Java - Math.abs() method example

The Math.abs() function returns the absolute value of a number. 

The absolute value of the number x denoted |x|, is the non-negative value of x without regard to its sign.

Popular usage examples:

public class MathExample {

    public static void main(String[] args) {
        System.out.println( Math.abs(2)     ); // 2
        System.out.println( Math.abs(-2)    ); // 2

        System.out.println( Math.abs(2.54)  ); // 2.54
        System.out.println( Math.abs(-2.54) ); // 2.54

        System.out.println( Math.abs(0)     ); // 0
        System.out.println( Math.abs(3 + 5) ); // 8
        System.out.println( Math.abs(3 - 5) ); // 2
    }
}

1. Documentation

package java.lang;

public final class Math {

    public static int abs(int number) { ... }
    public static long abs(long number) { ... }
    public static float abs(float number) { ... }
    public static double abs(double number) { ... }

}

2. Math.abs() custom implementation

public class CustomMath {

    static double abs(double x) {
        if (x < 0) {
            return -x;
        }
        return x;
    }

    public static void main(String[] args) {
        System.out.println( abs(2.0) ); // 2.0
        System.out.println( abs(-2.0)); // 2.0
        System.out.println( abs(0.0) ); // 0.0
    }
}

Note: there are few ways to change sign to opposite if (x < 0) is true:

• x = -x
• x *= -1
• x = ~x + 1(not for double)

References

1. Absolute value - wikipedia