Random numbers in Java when working with Android

Math.random() returns an double from [0,1[. Random.nextInt(int) returns an int from [0, int[.

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Random rand = new Random();
int n = rand.nextInt(20); // Gives n such that 0 <= n < 20

Documentation:

Returns a pseudorandom, uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence. Thus, from this example, we'll have a number between 0 and 19