FloatBuffer compact() method in Java With Examples

The compact() method of java.nio.FloatBuffer Class is used to compact the given buffer.

The values between the buffer’s current position and its limit are copied to the beginning of the buffer. The buffer’s position is then set to n+1 and its limit is set to its capacity. The buffer’s position is set to the number of floats copied.

Syntax :

public abstract FloatBuffer compact()

Return Value: This method returns the new FloatBuffer with the same content as that of this buffer.

Exception: This method throws the ReadOnlyBufferException, If this buffer is read-only.

Below program illustrates the compact() method:

Examples 1:

// Java program to demonstrate
// compact() method

import java.nio.*;
import java.util.*;

public class GFG {
    public static void main(String[] args)
    {

        // Declaring the capacity of the FloatBuffer
        int capacity = 10;

        // Creating the FloatBuffer

        // creating object of floatbuffer
        // and allocating size capacity
        FloatBuffer fb = FloatBuffer.allocate(capacity);

        // putting the value in floatbuffer
        fb.put(8.56F);
        fb.put(9.61F);
        fb.put(9.61F);

        // print the FloatBuffer
        System.out.println("Original FloatBuffer: "
                           + Arrays.toString(fb.array()));

        System.out.println("Position: " + fb.position());

        System.out.println("limit: " + fb.limit());

        // Creating a compacted  FloatBuffer of same FloatBuffer
        // using compact() method
        FloatBuffer floatBuffer = fb.compact();

        // print the FloatBuffer
        System.out.println("\nCompacted FloatBuffer: "
                           + Arrays.toString(floatBuffer.array()));

        System.out.println("Position: " + floatBuffer.position());

        System.out.println("limit: " + floatBuffer.limit());

        // putting the value in compacted floatbuffer
        floatBuffer.put(9.61F);

        // print the FloatBuffer
        System.out.println("\nUpdated Compacted FloatBuffer: "
                           + Arrays.toString(floatBuffer.array()));
        System.out.println("Position: " + floatBuffer.position());
        System.out.println("limit: " + floatBuffer.limit());
    }
}

Output:

Original FloatBuffer: [8.56, 9.61, 9.61, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
Position: 3
limit: 10

Compacted FloatBuffer: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
Position: 7
limit: 10

Updated Compacted FloatBuffer: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 9.61, 0.0, 0.0]
Position: 8
limit: 10

Examples 2:

// Java program to demonstrate
// compact() method

import java.nio.*;
import java.util.*;

public class GFG {
    public static void main(String[] args)
    {

        // Declaring the capacity of the FloatBuffer
        int capacity = 10;

        // Creating the FloatBuffer
        try {

            // creating object of FloatBuffer
            // and allocating size capacity
            FloatBuffer fb = FloatBuffer.allocate(capacity);

            // putting the value in floatbuffer
            fb.put(8.56F);
            fb.put(9.61F);
            fb.put(9.61F);
            fb.rewind();

            // Creating a read-only copy of FloatBuffer
            // using asReadOnlyBuffer() method
            FloatBuffer fb1 = fb.asReadOnlyBuffer();

            // print the ReadOnlyBuffer
            System.out.print("ReadOnlyBuffer FloatBuffer: ");
            while (fb1.hasRemaining())
                System.out.print(fb1.get() + ", ");
            System.out.println("");

            // print the Position of FloatBuffer fb
            System.out.println("\nPosition: " + fb.position());

            // print the Limit of FloatBuffer fb
            System.out.println("\nlimit: " + fb.limit());

            // Creating a compacted  FloatBuffer of same ReadOnlyBuffer
            // using compact() method
            System.out.println("\nTrying to compact the ReadOnlyBuffer fb1");
            FloatBuffer floatBuffer = fb1.compact();
        }

        catch (IllegalArgumentException e) {

            System.out.println("Exception throws " + e);
        }

        catch (ReadOnlyBufferException e) {

            System.out.println("Exception throws " + e);
        }
    }
}

Output:

ReadOnlyBuffer FloatBuffer: 8.56, 9.61, 9.61, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 

Position: 0

limit: 10

Trying to compact the ReadOnlyBuffer fb1
Exception throws java.nio.ReadOnlyBufferException