Inflater (Java SE 9 & JDK 9 )
Keywords: java.util.zip.Inflater class

Module java.base
Package java.util.zip

## Class Inflater

- java.lang.Object
- - java.util.zip.Inflater

-     public class Inflater
      extends Object

  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
  >      }

  Since:
    1.1
  See Also:
    `Deflater`

- - ### Constructor Summary

    Constructors
    Constructor | Description
    --- | ---
    `Inflater​()` | Creates a new decompressor.
    `Inflater​(boolean nowrap)` | Creates a new decompressor.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods Deprecated Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `void` | `end​()` | Closes the decompressor and discards any unprocessed input.
    `protected void` | `finalize​()` | Deprecated. The `finalize` method has been deprecated. Subclasses that override `finalize` in order to perform cleanup should be modified to use alternative cleanup mechanisms and to remove the overriding `finalize` method. When overriding the `finalize` method, its implementation must explicitly ensure that `super.finalize()` is invoked as described in `Object.finalize()`. See the specification for `Object.finalize()` for further information about migration options.
    `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)` | Sets the preset dictionary to the given array of bytes.
    `void` | `setDictionary​(byte[] b, int off, int len)` | Sets the preset dictionary to the given array of bytes.
    `void` | `setInput​(byte[] b)` | Sets input data for decompression.
    `void` | `setInput​(byte[] b, int off, int len)` | Sets input data for decompression.

    - ### Methods inherited from class java.lang.Object

      `clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### Inflater

          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` - if true then support GZIP compatible compression

    - #### Inflater

          public Inflater​()

      Creates a new decompressor.

  - ### Method Detail

    - #### setInput

          public 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` - the input data bytes
        `off` - the start offset of the input data
        `len` - the length of the input data
      See Also:
        `needsInput()`

    - #### setInput

          public 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` - the input data bytes
      See Also:
        `needsInput()`

    - #### setDictionary

          public 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` - the dictionary data bytes
        `off` - the start offset of the data
        `len` - the length of the data
      See Also:
        `needsDictionary()`, `getAdler()`

    - #### setDictionary

          public 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` - the dictionary data bytes
      See Also:
        `needsDictionary()`, `getAdler()`

    - #### getRemaining

          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:
        the total number of bytes remaining in the input buffer

    - #### needsInput

          public 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:
        true if no data remains in the input buffer

    - #### needsDictionary

          public boolean needsDictionary​()

      Returns true if a preset dictionary is needed for decompression.
      Returns:
        true if a preset dictionary is needed for decompression
      See Also:
        `setDictionary(byte[], int, int)`

    - #### finished

          public boolean finished​()

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

    - #### inflate

          public int inflate​(byte[] b,
                             int off,
                             int len)
                      throws DataFormatException

      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` - the buffer for the uncompressed data
        `off` - the start offset of the data
        `len` - the maximum number of uncompressed bytes
      Returns:
        the actual number of uncompressed bytes
      Throws:
        `DataFormatException` - if the compressed data format is invalid
      See Also:
        `needsInput()`, `needsDictionary()`

    - #### inflate

          public int inflate​(byte[] b)
                      throws DataFormatException

      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` - the buffer for the uncompressed data
      Returns:
        the actual number of uncompressed bytes
      Throws:
        `DataFormatException` - if the compressed data format is invalid
      See Also:
        `needsInput()`, `needsDictionary()`

    - #### getAdler

          public int getAdler​()

      Returns the ADLER-32 value of the uncompressed data.
      Returns:
        the ADLER-32 value of the uncompressed data

    - #### getTotalIn

          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:
        the total number of compressed bytes input so far

    - #### getBytesRead

          public long getBytesRead​()

      Returns the total number of compressed bytes input so far.
      Returns:
        the total (non-negative) number of compressed bytes input so far
      Since:
        1.5

    - #### getTotalOut

          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:
        the total number of uncompressed bytes output so far

    - #### getBytesWritten

          public long getBytesWritten​()

      Returns the total number of uncompressed bytes output so far.
      Returns:
        the total (non-negative) number of uncompressed bytes output so far
      Since:
        1.5

    - #### reset

          public void reset​()

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

    - #### end

          public 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.

    - #### finalize

          @Deprecated(since="9")
          protected void finalize​()

      Deprecated. The `finalize` method has been deprecated. Subclasses that override `finalize` in order to perform cleanup should be modified to use alternative cleanup mechanisms and to remove the overriding `finalize` method. When overriding the `finalize` method, its implementation must explicitly ensure that `super.finalize()` is invoked as described in `Object.finalize()`. See the specification for `Object.finalize()` for further information about migration options.
      Closes the decompressor when garbage is collected.
      Overrides:
        `finalize` in class `Object`
      See Also:
        `WeakReference`, `PhantomReference`