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–
