

setInput

Added in API level 1

public void setInput (byte[] input)

Sets input data for decompression.

One of the setInput() methods should be called whenever needsInput() returns true indicating that more input data is required.

Parameters
input	byte: the input data bytes

See also:

• needsInput()