math.random always give 0 result

Question

I am using Ubuntu 14.04.3 LTS and I am studying Java from the book. I tried to follow one example on the book with Ubuntu Terminal and I\'m using Sublime Text. Here is the code

Answer 1

Read the doc :

Returns a double value with a positive sign, greater than or equal to 0.0 and less than 1.0

Therefore, you will always get less than 1, and the cast to int will round it down to 0. Use, for example, a Random object which has a nextInt(int max) method :

Random rd = new Random();
int number1 = rd.nextInt(10);
int number2 = rd.nextInt(10);

Answer 2

Math.random() returns a number greater or equal than 0 and less than 1. What you are looking for is either

 int number1 = (int)(Math.random()*10);
 int number2 = (int)(Math.random()*10);

or

 Random rand = new Random();
 int number1 = rand.nextInt(10);
 int number2 = rand.nextInt(10);

Also, to get random number from given range, use this for Math.random()

int number 3 = min + (int)(Math.random() * ((max - min) + 1))

and for random.nextInt()

int number 4 = random.nextInt(max - min) + min;