java.util.zip.Deflater.setInput() Method Example

Description

The java.util.zip.Deflater.setInput(byte[] b, int off, int len) method sets input data for compression. This should be called whenever needsInput() returns true indicating that more input data is required.

Declaration

Following is the declaration for java.util.zip.Deflater.setInput(byte[] b, int off, int len) method.

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

Parameters

• b − the input data bytes.

• off − he start offset of the data.

• len − the length of the data.

Example

The following example shows the usage of java.util.zip.Deflater.setInput(byte[] b, int off, int len) method.

package com.tutorialspoint;

import java.io.UnsupportedEncodingException;
import java.util.zip.DataFormatException;
import java.util.zip.Deflater;
import java.util.zip.Inflater;

public class DeflaterDemo {
   public static void main(String[] args) 
      throws DataFormatException, UnsupportedEncodingException {
      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");
      // Compress the bytes
      byte[] output = new byte[1024];

      Deflater deflater = new Deflater();
      int inCount = input.length;  
      int inPosition = 0;
      int outPosition = 0;

      int MAX_BUFFER_SIZE = 10;
      while(!deflater.finished()){
         int want = -1;
         int got;
         if (deflater.needsInput() && inCount != 0) {
            want = (inCount < MAX_BUFFER_SIZE) ? inCount : MAX_BUFFER_SIZE;

            deflater.setInput(input, inPosition, want);

            inCount -= want;
            inPosition += want;
            if (inCount == 0) {
               deflater.finish();
            }
         }
         // deflate to current position in output buffer
         int compCount;

         compCount = deflater.deflate(output, outPosition, MAX_BUFFER_SIZE);
         outPosition += compCount;
      }

      System.out.println("Total uncompressed bytes output :" + deflater.getTotalOut());     
      System.out.println("Compressed Message Checksum :" + deflater.getAdler());     
      deflater.finished();

      System.out.println("Compressed Message length : " + outPosition);

      // Decompress the bytes
      Inflater inflater = new Inflater();
      inflater.setInput(output, 0, outPosition);
      byte[] result = new byte[1024];
      int resultLength = inflater.inflate(result);
      inflater.finished();

      // Decode the bytes into a String
      message = new String(result, 0, resultLength, "UTF-8");
      System.out.println("UnCompressed Message Checksum :" + inflater.getAdler());  
      System.out.println("UnCompressed Message length : " + message.length());
   }
}

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

Original Message length : 300
Total uncompressed bytes output :42
Compressed Message Checksum :368538129
Compressed Message length : 42
UnCompressed Message Checksum :368538129
UnCompressed Message length : 300