The arrayOffset() method of java.nio.DoubleBuffer class is used to return the offset within the buffer’s backing array of the first element of the buffer. It means that if this buffer is backed by an array, then buffer position p corresponds to array index p + arrayOffset().
Inorder to check whether this buffer has a backing array, hasArray() method can be used. It ensures that this buffer has an accessible backing array.
Syntax:
public final int arrayOffset()
Return Value: This method returns the offset within this buffer’s array of the first element of the buffer.
Exception: This method throws ReadOnlyBufferException if this buffer is backed by an array but is read-only
Below program illustrates the arrayOffset() method.
Examples 1:
// Java program to demonstrate// arrayOffset() 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);              // print the DoubleBuffer            System.out.println("DoubleBuffer: "                               + Arrays.toString(fb.array()));              // print the arrayOffset            System.out.println("arrayOffset: "                               + fb.arrayOffset());        }          catch (IllegalArgumentException e) {            System.out.println("IllegalArgumentException catched");        }          catch (ReadOnlyBufferException e) {            System.out.println("Exception throws" + e);        }    }} |
Output:
DoubleBuffer: [8.5600004196167, 0.0, 9.609999656677246, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0] arrayOffset: 0
Examples 2: To demonstrate ReadOnlyBufferException
// Java program to demonstrate// arrayOffset() 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();              // print the DoubleBuffer            System.out.print("Read only buffer : ");            while (fb1.hasRemaining())                System.out.print(fb1.get() + ", ");              // next line            System.out.println("");              // print the arrayOffset            System.out.println("\nTry to print the array offset"                               + " of read only buffer");            System.out.println("arrayOffset: " + fb1.arrayOffset());        }          catch (IllegalArgumentException e) {            System.out.println("Exception throws: " + e);        }          catch (ReadOnlyBufferException e) {            System.out.println("Exception throws: " + e);        }    }} |
Output:
Read only buffer : 8.5600004196167, 0.0, 9.609999656677246, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, Try to print the array offset of read only buffer Exception throws: java.nio.ReadOnlyBufferException
