Rounding of Numbers in Java

November 12, 2016December 7, 2017 Vertex Academy how to round numbers java, rounding of numbers

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It's one of the articles from our Java Tutorial for Beginners.

There is a Math class in the package java.lang, which contains 3 methods of rounding of numbers with a floating point to the nearest integer:

1.Math.round()

2.Math.floor()

3.Math.ceil()

The names of these methods are self-explanatory.

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Let’s take a look at the example below and see how these methods work:

Example №1

class Test {

	public static void main(String[] args) {

		float num = 5.25f;

		System.out.println(Math.round(num));
		System.out.println(Math.floor(num));
		System.out.println(Math.ceil(num));
	}
}

class Test {

public static void main(String[] args) {

float num = 5.25f;

System.out.println(Math.round(num));

System.out.println(Math.floor(num));

System.out.println(Math.ceil(num));

}

If you run this code on your computer, you will see the following in the console:

5
5.0
6.0

Commentary:

1. Math.round () - this method rounds a number to the nearest integer.

And indeed, at first we have 5.25, but the method gives us 5, because 5 is the closest integer number to 5.25. If we rounded 8.75 with this method, we would get 9, because 9 is the closest integer number to 8.75.

Please note that this method returns a value of the int type (i.e. an integer). At first, we have 5.25 and the method gives us 5 instead of 5.0.

2. Math.floor () - this method rounds a number downward to the nearest integer.

At first, we have 5.25, and the nearest number downward is 5.0. If we rounded the number 8.75 with the help of this method, we would get 8.0, because it 8.0 is the nearest number downward.

You probably now understand why this method is called floor.

Also, please note that this method returns a double-type value. At first, we have the number 5.25, and after rounding we have 5.0: a double type.

3. Math.ceil() - this method rounds a number upward to its nearest integer. At first, we have 5.25, and then this method gives us 6.0. Even if we had 5.01, this method would still return 6.0, because it is the nearest number upward.

That’s why this method is called ceil, which comes from the word "ceiling." Also, please note that this method returns a double-type value.

Below is a table where everything is written schematically:

Next, you should learn about the methods Math.random(), Math.max (), and Math.min(). You can read about them in the following articles:

1.Random number generation in Java

2.How to display the lowest and highest value in Java

You can find more articles in our Java Tutorial for Beginners.