Skip to content

Most visited

Recently visited

navigation
Added in API level 1

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.

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€€";
     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:

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[] b)

Uncompresses bytes into specified buffer.

int inflate(byte[] b, 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(byte[] b, int off, int len)

Sets the preset dictionary to the given array of bytes.

void setDictionary(byte[] b)

Sets the preset dictionary to the given array of bytes.

void setInput(byte[] b, int off, int len)

Sets input data for decompression.

void setInput(byte[] b)

Sets input data for decompression.

Protected methods

void finalize()

Closes the decompressor when garbage is collected.

Inherited methods

From class java.lang.Object

Public constructors

Inflater

Added in API level 1
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
Inflater ()

Creates a new decompressor.

Public methods

end

Added in API level 1
void end ()

Closes the decompressor and discards any unprocessed input. This method should be called when the decompressor is no longer being used, but will also be called automatically by the finalize() method. Once this method is called, the behavior of the Inflater object is undefined.

finished

Added in API level 1
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
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
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
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
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
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
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
int inflate (byte[] b)

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.

Parameters
b 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:

inflate

Added in API level 1
int inflate (byte[] b, 
                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.

Parameters
b 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:

needsDictionary

Added in API level 1
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:

needsInput

Added in API level 1
boolean needsInput ()

Returns true if no data remains in the input buffer. This can be used to determine if #setInput 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
void reset ()

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

setDictionary

Added in API level 1
void setDictionary (byte[] b, 
                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
b byte: the dictionary data bytes
off int: the start offset of the data
len int: the length of the data

See also:

setDictionary

Added in API level 1
void setDictionary (byte[] b)

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
b byte: the dictionary data bytes

See also:

setInput

Added in API level 1
void setInput (byte[] b, 
                int off, 
                int len)

Sets input data for decompression. Should be called whenever needsInput() returns true indicating that more input data is required.

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

See also:

setInput

Added in API level 1
void setInput (byte[] b)

Sets input data for decompression. Should be called whenever needsInput() returns true indicating that more input data is required.

Parameters
b byte: the input data bytes

See also:

Protected methods

finalize

Added in API level 1
void finalize ()

Closes the decompressor when garbage is collected.

This site uses cookies to store your preferences for site-specific language and display options.

Hooray!

This class requires API level or higher

This doc is hidden because your selected API level for the documentation is . You can change the documentation API level with the selector above the left navigation.

For more information about specifying the API level your app requires, read Supporting Different Platform Versions.