Java math function to convert positive int to negative and negative to positive?

Question

Is there a Java function to convert a positive int to a negative one and a negative int to a positive one?

I\'m looking for a reverse function to perfor

Answer 1

The easiest thing to do is 0- the value

for instance if int i = 5;

0-i would give you -5

and if i was -6;

0- i would give you 6

Answer 2

Necromancing here.
Obviously, x *= -1; is far too simple.

Instead, we could use a trivial binary complement:

number = ~(number - 1) ;

Like this:

import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
    public static void main (String[] args) throws java.lang.Exception
    {
        int iPositive = 15;
        int iNegative = ( ~(iPositive - 1) ) ; // Use extra brackets when using as C preprocessor directive ! ! !...
        System.out.println(iNegative);

        iPositive =  ~(iNegative - 1)  ;
        System.out.println(iPositive);

        iNegative = 0;
        iPositive = ~(iNegative - 1);
        System.out.println(iPositive);


    }
}

That way we can ensure that mediocre programmers don't understand what's going on ;)

Answer 3

You can use Math:

int x = Math.abs(-5);

Answer 4

Yes, as was already noted by Jeffrey Bosboom (Sorry Jeffrey, I hadn't noticed your comment when I answered), there is such a function: Math.negateExact.

and

No, you probably shouldn't be using it. Not unless you need a method reference.

Answer 5

original *= -1;

Simple line of code, original is any int you want it to be.

Answer 6

What about x *= -1; ? Do you really want a library function for this?