Java - Integer reverse() method

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Description

The Java Integer reverse() method returns the value obtained by reversing the order of the bits in the two's complement binary representation of the specified int value.

Declaration

Following is the declaration for java.lang.Integer.reverse() method

public static int reverse(int i)

Parameters

i − This is the int value.

Return Value

This method returns the value obtained by reversing order of the bits in the specified int value.

Exception

NA

Getting Reversed bit int value from a Positive int value Example

The following example shows the usage of Integer reverse() method to get an int by reversing the order of the bits in the two's complement binary representation of the specified int value. We've created a int variable and assigned it a positive int value. Then using toBinaryString() method, we're printing the binary format of the value. Using bitCount(), we're printing the one bits count and then value obtained by reversing order of the bits in the specified int value using reverse() method.

package com.tutorialspoint;

public class IntegerDemo {
   public static void main(String[] args) {
      int i = 170;
      System.out.println("Number = " + i);

      /* returns the string representation of the unsigned integer value 
         represented by the argument in binary (base 2) */
      System.out.println("Binary = " + Integer.toBinaryString(i));

      // returns the number of one-bits 
      System.out.println("Number of one bits = " + Integer.bitCount(i)); 

      /*  returns the value obtained by reversing order of the bits in 
         the specified int value */ 
      System.out.println("After reversing = " + Integer.reverse(i));
   }
} 

Output

Let us compile and run the above program, this will produce the following result −

Number = 170
Binary = 10101010
Number of one bits = 4
After reversing = 1426063360

Getting Reversed bit int value from a Negative int value Example

The following example shows the usage of Integer reverse() method to get an int by reversing the order of the bits in the two's complement binary representation of the specified negative int value. We've created a int variable and assigned it a positive int value. Then using toBinaryString() method, we're printing the binary format of the value. Using bitCount(), we're printing the one bits count and then value obtained by reversing order of the bits in the specified int value using reverse() method.

package com.tutorialspoint;

public class IntegerDemo {
   public static void main(String[] args) {
      int i = -170;
      System.out.println("Number = " + i);

      /* returns the string representation of the unsigned integer value 
         represented by the argument in binary (base 2) */
      System.out.println("Binary = " + Integer.toBinaryString(i));

      // returns the number of one-bits 
      System.out.println("Number of one bits = " + Integer.bitCount(i)); 

      /*  returns the value obtained by reversing order of the bits in 
         the specified int value */ 
      System.out.println("After reversing = " + Integer.reverse(i));
   }
} 

Output

Let us compile and run the above program, this will produce the following result −

Number = -170
Binary = 11111111111111111111111101010110
Number of one bits = 28
After reversing = 1795162111

Getting Reversed bit int value from a Positive Zero value Example

The following example shows the usage of Integer reverse() method to get an int by reversing the order of the bits in the two's complement binary representation of the specified zero value. We've created a int variable and assigned it a positive int value. Then using toBinaryString() method, we're printing the binary format of the value. Using bitCount(), we're printing the one bits count and then value obtained by reversing order of the bits in the specified int value using reverse() method.

package com.tutorialspoint;

public class IntegerDemo {
   public static void main(String[] args) {
      int i = 0;
      System.out.println("Number = " + i);

      /* returns the string representation of the unsigned integer value 
         represented by the argument in binary (base 2) */
      System.out.println("Binary = " + Integer.toBinaryString(i));

      // returns the number of one-bits 
      System.out.println("Number of one bits = " + Integer.bitCount(i)); 

      /*  returns the value obtained by reversing order of the bits in 
         the specified int value */ 
      System.out.println("After reversing = " + Integer.reverse(i));
   }
} 

Output

Let us compile and run the above program, this will produce the following result −

Number = 0
Binary = 0
Number of one bits = 0
After reversing = 0