Functions in Logo

Functions are central in Java. We’ll learn about functions (also called methods in Java) with a few different examples.

public class Functions {

    // Here's a method that takes two ints and returns
    // their sum as an int.
    public static int plus(int a, int b) {
        // Java requires explicit returns, i.e. it won't
        // automatically return the value of the last
        // expression.
        return a + b;
    }

    // In Java, we can't omit the type for parameters even if they're
    // the same. Each parameter needs its type declared.
    public static int plusPlus(int a, int b, int c) {
        return a + b + c;
    }

    public static void main(String[] args) {
        // Call a method just as you'd expect, with
        // name(args).
        int res = plus(1, 2);
        System.out.println("1+2 = " + res);

        res = plusPlus(1, 2, 3);
        System.out.println("1+2+3 = " + res);
    }
}

To run the program:

$ javac Functions.java
$ java Functions
1+2 = 3
1+2+3 = 6

There are several other features to Java methods. One is method overloading, which allows multiple methods with the same name but different parameter lists. We’ll look at this concept next.