Java Math.ceil() method

It’s good to familiarize yourself with the ceil function in mathematics before we move to the ceil method in Java.

What is the ceil function in mathematics?

“A ceil function converts a decimal number to the immediate largest integer.” If the number passed is already a whole number or an integer, then the same number is the ceiling value. However, if you pass a null value to the ceil function in mathematics you get a “zero”.

What is the Math.ceil() method in Java?

Java provides a built-in method to compute the ceil function in mathematics. That we can freely use by passing a “double” type argument to the method Math.ceil(). Let’s have a look at some boundary cases prior to moving to the use cases.

• If the parameter “double” is also a mathematical “integer” [eg: 2.0 is the same as 2] - The result is equal to the integer [i-e; 2 itself].
• If the parameter (let parameter = x) is less than 0 but greater than -1 [ -1 > x < 0 ] - Result is equal to negative zero [-0].
• If the parameter is NaN, +0, -0 or ∞ - Result is the same as the parameter.
• If the parameter is “null” - unlike the mathematical ceil function where you get a zero, here you’ll get a java.lang.NullPointerException.

Example

class Main {

  public static void main(String[] args) {

    Double totalStudentsInClass = 25.0;
    Double flourWeightInKgs = 5.13;
    Double aPoundOfOxygenInLitres = 0.3977;
    Double startingArrayIndexInJava = 0.0;
    Double aSelfDrivingCar = Double.NaN;
    Double numberOfStarsInTheSky = Double.POSITIVE_INFINITY;
    // For parameter  [ -1 > x < 0 ]
    Double x = -0.025;


    // using Math.ceil() method
    System.out.println("Total Students In Class = " + Math.ceil(totalStudentsInClass));
    System.out.println("Flour Weight In Kgs = " + Math.ceil(flourWeightInKgs));
    System.out.println("A Pound of Oxygen in Litres = " + Math.ceil(aPoundOfOxygenInLitres));
    System.out.println("Starting Array Index In Java = " + Math.ceil(startingArrayIndexInJava));
    System.out.println("A Self Driving Car = " + Math.ceil(aSelfDrivingCar));
    System.out.println("Number Of Stars In The Sky = " + Math.ceil(numberOfStarsInTheSky));
    System.out.println("Positive Zero = " + Math.ceil(+0.0));
    System.out.println("Negative Zero = " + Math.ceil(-0.0));
    System.out.println("x = " + x + " [ -1 > x < 0 ] = " + Math.ceil(-0.0));
  }

}

Output

Conclusion

For having a sound grip over the java ceil method, we’d recommend you to also have some good background knowledge of the mathematical ceiling function. Having a firm foundation helps to build an even firm basis. Nonetheless, you can always keep learning, growing and as always don’t forget practising!