User Pavlo Plynko
Pavlo Plynko
Java Developer at CodeGym

Java Math.random() Method

Published in the Java Developer group

What is Math.random() Method in Java?

The java.lang.Math.random() method returns a pseudorandom, “double” type number ranging from 0.0 to 1.0.
Hence, the random number generated with the built-in method by Java always lies between 0 and 1.

0.0 ≤ random < 1.0
Kindly note, that the random number is greater than or equal to 0.0 and less than 1.0.

How to Use Math.random() in Java?

Using the Math.random() method is pretty simple even for beginners.

Example 1

Let’s look at a basic example for a clear understanding.

public class RandomTest {

	public static void main(String[] args) {

		double random1 = Math.random();
		double random2 = Math.random();
		
		System.out.println("First Random Number: " + random1);
		System.out.println("Second Random Number: " + random2);
	}
}

Output

First Random Number: 0.5486939400685561 Second Random Number: 0.23550115674999972

Using random() Method within a Range

Calling Math.random() method looks pretty self-explanatory. However, our need for random numbers doesn’t always lie within the range of 0 and 1. For real-life problems, we can operate within other specified ranges as well. Let’s look at an example of using the Math.random() method for a given range, say 1 to 50.

Example 2


public class RandomNumberInRange {
	public static int getRandom(int min, int max) {

		int range = (max - min) + 1; 
     		int random = (int) ((range * Math.random()) + min);
		return random;
	}

	public static void main(String[] args) {
		// Let's play Ludo with 4 Players
		int dieRoll = getRandom(1, 6);
		System.out.println("Red's Turn: " + dieRoll);

		dieRoll = getRandom(1, 6);
		System.out.println("Blue's Turn: " + dieRoll);

		dieRoll = getRandom(1, 6);
		System.out.println("Green's Turn: " + dieRoll);

		dieRoll = getRandom(1, 6);
		System.out.println("Yellow's Turn: " + dieRoll);
	}
}

Output

Red's Turn: 3 Blue's Turn: 2 Green's Turn: 6 Yellow's Turn: 4

Explanation

To get a random number within a range, you need to calculate the range by subtracting min from max. Then after taking a product of range with the Math.rand() you need to add the min number. After casting the double to an int, you have your random number within the specified range. Java Math.random() Method - 1

Conclusion

By the end of this post, we hope you have got yourself familiarized with the Math.random() method in Java. Keep practising for a deeper command of the concept. Till then, keep growing and keep shining!
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Ultimateking Level 0, Sweden
14 August 2021
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