CharBuffer flip() methods in Java with Examples

The flip() method of java.nio.CharBuffer Class is used to flip this buffer. The limit is set to the current position and then the position is set to zero. If the mark is defined then it is discarded. After a sequence of channel-read or put operations, invoke this method to prepare for a sequence of channel-write or relative get operations.

For example:

buf.put(magic); // Prepend header
in.read(buf); // Read data into rest of buffer
buf.flip(); // Flip buffer
out.write(buf); // Write header + data to channel



This method is often used in conjunction with the compact() method when transferring data from one place to another.

Syntax:

public final CharBuffer flip()

Return Value: This method returns this buffer.

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

Examples 1:

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// Java program to demonstrate
// flip() method
  
import java.nio.*;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // Declare and initialize the char array
        char[] cb = { 'a', 'b', 'c' };
  
        // wrap the char array into CharBuffer
        // using wrap() method
        CharBuffer charBuffe
            r
            = CharBuffer.wrap(cb);
  
        // set position at index 1
        charBuffer.position(1);
  
        // print the char buffer
        System.out.println("CharBuffer before flip: "
                           + Arrays.toString(
                                 charBuffer.array())
                           + "\nPosition: "
                           + charBuffer.position()
                           + "\nLimit: "
                           + charBuffer.limit());
  
        // Flip the charBuffer
        // using flip() method
        charBuffer.flip();
  
        // print the byte buffer
        System.out.println("\nCharBuffer after flip: "
                           + Arrays.toString(
                                 charBuffer.array())
                           + "\nPosition: "
                           + charBuffer.position()
                           + "\nLimit: "
                           + charBuffer.limit());
    }
}

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Output:

CharBuffer before flip: [a, b, c]
Position: 1
Limit: 3

CharBuffer after flip: [a, b, c]
Position: 0
Limit: 1

Examples 2:

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// Java program to demonstrate
// flip() method
  
import java.nio.*;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
    {
        // defining and allocating CharBuffer
        // using allocate() method
        CharBuffer charBuffer
            = CharBuffer.allocate(4);
  
        // append char value in charBuffer
        // using append() method
        charBuffer.append('a');
        charBuffer.append('b');
  
        // print the char buffer
        System.out.println("CharBuffer before flip: "
                           + Arrays.toString(
                                 charBuffer.array())
                           + "\nPosition: "
                           + charBuffer.position()
                           + "\nLimit: "
                           + charBuffer.limit());
  
        // Flip the charBuffer
        // using flip() method
        charBuffer.flip();
  
        // print the char buffer
        System.out.println("CharBuffer before flip: "
                           + Arrays.toString(
                                 charBuffer.array())
                           + "\nPosition: "
                           + charBuffer.position()
                           + "\nLimit: "
                           + charBuffer.limit());
    }
}

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Output:

CharBuffer before flip: [a, b, c,  ]
Position: 3
Limit: 4
CharBuffer before flip: [a, b, c,  ]
Position: 0
Limit: 3

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



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