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LongBuffer arrayOffset() method in Java

  • Last Updated : 19 Sep, 2018

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.

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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



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