Buffer isReadOnly() methods in Java with Examples

Last Updated : 16 Jul, 2019

The isReadOnly() method of java.nio.Buffer class is used to tell whether or not this buffer is read-only.

Syntax:

public abstract boolean isReadOnly()

Returns: This method will return true if, and only if, this buffer is read-only.

Below are the examples to illustrate the isReadOnly() method:

Examples 1:

// Java program to demonstrate 
// isReadOnly() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
  
        // Declaring the capacity of the ByteBuffer 
        int capacity = 10; 
  
        // creating object of bytebuffer 
        // and allocating size capacity 
        ByteBuffer bb = ByteBuffer.allocate(capacity); 
  
        // putting the value in bytebuffer 
        bb.put((byte)10); 
        bb.put((byte)20); 
        bb.rewind(); 
  
        // Typecast bytebuffer to Buffer 
        Buffer buffer = (Buffer)bb; 
  
        // checking buffer is backed by array or not 
        boolean isReadOnly = buffer.isReadOnly(); 
  
        // checking if else condition 
        if (isReadOnly) 
            System.out.println("buffer is"
                               + " ReadOnly buffer"); 
        else
            System.out.println("buffer is not"
                               + " ReadOnly buffer"); 
    } 
} 

Output:

buffer is not ReadOnly buffer

Examples 2:

// Java program to demonstrate 
// isReadOnly() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
  
        // Declaring the capacity of the ByteBuffer 
        int capacity = 10; 
  
        // creating object of bytebuffer 
        // and allocating size capacity 
        ByteBuffer bb = ByteBuffer.allocate(capacity); 
  
        // putting the value in bytebuffer 
        bb.put((byte)10); 
        bb.put((byte)20); 
        bb.rewind(); 
  
        // Creating a read-only copy of ByteBuffer 
        // using asReadOnlyBuffer() method 
        ByteBuffer bb1 = bb.asReadOnlyBuffer(); 
  
        // Typecast read-only ByteBuffer to read-only buffer 
        Buffer buffer = (Buffer)bb1; 
  
        // checking buffer is backed by array or not 
        boolean isReadOnly = buffer.isReadOnly(); 
  
        // checking if else condition 
        if (isReadOnly) 
            System.out.println("buffer is"
                               + " ReadOnly buffer"); 
        else
            System.out.println("buffer is not"
                               + " ReadOnly buffer"); 
    } 
} 