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–
