The arrayOffset() method of java.nio.LongBuffer 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().
In order 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 Long 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 illustrate the arrayOffset() method.
Program 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 LongBuffer        int capacity = 10;          // Creating the LongBuffer        try {              // creating object of Longbuffer            // and allocating size capacity            LongBuffer ib = LongBuffer.allocate(capacity);              // putting the value in Longbuffer            ib.put(8);            ib.put(2, 9);              // prLong the LongBuffer            System.out.println("LongBuffer: "                               + Arrays.toString(ib.array()));              // prLong the arrayOffset            System.out.println("arrayOffset: "                               + ib.arrayOffset());        }          catch (IllegalArgumentException e) {            System.out.println("IllegalArgumentException catched");        }          catch (ReadOnlyBufferException e) {            System.out.println("Exception throws" + e);        }    }} |
Output:
LongBuffer: [8, 0, 9, 0, 0, 0, 0, 0, 0, 0] arrayOffset: 0
Program 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 LongBuffer        int capacity = 10;          // Creating the LongBuffer        try {              // creating object of Longbuffer            // and allocating size capacity            LongBuffer ib = LongBuffer.allocate(capacity);              // putting the value in Longbuffer            ib.put(8);            ib.put(2, 9);            ib.rewind();              // Creating a read-only copy of LongBuffer            // using asReadOnlyBuffer() method            LongBuffer ib1 = ib.asReadOnlyBuffer();              // prLong the LongBuffer            System.out.print("Read only buffer : ");            while (ib1.hasRemaining())                System.out.print(ib1.get() + ", ");              // next line            System.out.println("");              // prLong the arrayOffset            System.out.println("\nTry to prLong the array offset"                               + " of read only buffer");            System.out.println("arrayOffset: " + ib1.arrayOffset());        }          catch (IllegalArgumentException e) {            System.out.println("Exception throws: " + e);        }          catch (ReadOnlyBufferException e) {            System.out.println("Exception throws: " + e);        }    }} |
Output:
Read only buffer : 8, 0, 9, 0, 0, 0, 0, 0, 0, 0, Try to prLong the array offset of read only buffer Exception throws: java.nio.ReadOnlyBufferException
