What is the FloatBuffer clear() method in Java?

java.nio.FloatBuffer is a class we can use to store a buffer of floats. We can use the clear() method of this class to clear a buffer. Clearing a buffer means:

  • We set the buffer position to 0. Capacity is the number of elements a buffer contains. The limit of a buffer is its first index that should not be read or written. The limit of a buffer should be less than or equal to its capacity.
  • We set the buffer limit to the buffer capacity.
  • We discard the mark. Marking a position means recording a position that can be restored by the FloatBuffer.reset() method. This marked position is discarded by the FloatBuffer.reset() method.

Declaration

The FloatBuffer.clear() method is declared as follows:

buff.clear()
  • buff: The FloatBuffer to be cleared.

Return value

The FloatBuffer.clear() method returns the FloatBuffer buff after cleaning it.

Code

Consider the code snippet below, which demonstrates the use of the FloatBuffer.clear() method.

import java.nio.*;
import java.util.*;
public class main {
   public static void main(String[] args) {
      int n1 = 4;
      FloatBuffer buff1 = FloatBuffer.allocate(n1);
      buff1.put(1.7F);
      buff1.put(4.9F);
      buff1.limit(3);
      buff1.mark();
      System.out.println("buff1: " + Arrays.toString(buff1.array()));
      System.out.println("position at(before clear): " + buff1.position());
      System.out.println("Limit at(before clear): " + buff1.limit());
      buff1.mark();
      System.out.println("clear()");
      buff1.clear();
      System.out.println("position at(after rewind): " + buff1.position());
      System.out.println("Limit at(before clear): " + buff1.limit());
        
   }
}

Explanation

  • A FloatBuffer buff1 is declared in line 7 with the capacity n1 = 4.
  • Two elements are added to buff1 using the put() method in lines 8-9. After adding the first element, the position of buff1 is incremented from 0 to 1. After adding the second element, the position of buff1 is incremented from 1 to 2.
  • The position of buff1 before clear is 2. After calling the clear() method in line 21, the position of buff1 is set to 0.
  • The limit of buff1 is set to 3 using the limit() method in line 11. The limit of buff1 before clear() is 3. After calling the clear() method in line 21, the limit of buff1 is set to its capacity, which is 4.
  • The position of buff1 is marked to 2 using the mark() method in line 12. After calling the clear() method in line 21, the mark of buff1 is discarded and the position is set to 0.

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