这是OO编程的不正确做法吗？

Question

I'm working on re-writing a paint handler for my api. Is this incorrect practice of OO for my class structure of the PaintManager or is it fine? I feel like it's correct but I wanted some second opinions.

Ignore the height and positional values in the Background class. :p

Answer 1

It's not an incorrect practice. Moreover, whatever you've implemented here is like a Strategy Design Pattern .

Strategy Pattern says
capture the abstraction in an interface, bury implementation details in derived classes.

source

Answer 2

Since you have a PaintManager , I assume that you will have a lot of classes implementing Paintable . Try to have your classes as general as possible, to avoid having to write too many classes.

If you created a class Square extends Paintable for example, the difference in the code would be minimal.

public class Square extends Paintable {
    // the x position
    private int x;

    // the y position
    private int y;

    // the width
    private int w;

    // the height
    private int h;

    // the color
    private Color color;

    public Square(int x, int y, int w, int h, Color color) {
        this.x = x;
        this.y = y;
        this.w = w;
        this.h = h;
        this.color = color;
    }

    // draw method
    public void draw(Graphics g) {
        g.setColor(color.getCOLOR());
        g.drawRect(x, y, w, h);
        g.fillRect(x, y, w, h);
    }
}

Background can be an object of a more general class.

Read Difference between an object and a class for more details