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 :

// 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 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 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 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"));