Deflater setInput() function in Java with examples

The setInput() function of the Deflater class in java.util.zip is used to set input data for compression. This function should be called when needsInput() returns true indicating input buffer is empty.

Function Signature:

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

Syntax:

d.setInput(byte[]);
d.setInput(byte[], int, int);

Parameter: The various parameters accepted by these overloaded functions are:

• byte[] b: This is the input array that is to be deflated
• int offset: This is the starting offset from which the values are to be read in the given array
• int length: This is the maximum length to be compressed from the starting offset.

Return Type: The function has do not return anything.

Exception: The function does not throw any exception

Example 1:

// Java program to describe the use
// of setInput(byte[] b) function

import java.util.zip.*;
import java.io.UnsupportedEncodingException;

class GFG {
    public static void main(String args[])
        throws UnsupportedEncodingException
    {
        // deflater
        Deflater d = new Deflater();

        // get the text
        String pattern = "GeeksforGeeks", text = "";

        // generate the text
        for (int i = 0; i < 4; i++)
            text += pattern;

        // set the Input for deflator
        d.setInput(text.getBytes("UTF-8"));

        // finish
        d.finish();

        // output bytes
        byte output[] = new byte[1024];

        // compress the data
        int size = d.deflate(output);

        // compressed String
        System.out.println("Compressed String :"
                           + new String(output)
                           + "\n Size " + size);

        // original String
        System.out.println("Original String :" + text
                           + "\n Size " + text.length());

        // end
        d.end();
    }
}

Output:

Compressed String :x?sOM?.N?/r???q??
 Size 21
Original String :GeeksforGeeksGeeksforGeeksGeeksforGeeksGeeksforGeeks
 Size 52

Example 2:

// Java program to describe the use
// of setInput(byte[] b, int offset, int len) function

import java.util.zip.*;
import java.io.UnsupportedEncodingException;

class GFG {
    public static void main(String args[])
        throws UnsupportedEncodingException
    {
        // deflater
        Deflater d = new Deflater();

        // get the text
        String pattern = "GeeksforGeeks", text = "";

        // generate the text
        for (int i = 0; i < 4; i++)
            text += pattern;

        // set the Input for deflator
        d.setInput(text.getBytes("UTF-8"), 10, 30);

        // finish
        d.finish();

        // output bytes
        byte output[] = new byte[1024];

        // compress the data
        int size = d.deflate(output);

        // compressed String
        System.out.println("Compressed String :"
                           + new String(output)
                           + "\n Size " + size);

        // end
        d.end();
    }
}

Output:

Compressed String :x?K?.vOM?.N?/????
 Size 22

Reference: https://docs.oracle.com/javase/7/docs/api/java/util/zip/Deflater.html#setInput()