What is the floatBuffer rewind() method in Java?

java.nio.FloatBuffer is a class we can use to store a buffer of floats. We can use this class’s rewind() method to rewind a buffer. Rewinding a buffer sets the buffer position to zero.

  • Limit of the buffer remains unaffected.
  • Any position previously marked is discarded.

Declaration

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

buff.rewind()
  • buff: The FloatBuffer to rewind.

Return value

The FloatBuffer.rewind() method returns the FloatBuffer buff after rewinding.

Code

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

import java.nio.*;
import java.util.*;
public class main {
   public static void main(String[] args) {
      int n1 = 4;
      int n2 = 4;
      try {
         FloatBuffer buff1 = FloatBuffer.allocate(n1);
         buff1.put(1.5F);
         buff1.put(4.6F);
         System.out.println("buff1: " + Arrays.toString(buff1.array()));
         System.out.println("position at(before rewind): " + buff1.position());
         System.out.println("rewind()");
         buff1.rewind();
         System.out.println("position at(after rewind): " + buff1.position());
         buff1.put(1.9F);
         System.out.println("buff1: " + Arrays.toString(buff1.array()));
         
      } catch (IllegalArgumentException e) {
         System.out.println("Error!!! IllegalArgumentException");
      } catch (ReadOnlyBufferException e) {
         System.out.println("Error!!! ReadOnlyBufferException");
      }
   }
}

Explanation

  • A FloatBuffer buff1 is declared in line 8.
  • Two elements are added to buff1 using the put() method in lines 9-10. 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 rewind is 2. After calling the rewind() method in line 16, the position of buff1 is set to 0. This is why calling the put() method on buff1 adds the element at the 0th index of buff1.

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