java Math.random() from -N to N

Question

I need to randomly pick a number (this is in java, using Math.random()) between -N and N. Specifically, in this current case I need to pick a random number between -1 and 1. All the results I've found has explained how to find a random number between some positive numbers.

Right now I'm using this statement, which only covers half of what I need.

double i = Math.random();

Answer 1

For a random number between -n and n:

/**
 * @return a random number, r, in the range -n <= r < n
 */
public static double getRandom(double n) {
   return Math.random()*n*2 - n;
}

Answer 2

Just use:

2 * Math.random() - 1