Java lang.Long.reverse() method in Java with Examples

Last Updated : 23 May, 2019
java.lang.Long.reverse() is a built-in function in Java which returns the value obtained by reversing the order of the bits in the two's complement binary representation of the specified long value. Syntax: 
public static long reverse(long num) 
Parameter :
num - the number passed
Returns : 
the value obtained by reversing the order of the bits in the 
two's complement binary representation of the specified long value.
Examples: 
Input : 254 
Output : 9151314442816847872

Input : 8
Output : 1152921504606846976
The program below illustrates the java.lang.Long.reverse() function: Program 1 : CPP 
// Java program that demonstrates the
// Long.reverse() function

// include lang package
import java.lang.*;

public class GFG {

public static void main(String[] args)
    {

        long l = 8;

        System.out.println("The number after reversing bit= "
                           + Long.reverse(l));

        l = 254;
        System.out.println("The number after reversing bit= "
                           + Long.reverse(l));
    }
}
Output: 
The number after reversing bit= 1152921504606846976
The number after reversing bit= 9151314442816847872
Program 2 : When a negative number is passed Java 
// Java program that demonstrates the
// Long.reverse() function
// negative number

// include lang package
import java.lang.*;

public class GFG {

    public static void main(String[] args)
    {

        long l = -8;

        System.out.println("The number after reversing bit= "
                           + Long.reverse(l));

        l = -254;
        System.out.println("The number after reversing bit= "
                           + Long.reverse(l));
    }
}
Output: 
The number after reversing bit= 2305843009213693951
The number after reversing bit= 4683743612465315839
Program 3 : When a decimal number is passed Java 
// Java program that demonstrates the
// Long.reverse() function
// decimal number

// include lang package
import java.lang.*;

public class GFG {

    public static void main(String[] args)
    {

        System.out.println("The number after reversing bit= "
                           + Long.reverse(11.34));
    }
}
Output: 
prog.java:16: error: incompatible types: possible lossy conversion from double to long
                           + Long.reverse(11.34));
Program 4 : When a string number is passed Java 
// Java program that demonstrates the
// Long.reverse() function
// string number

// include lang package
import java.lang.*;

public class GFG {

    public static void main(String[] args)
    {

        System.out.println("The number after reversing bit= "
                           + Long.reverse("12"));
    }
}
Output: 
prog.java:16: error: incompatible types: String cannot be converted to long
                           + Long.reverse("12"));
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