Java2D method call without class

Question

I just started to learn Java and tried to draw some rectangles.

I have run this example and can't understand one thing: class ShapesDemo2D has a constructor:

public void init() {
    //Initialize drawing colors
    setBackground(bg);
    setForeground(fg);
}

I understand that setBackground is a method.

• But how can it be called without a class or instance reference?

This is a method of an abstract Component class in Component.java file.

• Shouldn't it be like Component.setBackground(bg) or componentInstance.setBackground(bg)?

But Component is an abstract class, so it can't be instantiated, and it's methods can not be called.

• So how it is possible to call this method?