Random Numbers

Random numbers bring flavor and variety to our programs. Creating random elements in our programs is easy with the use of randomly generated numbers.


CodeHS makes it easy to generate random numbers with its built-in Randomizer method. For example, we can generate a random number between 1 and 4 by doing the following:

var randomNumber = Randomizer.nextInt(1, 4);

The variable, randomNumber, now holds some random value between 1 and 4. This is inclusive. There are four possible random numbers: 1, 2, 3, or 4.

Rolling Dice

We can use random numbers to simulate the act of rolling a die.

var roll = Randomizer.nextInt(1,6);
println("You rolled a " + roll);

Each time we run the above code, the number printed to the screen changes.

More Things to do with the Randomizer

In addition to creating random numbers, the Randomizer can be used to generate a few other random things.

Type Usage
Randomizer.nextInt(low, high); Creates a random number between low and high.
Randomizer.nextBoolean(); Creates a random boolean value - either true or false.
Randomizer.nextFloat(low, high); Creates a random decimal value float between low and high.
Randomizer.nextColor(); Creates a random color.

Flipping a Coin

Now that we can create random boolean values, let's create a simple program to simulate flipping a coin.

var isHeads = Randomizer.nextBoolean();
if (isHeads) {
    println("You flipped heads!");
} else {
    println("You flipped tails!");

Each time we run this code, the variable isHeads is assigned either a true or false boolean value. The program will print either You flipped heads! or You flipped tails! depending on this randomly generated boolean value.