DoubleBuffer hasArray() method in Java with Examples

The hasArray() method of java.nio.DoubleBuffer class is used to ensure whether or not the given buffer is backed by an accessible float array. It returns true if there is an accessible backing array to this buffer, else it returns false. If this method returns true, then the array() and arrayOffset() methods may safely be invoked, as they work on the backing array.

Syntax:

public final boolean hasArray()

Returns: This method will return true if, and only if, this buffer is backed by an array and is not read-only. Else it returns false.

Below are the examples to illustrate the hasArray() method:

Examples 1: When the buffer is backed by an array

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

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

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

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

        // Creating the DoubleBuffer
        try {

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

            // putting the value in Doublebuffer
            fb.put(8.56F);
            fb.put(2, 9.61F);
            fb.rewind();

            // checking DoubleBuffer fb is backed by array or not
            boolean isArray = fb.hasArray();

            // checking if else condition
            if (isArray)
                System.out.println("DoubleBuffer fb is"
                                   + " backed by array");
            else
                System.out.println("DoubleBuffer fb is"
                                   + " not backed by any array");
        }

        catch (IllegalArgumentException e) {
            System.out.println("IllegalArgumentException catched");
        }

        catch (ReadOnlyBufferException e) {
            System.out.println("ReadOnlyBufferException catched");
        }
    }
}

Output:

DoubleBuffer fb is backed by array

Examples 2: When the buffer is backed by an array

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

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

public class GFG {

    public static void main(String[] args)
    {

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

        // Creating the DoubleBuffer
        try {

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

            // putting the value in Doublebuffer
            fb.put(8.56F);
            fb.put(2, 9.61F);
            fb.rewind();

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

            // checking DoubleBuffer fb is backed by array or not
            boolean isArray = fb1.hasArray();

            // checking if else condition
            if (isArray)
                System.out.println("DoubleBuffer fb is"
                                   + " backed by array");
            else
                System.out.println("DoubleBuffer fb is"
                                   + " not backed by any array");
        }

        catch (IllegalArgumentException e) {
            System.out.println("IllegalArgumentException catched");
        }

        catch (ReadOnlyBufferException e) {
            System.out.println("ReadOnlyBufferException catched");
        }
    }
}

Output:

DoubleBuffer fb is not backed by any array