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DoubleBuffer asReadOnlyBuffer() method in Java with Examples
  • Last Updated : 04 Dec, 2018
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The asReadOnlyBuffer() method of java.nio.DoubleBuffer Class is used to create a new, read-only double buffer with this buffer’s content. The new buffer is a replica of this buffer. Hence changes made to this buffer’s content will be visible in the new buffer.

Since the new buffer is read-only, therefore any modification to its content won’t be allowed. The two buffers’ position, limit, and mark values will be independent. The new buffer’s capacity, limit, position, and mark values will be identical to those of this buffer. If this buffer is itself read-only then this method behaves in exactly the same way as the duplicate method.

Syntax:

public abstract DoubleBuffer asReadOnlyBuffer()

Return Value: This method returns the new, read-only double buffer with the same content as that of this buffer.

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



Example 1:




// Java program to demonstrate
// asReadOnlyBuffer() method
  
import java.nio.*;
import java.util.*;
  
public class GFG {
  
    public static void main(String[] args)
    {
  
        // Declaring the capacity of the DoubleBuffer
        int capacity = 10;
  
        // Creating the DoubleBuffer
        try {
  
            // creating object of floatbuffer
            // and allocating size capacity
            DoubleBuffer db = DoubleBuffer.allocate(capacity);
  
            // putting the value in floatbuffer
            db.put(8.56);
            db.put(2, 9.61);
            db.rewind();
  
            // print the DoubleBuffer
            System.out.println("Original DoubleBuffer: "
                               + Arrays.toString(db.array()));
  
            // Creating a read-only copy of DoubleBuffer
            // using asReadOnlyBuffer() method
            DoubleBuffer floatBuffer = db.asReadOnlyBuffer();
  
            // print the DoubleBuffer
            System.out.print("\nReadOnlyBuffer DoubleBuffer: ");
  
            while (floatBuffer.hasRemaining())
                System.out.print(floatBuffer.get() + ", ");
        }
  
        catch (IllegalArgumentException e) {
  
            System.out.println("IllegalArgumentException catched");
        }
  
        catch (ReadOnlyBufferException e) {
  
            System.out.println("ReadOnlyBufferException catched");
        }
    }
}
Output:
Original DoubleBuffer: [8.56, 0.0, 9.61, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]

ReadOnlyBuffer DoubleBuffer: 8.56, 0.0, 9.61, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,

Example 2:




// Java program to demonstrate
// asReadOnlyBuffer() method
  
import java.nio.*;
import java.util.*;
  
public class GFG {
  
    public static void main(String[] args) throws Exception
    {
  
        // Declaring the capacity of the db
        int capacity1 = 10;
  
        // Declaring the capacity of the db1
        int capacity2 = 5;
  
        // Creating the DoubleBuffer
        try {
  
            //
            // db
            //
            // creating object of Doublebuffer db
            // and allocating size capacity
            DoubleBuffer db = DoubleBuffer.allocate(capacity1);
  
            // putting the value in db
            db.put(8.56);
            db.put(2, 9.61);
            db.rewind();
  
            // print the DoubleBuffer
            System.out.println("DoubleBuffer db: "
                               + Arrays.toString(db.array()));
  
            //
            // db1
            //
            // creating object of Doublebuffer db1
            // and allocating size capacity
            DoubleBuffer db1 = DoubleBuffer.allocate(capacity2);
  
            // putting the value in db1
            db1.put(1, 4.56);
            db1.put(2, 6.45);
            db1.rewind();
  
            // print the DoubleBuffer
            System.out.println("\nDoubleBuffer db1: "
                               + Arrays.toString(db1.array()));
  
            // Creating a read-only copy of DoubleBuffer
            // using asReadOnlyBuffer() method
            DoubleBuffer readOnlyDb = db.asReadOnlyBuffer();
  
            // print the DoubleBuffer
            System.out.print("\nReadOnlyBuffer DoubleBuffer: ");
  
            while (readOnlyDb.hasRemaining())
                System.out.print(readOnlyDb.get() + ", ");
  
            // try to change readOnlyDb
            System.out.println("\n\nTrying to get the array"
                               + " from ReadOnlyDb for editing");
            Arrays.toString(readOnlyDb.array());
        }
        catch (IllegalArgumentException e) {
            System.out.println("IllegalArgumentException catched");
        }
        catch (ReadOnlyBufferException e) {
            System.out.println("Exception thrown: " + e);
        }
    }
}
Output:
DoubleBuffer db: [8.56, 0.0, 9.61, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]

DoubleBuffer db1: [0.0, 4.56, 6.45, 0.0, 0.0]

ReadOnlyBuffer DoubleBuffer: 8.56, 0.0, 9.61, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 

Trying to get the array from ReadOnlyDb for editing
Exception thrown: java.nio.ReadOnlyBufferException

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