Random Generator Reference

Written by Danielle Kain and Lisa Yan

Random Generators allow you to add randomness to your program. Regardless of what type of random object you want, you will first have to make a Random Generator:


RandomGenerator rgen = new RandomGenerator();

You can make many types of random objects using RandomGenerators. Here are some examples:


                int randomInt = rgen.nextInt(); //Returns a random int

                double randomDouble = rgen.nextDouble(); //Returns a random double

                Color randomCol = rgen.nextColor(); //Returns a random color

boolean randomBoolean = rgen.nextBoolean(); //Returns a random boolean

Integers

The default method call (with no arguments) returns an unbounded integer, which could be very large or very small. To restrict the range of the integers you get, you can specify bounds. So to get an integer between 0 and 10, inclusive, you could do the following:


                int lb = 0;

                int ub = 10;

                int x = rgen.nextInt(lb, ub); // integer in the range [0,10]

Doubles

The default method call returns a double between 0.0 and 1.0. To increase the range of doubles, you can specify bounds:


        double y = rgen.nextDouble(-3, 5.5); // note -3 is casted from integer to double -3.0

Booleans

Unlike integers and doubles, there is a single argument p that defines the behavior of rgen.nextBoolean(p):

Return true with probability p.
Return false with probability 1-p.
p must be a double between 0 and 1.0.
The default value of p is 0.5.


                bool equalProb = rgen.nextBoolean();

                bool unequalProb = rgen.nextBoolean(0.75); // returns true 3/4ths of the time