CharBuffer clear() methods in Java with Examples

Last Updated : 23 Jul, 2019

The clear() method of java.nio.CharBuffer Class is used to clear this buffer. The position is set to zero, the limit is set to the capacity, and the mark is discarded. Invoke this method before using a sequence of channel-read or put operations to fill this buffer.

For example:

   // Prepare buffer for reading  buf.clear();    // Read data  in.read(buf);

This method does not actually erase the data in the buffer, but it is named as if it did because it will most often be used in situations in which that might as well be the case.

Syntax:

public final CharBuffer clear()

Return Value: This method returns this buffer.

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

Examples 1:

   // Java program to demonstrate 
// clear() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
  
    public static void main(String[] args) 
    { 
  
        try { 
  
            char[] carr = { 'a', 'b', 'c', 'd' }; 
  
            // creating object of CharBuffer 
            // and allocating size capacity 
            CharBuffer cb = CharBuffer.wrap(carr); 
  
            // try to set the position at index 2 
            cb.position(2); 
  
            // Set this buffer mark position 
            // using mark() method 
            cb.mark(); 
  
            // try to set the position at index 4 
            cb.position(4); 
  
            // display position 
            System.out.println("position before reset: "
                               + cb.position()); 
  
            // try to call clear() to restore 
            // to the position at index 0 
            // by discarding the mark 
            cb.clear(); 
  
            // display position 
            System.out.println("position after reset: "
                               + cb.position()); 
        } 
  
        catch (InvalidMarkException e) { 
            System.out.println("new position is less than "
                               + "the position we "
                               + "marked before "); 
            System.out.println("Exception throws: " + e); 
        } 
    } 
} 
 
  

Output:

  position before reset: 4  position after reset: 0

Examples 2:

   // Java program to demonstrate 
// clear() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
  
    public static void main(String[] args) 
    { 
  
        char[] carr = { '.', '<', '@', 'a' }; 
  
        // creating object of CharBuffer 
        // and allocating size capacity 
        CharBuffer cb = CharBuffer.wrap(carr); 
  
        // try to set the position at index 2 
        cb.position(3); 
  
        // display position 
        System.out.println("position before clear: "
                           + cb.position()); 
  
        // try to call clear() to restore 
        // to the position at index 0 
        // by discarding the mark 
        cb.clear(); 
  
        // display position 
        System.out.println("position after clear: "
                           + cb.position()); 
    } 
} 
 
  

Output:

  position before clear: 3  position after clear: 0

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

CharBuffer chars() methods in Java with Examples

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CharBuffer clear() methods in Java with Examples

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