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Buffer isReadOnly() methods in Java with Examples

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  • Last Updated : 16 Jul, 2019
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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");
    }
}


Output:

buffer is ReadOnly buffer

Reference: https://docs.oracle.com/javase/9/docs/api/java/nio/Buffer.html#isReadOnly–


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