meet it

An `if` runs code only when its is `true`.

Picture a fork in the path with a sign asking a question. An if asks a condition like that, inside round brackets. If the answer is yes, Java runs the lines inside. If not, it walks straight past.

Java answers every condition with true or false. A value that can only be one of these is a , and it can live in a box too. To ask whether two numbers match, use two equals signs, ==.

The lines that belong to the if sit in a , between curly brackets. Indent them by four spaces so your eyes can see the block too.

public class Main {
    public static void main(String[] args) {
        int goals = 3;
        System.out.println(goals == 3);
        if (goals == 3) {
            System.out.println("Hat-trick! Take a bow.");
        }
        System.out.println("Full time.");
    }
}

A boolean box can be the whole condition, like if (raining).

guess first

Rain or shine? Guess what this shows.

Guess before you run it. Wrong guesses are how you learn, and nothing is marked.

public class Main {
    public static void main(String[] args) {
        boolean raining = false;
        if (raining) {
            System.out.println("Take a coat.");
        }
        System.out.println("Off you go!");
    }
}

your turn

Your turn. Open the safe.

Pick a secret number for line 3. Then type the very same number as your guess on line 4, and press run.

Your code

output

press run to see what happens

fix it

The quiz has crashed. Can you fix it?

Broken code to fix

output

press run to see what happens

Java stopped at the if line. Look at the sign between answer and 12.
One = puts a value in a box. To ask whether two values match, you need two.
Change = to == on line 4, then press run.

nailed it

your code can make choices now. :D

if runs its block only when the condition is true.
Use == to ask whether two numbers match.
The block sits between curly brackets.

new words in your collection

condition
boolean
block

This lesson isn’t saved. A free account remembers every lesson you finish.

An if runs code only when its condition is true.

Rain or shine? Guess what this shows.

Your turn. Open the safe.

The quiz has crashed. Can you fix it?

your code can make choices now. :D

An `if` runs code only when its is `true`.