我如何对Java小程序中的Mouse事件做出反应，然后相应地绘制？

Question

My homework is

Write an applet that draw the house shown on the left in Figure 14-32. When the user clicks on the door or windows, they should close. The figure on the right shows the house with its door and windows closed.

I basically want a Java Applet where, if a user clicks on a rectangle, another one is sudden created and drawn.

Here is my code so far.

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class test2 extends JApplet
{
    private final int currentX = 0;


    public void init()
    {
        addMouseListener(new MyMouseListener());
    }

    public void paint (final Graphics g)
    {
        super.paint (g);

        g.drawRect(100, 100, 200, 200);
    }

    private class MyMouseListener extends MouseAdapter
    {

        currentX = e.getX();
    }
}

Answer 1

Take a look at the Java Tutorial | How to Write a Mouse Listener . It will help you determine when and where a user clicks. Once you have these (x,y) coordinates you can check if they lie within the window or the door and if so, draw something else.

Sample code:

   public void mouseClicked(MouseEvent e) {
       int x = e.getX();
       int y = e.getY();

       //check if (x,y) lie in a certain rectangle
       if(x>100 && x<300 && y>100 && y<300){
           //set a variable and repaint
           closeDoors = true;
           repaint();
       }
   }

In your paint method, you need to check if the closeDoors variable is set and if so, draw something else.

public void paint (final Graphics g){
    super.paint (g);
    g.drawRect(100, 100, 200, 200);
    if(closeDoors){
        g.fillRect(100, 100, 200, 200);
    }
}

Answer 2

When the user clicks on the door or windows , then you check if the mouse coordinates are inside the window or door area and, if yes, you replace the drawing of an open door or open window by a drawing of a closed one, which then will look like: they should close .

So, that's what you have to do:

• the "house" model consists of a building, a door and a window, each represented by coordinates
• "door" and "window" can be painted either in "open" or "close" mode
• You need test method to check, if a mouse click occured "on" the windoww or "on" the door

Tip : your current implementation of MouseListener doesn't work at all. You have to override methods from MouseAdapter and put your test in the appropriate method.