Java Math.copySign()用法及代碼示例

public static double copySign(double a, double b)
public static float copySign(float a, float b)

a = the argument providing the magnitude of the result
b = the argument providing the sign of the result

This method returns the magnitude of the first argument with the sign of the second argument.

public class CopySignExample1
{
    public static void main(String[] args) 
    {
        double x = 740.4;
        double y = -29.1;
        // return -740.4 because second argument is negative  
        System.out.println(Math.copySign(x, y));
    }
}

-740.4

public class CopySignExample2
{
    public static void main(String[] args) 
    {
        double x = -580.73;
        double y = 26.3;
        // return 580.73 because second argument y is positive
        System.out.println(Math.copySign(x, y));
    }
}

580.73

public class CopySignExample3
{
    public static void main(String[] args) 
    {
        float x = -788.63f;
        float y = 26.9f;
        // return -26.9 because second argument x is negative
        System.out.println(Math.copySign(y, x));
    }
}

-26.9