Getting random numbers in Java

I would like to get a random value between 1 to 50 in Java.

How may I do that with the help of Math.random();?

How do I bound the values that Math.random() returns?

The first solution is to use the java.util.Random class:

import java.util.Random;

Random rand = new Random();

// Obtain a number between [0 - 49].
int n = rand.nextInt(50);

// Add 1 to the result to get a number from the required range
// (i.e., [1 - 50]).
n += 1;

Another solution is using Math.random():

double random = Math.random() * 49 + 1;

or

int random = (int)(Math.random() * 50 + 1);

int max = 50;
int min = 1;

#1. Using Math.random()

double random = Math.random() * 49 + 1;
or
int random = (int )(Math.random() * 50 + 1);

This will give you value from 1 to 50 in case of int or 1.0 (inclusive) to 50.0 (exclusive) in case of double

> Why? > > random() method returns a random > number between 0.0 and 0.9..., you > multiply it by 50, so upper limit > becomes 0.0 to 49.999... when you add 1, it becomes 1.0 to 50.999..., now when you truncate to int, you get 1 to 50. (thanks to @rup in comments). leepoint's awesome write-up on both the approaches.

#2. Using Random class in Java.

Random rand = new Random(); 
int value = rand.nextInt(50); 

This will give value from 0 to 49.

For 1 to 50: rand.nextInt((max - min) + 1) + min;

Source of some Java Random awesomeness.