The random() method returns a random value that is greater than or equal to 0.0 and less than 1.0.
Example
class Main {
public static void main(String[] args) {
// generates a random number between 0 to 1
System.out.println(Math.random());
}
}
// Output: 0.3034966869965544
Syntax of Math.random()
The syntax of the random() method is:
Math.random()
Note: The random() method is a static method. Hence, we can call the method directly using the class name Math.
random() Parameters
The Math.random() method does not take any parameters.
random() Return Values
- returns a pseudorandom value between 0.0 and 1.0
Note: The values returned are not truly random. Instead values are generated by a definite computational process that satisfies some condition of randomness. Hence called pseudo random values.
Example 1: Java Math.random()
class Main {
public static void main(String[] args) {
// Math.random()
// first random value
System.out.println(Math.random()); // 0.45950063688194265
// second random value
System.out.println(Math.random()); // 0.3388581014886102
// third random value
System.out.println(Math.random()); // 0.8002849308960158
}
}
In the above example, we can see that the random() method returns three different values.
Example 2: Generate Random Number Between 10 and 20
class Main {
public static void main(String[] args) {
int upperBound = 20;
int lowerBound = 10;
// upperBound 20 will also be included
int range = (upperBound - lowerBound) + 1;
System.out.println("Random Numbers between 10 and 20:");
for (int i = 0; i < 10; i ++) {
// generate random number
// (int) convert double value to int
// Math.random() generate value between 0.0 and 1.0
int random = (int)(Math.random() * range) + lowerBound;
System.out.print(random + ", ");
}
}
}
Output
Random Numbers between 10 and 20: 15, 13, 11, 17, 20, 11, 17, 20, 14, 14,
Example 3: Access Random Array Elements
class Main {
public static void main(String[] args) {
// create an array
int[] array = {34, 12, 44, 9, 67, 77, 98, 111};
int lowerBound = 0;
int upperBound = array.length;
// array.length will excluded
int range = upperBound - lowerBound;
System.out.println("Random Array Elements:");
// access 5 random array elements
for (int i = 0; i <= 5; i ++) {
// get random array index
int random = (int)(Math.random() * range) + lowerBound;
System.out.print(array[random] + ", ");
}
}
}
Output
Random Array Elements: 67, 34, 77, 34, 12, 77,