The arrayOffset() method of java.nio.ByteBuffer class is used to return the offset within the given buffer’s backing array of the first element of the buffer.
If this buffer is backed by an array then buffer position p corresponds to array index p + arrayOffset().
Invoke the hasArray method before invoking this method in order to ensure 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 the ReadOnlyBufferException, If this buffer is backed by an array but is read-only.
Below are the examples to illustrate the arrayOffset() method:
Example 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 ByteBuffer int capacity = 4; // Creating the ByteBuffer try { // creating object of ByteBuffer // and allocating size capacity ByteBuffer bb = ByteBuffer.allocate(capacity); // putting the int to byte typecast value in ByteBuffer bb.put((byte)20); bb.put((byte)30); bb.put((byte)40); bb.put((byte)50); bb.rewind(); // print the ByteBuffer System.out.println("ByteBuffer: " + Arrays.toString(bb.array())); // print the arrayOffset System.out.println("arrayOffset: " + bb.arrayOffset()); } catch (IllegalArgumentException e) { System.out.println("IllegalArgumentException catched"); } catch (ReadOnlyBufferException e) { System.out.println("Exception throws" + e); } }} |
Output:
ByteBuffer: [20, 30, 40, 50] arrayOffset: 0
Example 2:
// 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 ByteBuffer int capacity = 3; // Creating the ByteBuffer try { // creating object of ByteBuffer // and allocating size capacity ByteBuffer bb = ByteBuffer.allocate(capacity); // putting the value in ByteBuffer bb.put((byte)20); bb.put((byte)30); bb.put((byte)40); bb.rewind(); // Creating a read-only copy of ByteBuffer // using asReadOnlyBuffer() method ByteBuffer bb1 = bb.asReadOnlyBuffer(); // print the ByteBuffer System.out.print("Read only buffer : "); while (bb1.hasRemaining()) System.out.print(bb1.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: " + bb1.arrayOffset()); } catch (IllegalArgumentException e) { System.out.println("Exception throws: " + e); } catch (ReadOnlyBufferException e) { System.out.println("Exception throws: " + e); } }} |
Output:
Read only buffer : 20, 30, 40, Try to print the array offset of read only buffer Exception throws: java.nio.ReadOnlyBufferException
