Methods in Logo

Java supports methods defined on class types.

public class Rectangle {
    private int width;
    private int height;

    public Rectangle(int width, int height) {
        this.width = width;
        this.height = height;
    }

    // This area method is defined on the Rectangle class.
    public int area() {
        return this.width * this.height;
    }

    // Methods can be defined for instance methods in Java.
    public int perimeter() {
        return 2 * this.width + 2 * this.height;
    }

    public static void main(String[] args) {
        Rectangle r = new Rectangle(10, 5);

        // Here we call the 2 methods defined for our class.
        System.out.println("area: " + r.area());
        System.out.println("perimeter: " + r.perimeter());

        // In Java, all non-primitive variables are references,
        // so there's no need for explicit pointer handling.
        Rectangle rp = r;
        System.out.println("area: " + rp.area());
        System.out.println("perimeter: " + rp.perimeter());
    }
}

To run the program:

$ javac Rectangle.java
$ java Rectangle
area: 50
perimeter: 30
area: 50
perimeter: 30

In Java, methods are always associated with classes, and there’s no distinction between value and pointer receiver types as in some other languages. All non-primitive variables in Java are references to objects.

Java uses object-oriented programming paradigms, where methods are typically instance methods (like area() and perimeter() in this example) that operate on the object’s state. Static methods can also be defined, but they don’t have access to instance variables unless an object is passed to them.

Next, we’ll look at Java’s mechanism for defining abstract types and behaviors: interfaces.

Structs in Logo

Interfaces in Logo

Learn X By Example

Title here

Methods in Logo