Java.util.zip.DeflaterInputStream class in Java

Implements an input stream filter for compressing data in the “deflate” compression format.

Constructor and Description

• DeflaterInputStream(InputStream in) : Creates a new input stream with a default compressor and buffer size.
• DeflaterInputStream(InputStream in, Deflater defl) : Creates a new input stream with the specified compressor and a default buffer size.
• DeflaterInputStream(InputStream in, Deflater defl, int bufLen) :Creates a new input stream with the specified compressor and buffer size.

Methods:

• int available() : Returns 0 after EOF has been reached, otherwise always return 1.

  Syntax :public int available()
                throws IOException
  Parameters:
  n - number of bytes to be skipped
  Returns:
  the actual number of bytes skipped
  Throws:
  IOException

• void close() : Closes this input stream and its underlying input stream, discarding any pending uncompressed data.

  Syntax :public void close()
             throws IOException
  Overrides:
  close in class FilterInputStream
  Throws:
  IOException

• void mark(int limit) : This operation is not supported.

  Syntax :public void mark(int limit)
  Parameters:
  limit - maximum bytes that can be read before invalidating the position marker
  

• boolean markSupported() : Always returns false because this input stream does not support the mark() and reset() methods.

  Syntax :public boolean markSupported()
  Returns:
  false, always

• int read() : Reads a single byte of compressed data from the input stream.

  Syntax :public int read()
           throws IOException
  Returns:
  a single byte of compressed data, or -1 if the end of the uncompressed
  input stream is reached
  Throws:
  IOException

• int read(byte[] b, int off, int len) : Reads compressed data into a byte array.

  Syntax :public int read(byte[] b,
         int off,
         int len)
           throws IOException
  Parameters:
  b - buffer into which the data is read
  off - starting offset of the data within b
  len - maximum number of compressed bytes to read into b
  Returns:
  the actual number of bytes read, or -1 if the end of the
  uncompressed input stream is reached
  Throws:
  IndexOutOfBoundsException 
  IOException 

• void reset() : This operation is not supported.

  Syntax :public void reset()
             throws IOException
  Throws:
  IOException

• long skip(long n) : Skips over and discards data from the input stream.

  Syntax :public long skip(long n)
            throws IOException
  Parameters:
  n - number of bytes to be skipped
  Returns:
  the actual number of bytes skipped
  Throws:
  IOException

Program:

//Java program to illustrate DeflaterInputStream class
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.zip.DeflaterInputStream;

class DeflaterInputStreamDemo
{
    public static void main(String[] args) throws IOException
    {
        byte b[] = new byte[10];
        for (byte i = 0; i <10 ; i++)
        {
            b[i] = i;
        }
        ByteArrayInputStream bin = new ByteArrayInputStream(b);
        DeflaterInputStream din = new DeflaterInputStream(bin);

        //illustrating markSupported() method
        System.out.println(din.markSupported());

        //illustrating skip() method
        din.skip(1);

        //illustrating available() method
        System.out.println(din.available());

        //illustrating read(byte[] b,int off,int len)
        byte c[] = new byte[10];

        din.read(c,0,9);
                for (int i = 0; i < 9; i++)
        {
            System.out.print(c[i]);
        }
        while(din.available() == 1)
        {
            //Reads a single byte of compressed data
            System.out.print(din.read());
        }

        System.out.println();
        System.out.println(din.available());

        // illustrating close() method
        din.close();
    }
}

Output :

false
1
-1009996100981029710199231224400175046-1
0

The above output represents compressed data.

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