Conditionals

if, else if, and else work as in most C-family languages, condition in parentheses, block in curly braces.

Example: a time-of-day greeting

public class Main {
    public static void main(String[] args) {
        int hour = 14;
        String greeting;

        if (hour < 12) {
            greeting = "Good morning";
        } else if (hour < 18) {
            greeting = "Good afternoon";
        } else {
            greeting = "Good evening";
        }

        System.out.println(greeting);
    }
}

Good afternoon

Notice greeting is declared without a value first, then assigned inside whichever branch actually runs — Java requires it be assigned exactly once along every possible path before it's used, or the compiler refuses to build the program, another example of Java catching a potential mistake before the code ever runs.