Question

I am trying to understand the difference between 2 methods that have the same name. This is the code I am trying to understand…

public class Test {
    public static void main(String[] args) {
        MyPoint p1 = new MyPoint();
        MyPoint p2 = new MyPoint(10, 30.5);
        System.out.println(p1.distance(p2));
        System.out.println(MyPoint.distance(p1, p2));
    }
}

class MyPoint {
    .....   
}

public double distance(MyPoint secondPoint) {
    return distance(this, secondPoint);
}

public static double distance(MyPoint p1, MyPoint p2) {
    return Math.sqrt((p1.x - p2.x) * (p1.x - p2.x) + (p1.y - p2.y) * (p1.y - p2.y));
}

Could someone please explain the difference between the 2 distance() methods. What does the type MyPoint actually mean? Why does 1 of the methods have a single MyPoint object, whereas the other method has 2 MyPoint objects?

Answer 1

MyPoint is the type of the object. In the distance(MyPoint p1, MyPoint p2) method, for example, it means that you are passing in 2 objects to this method – the first object is a MyPoint object called p1, and the second object is another MyPoint object called p2.

The difference between the 2 println statements is that the first one runs the distance(MyPoint) method, and the second one runs the distance(MyPoint, MyPoint) method. Additionally, the first method runs the distance() from the MyPoint p1 object to the one passed in to the method (p2), whereas the second distance() method is a static call which calculates the distance between the 2 MyPoint objects passed in to the method (p1 and p2).