Bitwise right shift operator in Java

Java supports two type of right shift operator. The>> operator is a signed right shift operator and >>> is an unsigned right shift operator. The left operands value is moved right by the number of bits specified by the right operand.

Signed right shift operator

The signed right shift operator '>>' uses the sign bit to fill the trailing positions. For example, if the number is positive then 0 will be used to fill the trailing positions and if the number is negative then 1 will be used to fill the trailing positions.

Assume if a = 60 and b = -60; now in binary format, they will be as follows −

a = 0000 0000 0000 0000 0000 0000 0011 1100
b = 1111 1111 1111 1111 1111 1111 1100 0100

In Java, negative numbers are stored as 2's complement.

Thus a >> 1 = 0000 0000 0000 0000 0000 0000 0001 1110
And b >> 1 = 1111 1111 1111 1111 1111 1111 1110 0010

Unsigned right shift operator

The unsigned right shift operator '>>' do not use the sign bit to fill the trailing positions. It always fills the trailing positions by 0s.

Thus a >>> 1 = 0000 0000 0000 0000 0000 0000 0001 1110
And b >>>  1 = 0111 1111 1111 1111 1111 1111 1110 0010

Example

Live Demo

public class Tester {
   public static void main(String[] args) {
      int a = 60;          int b = -60;        int c = 0;
      System.out.println("60  = " + Integer.toBinaryString(a));
      System.out.println("-60 = " + Integer.toBinaryString(b));

      //signed shift
      c = a >> 1;              
      System.out.println("60 >> 1  = " + Integer.toBinaryString(c));

      //unsigned shift
      c = a >>> 1;            
      System.out.println("60 >>> 1 = " + Integer.toBinaryString(c) );

      c = b >> 1;              
      System.out.println("-60 >> 1  = " + Integer.toBinaryString(c) );

      c = b >>> 1;            
      System.out.println("-60 >>> 1 = " + Integer.toBinaryString(c));
   }
}

Output

60  = 111100
-60 = 11111111111111111111111111000100
60 >> 1  = 11110
60 >>> 1 = 11110
-60 >> 1  = 11111111111111111111111111100010
-60 >>> 1 = 1111111111111111111111111100010

Samual Sam

Published on 20-Jul-2018 15:23:02