The arrayOffset() method of java.nio.CharBuffer 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.
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 CharBuffer
int capacity = 10 ;
// Creating the CharBuffer
try {
// creating object of CharBuffer
// and allocating size capacity
CharBuffer cb = CharBuffer.allocate(capacity);
// putting the value in CharBuffer
cb.put( 'a' );
cb.put( 2 , 'b' );
// print the CharBuffer
System.out.println( "CharBuffer: "
+ Arrays.toString(cb.array()));
// print the arrayOffset
System.out.println( "arrayOffset: "
+ cb.arrayOffset());
}
catch (IllegalArgumentException e) {
System.out.println( "IllegalArgumentException catched" );
}
catch (ReadOnlyBufferException e) {
System.out.println( "Exception throws" + e);
}
}
} |
CharBuffer: [a, , b, , , , , , , ] arrayOffset: 0
Example 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 CharBuffer
int capacity = 10 ;
// Creating the CharBuffer
try {
// creating object of CharBuffer
// and allocating size capacity
CharBuffer fb = CharBuffer.allocate(capacity);
// putting the value in CharBuffer
fb.put( 'a' );
fb.put( 2 , 'b' );
fb.rewind();
// Creating a read-only copy of CharBuffer
// using asReadOnlyBuffer() method
CharBuffer cb1 = fb.asReadOnlyBuffer();
// print the CharBuffer
System.out.print( "Read only buffer : " );
while (cb1.hasRemaining())
System.out.print(cb1.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: " + cb1.arrayOffset());
}
catch (IllegalArgumentException e) {
System.out.println( "Exception throws: " + e);
}
catch (ReadOnlyBufferException e) {
System.out.println( "Exception throws: " + e);
}
}
} |
Read only buffer : a, , b, , , , , , , , Try to print the array offset of read only buffer Exception throws: java.nio.ReadOnlyBufferException