What is the Math.nextDown method in Java?

The nextDown method returns the next adjacent number (floating-point value) of the argument in the direction of negative infinity.

Syntax

float Math.nextDown(float num);
double Math.nextDown(double num);

Parameter

num: The number for which the next adjacent number in the direction of negative infinity is to be returned. num can be either float or double.

Return value

Returns the next adjacent number of the argument in the direction of negative infinity.
Returns NaN if the argument is NaN.
Returns -Float.MIN_VAL if the argument type is float and the value of the argument is 0.
Returns -Double.MIN_VAL if the argument type is double and the value of the argument is 0.
Returns -Infinity if the argument passed is negative infinity.

Code

class HelloWorld {
    public static void main( String args[] ) {
        float num = 10.0f; // we can als use double type with Math.nextDown
        System.out.println("Math.nextDown(10.0) = " + Math.nextDown(num)); 
        num = 10.000001f;
        System.out.println("Math.nextDown(10.000001f) = " + Math.nextDown(num));
        num = -(1.0f/0.0f);  // negative infinity
        System.out.println("Math.nextDown(-(1.0/0.0)) = " + Math.nextDown(num));
        num = 0;
        System.out.println("Math.nextDown(0) = " + Math.nextDown(num));
        System.out.println("Math.nextDown(0) == -Float.MIN_VALUE :" + (Math.nextDown(num) == -Float.MIN_VALUE));
    }
}

In the code above, we used the Math.nextDown function to find the next adjacent floating-point value of the arguments in the direction of negative infinity.

For the number 10.0, the next adjacent floating-point value is 9.999999.
For the number 10.0000001, the next adjacent floating-point value in the negative infinity direction is 10.0.
For the number -(1.0/0.0)(negative infinity), the next adjacent floating-point value in the negative infinity direction is -infinity.
For the number 0, the next adjacent floating-point value in the negative infinity direction is -Float.MIN_VALUE (-1.4E-45).

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