java.util.zip.Inflater.read() Method Example

Description

The java.util.zip.InflaterInputStream.read(byte[] buf, int off, int len) method reads uncompressed data into an array of bytes. If len is not zero, the method will block until some input can be decompressed; otherwise, no bytes are read and 0 is returned.

Declaration

Following is the declaration for java.util.zip.InflaterInputStream.read(byte[] buf, int off, int len) method.

public int read(byte[] buf, int off, int len)
   throws IOException

Parameters

• buf − the buffer into which the data is read.

• off − the start offset in the destination array b.

• len − the maximum number of bytes read.

Returns

the actual number of bytes read, or -1 if the end of the compressed input is reached or a preset dictionary is needed.

Exceptions

• NullPointerException − If buf is null.

• IndexOutOfBoundsException − If off is negative, len is negative, or len is greater than buf.length - off.

• ZipException − if a ZIP format error has occurred.

• IOException − if an I/O error has occurred.

Example

The following example shows the usage of java.util.zip.InflaterInputStream.read(byte[] buf, int off, int len) method.

package com.tutorialspoint;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.zip.DataFormatException;
import java.util.zip.Deflater;
import java.util.zip.InflaterInputStream;

public class InflaterInputStreamDemo {
   public static void main(String[] args) throws DataFormatException, IOException {
      String message = "Welcome to TutorialsPoint.com;"
         +"Welcome to TutorialsPoint.com;"
         +"Welcome to TutorialsPoint.com;"
         +"Welcome to TutorialsPoint.com;"
         +"Welcome to TutorialsPoint.com;"
         +"Welcome to TutorialsPoint.com;"
         +"Welcome to TutorialsPoint.com;"
         +"Welcome to TutorialsPoint.com;"
         +"Welcome to TutorialsPoint.com;"
         +"Welcome to TutorialsPoint.com;";
      System.out.println("Original Message length : " + message.length());
      byte[] input = message.getBytes("UTF-8");
      int length = message.length();
      // Compress the bytes
      byte[] output = new byte[1024];
      Deflater deflater = new Deflater();
      deflater.setInput(input);
   
      deflater.finish();
      int compressedDataLength = deflater.deflate(output,0 , output.length, Deflater.NO_FLUSH);
      System.out.println("Total uncompressed bytes input :" + deflater.getTotalIn());
      System.out.println("Compressed Message Checksum :" + deflater.getAdler());     
      deflater.finished();

      System.out.println("Compressed Message length : " + compressedDataLength);
   
      ByteArrayInputStream bin = new ByteArrayInputStream(output);
      InflaterInputStream inflaterInputStream = new InflaterInputStream(bin);
      byte[] result = new byte[1024];

      inflaterInputStream.read(result, 0, result.length);

      inflaterInputStream.close();
      // Decode the bytes into a String
      String message1 = new String(result,0, length,"UTF-8");
      System.out.println(message.equals(message1));
   }
}

Let us compile and run the above program, this will produce the following result −

Original Message length : 300
Total uncompressed bytes input :300
Compressed Message Checksum :368538129
Compressed Message length : 42
true