Anyone knows whether this method will work?

Question

Hi,
I am trying out this method to construct an applet but I couldn't get it to work.Does anyone here know whether this method will work and how to debug it.Thanks.
import java.awt.*;
import java.applet.Applet;
import java.awt.event.*;
public class Project extends Applet implements ActionListener {
private Button circle, square;
private Model aModelInstance;
public void init() {
circle = new Button("Circle");
add(circle);
     circle.addActionListener(this);
     square = new Button("Square");
     add(square);
     square.addActionListener(this);
aModelInstance = new Model();
public void paint(Graphics g) {
     aModelInstance.display(g);
     public void actionPerformed(ActionEvent event) {
if (event.getSource() == circle)
aModelInstance.getCircle();
if (event.getSource() == square)
aModelInstance.getSquare();
repaint();
class Model {
     private aModelInstance.display(g)
     public void getCircle() {
     g.setColor(Color.red);
g.fillOval(145,89,122,122);
private aModelInstance.display(g)
     public void getSquare() {
g.setColor(Color.green);
g.fillRect(145,89,122,122);
public void display(Graphics g) {
}

Answer 1

It will work for the most part put there is a few problems that you would have to work out. Most of the problems are in the inner class Model. I commented out a couple of lines in there that did not make sense. In the getSquare() & getCircle() methods you are referring to the variable 'g' where there was no declaration for that variable, in Model. So I modifed the method to have an input parameter of Graphics, that will need to be passed to the method. Then I modified the code in Project so that it passes Graphics when it calls those methods.
The code now compiles cleanly but there is still some work for you to do. You should modify the getSquare() and getCircle() methods to return the Graphics. Then in the actionPerformed() method, call the paint method with the returned Graphics. Good luck.
import java.awt.*;
import java.applet.Applet;
import java.awt.event.*;
public class Project extends Applet implements ActionListener {
private Button circle, square;
private Model aModelInstance;
public void init() {
circle = new Button("Circle");
add(circle);
circle.addActionListener(this);
square = new Button("Square");
add(square);
square.addActionListener(this);
aModelInstance = new Model();
public void paint(Graphics g) {
aModelInstance.display(g);
public void actionPerformed(ActionEvent event) {
if (event.getSource() == circle)
aModelInstance.getCircle(this.getGraphics());
if (event.getSource() == square)
aModelInstance.getSquare(this.getGraphics());
repaint();
class Model {
//private aModelInstance.display(g)
public void getCircle(Graphics g) {
g.setColor(Color.red);
g.fillOval(145,89,122,122);
//private aModelInstance.display(g)
public void getSquare(Graphics g) {
g.setColor(Color.green);
g.fillRect(145,89,122,122);
public void display(Graphics g) {
}