Java Math nextAfter() Method

The nextAfter() method of Math class returns the floating-point value adjacent to the first argument in direction of the second argument.

Syntax:

1. public static double nextAfter (double start, double direction)
2. public static float nextAfter (float start, double direction)

Parameters:

The parameter ‘start’ represents the starting floating-point and parameter ‘direction’ represents the value indicating which start or start’s neighbors should be returned.

Return Value:

The nextAfter() method returns the floating-point number adjacent to start in the direction of second parameter.

Special cases of the nextAfter() method are as follows:

• It returns NaN, is either argument passed is NaN.
• It returns unchanged direction, if both arguments are signed zero.
• It returns zero with same sign as start, if start’s value is infinite and direction’s value is such that the result has smaller magnitude.
• It returns ±MAX_VALUE with same sign as start, if start’s value is ±Double.MIN_VALUE and direction’s value is such that the result has smaller magnitude.
• It returns infinity with same sign as start, if start’s value is ±MAX_VALUE and direction’s value is such that the result has larger magnitude.

Example 1:

public class JavaMathNextAfterExample1 {
    public static void main(String[] args) {
        Double a = 1d;
        Double b = 10d;
        // returns the floating-point number adjacent to start in the direction of second parameter
        System.out.println("Floating-point number : "+Math.nextAfter(a,b));
    }
}

Output:

Floating-point number : 1.0000000000000002

Example 2:

public class JavaMathNextAfterExample2 {
    public static void main(String[] args) {
        Double a = 1d;
        Double b = 0.0d/0.0d;
        // returns NaN, is either argument passed is NaN.
        System.out.println("Floating-point number : "+Math.nextAfter(a,b));
    }
}

Output:

Floating-point number : NaN

Example 3:

public class JavaMathNextAfterExample3 {
    public static void main(String[] args) {
        Double a = -0.0d;
        Double b = -0.0d;
        // returns unchanged direction, if both arguments are signed zero.
        System.out.println("Floating-point number : "+Math.nextAfter(a,b));
    }
}

Output:

Floating-point number : -0.0

Example 4:

public class JavaMathNextAfterExample4 {
    public static void main(String[] args) {
        Double start = Double.MIN_VALUE;
        Double direction = -0d;
        /*returns ±Double.MAX_VALUE with same sign as start,
        if start’s value is ±Double.MIN_VALUE and direction’s value is such that the result has smaller magnitude. */
        System.out.println("Floating-point number : "+Math.nextAfter(start,direction));
    }
}

Output:

Floating-point number : 0.0

Example 5:

public class JavaMathNextAfterExample5 {
    public static void main(String[] args) {
        Double start = -Double.MIN_VALUE;
        Double direction = -8765643.98;
        /*returns ±Double.MAX_VALUE with same sign as start,
        if start’s value is ±Double.MIN_VALUE and direction’s value is such that the result has smaller magnitude*/
        System.out.println("Floating-point number : "+Math.nextAfter(start,direction));
    }
}

Output:

Floating-point number : -1.0E-323