Getting graphics to appear on button click

Question

hi guys
could someone please look at my code and point out what i am doing wrong
the applet below displays a christmas tree and 4 buttons.. when a button is clicked it should display another image from a different file in the same directory.. i have started to add the objects to actionPerformed but when i click on the "star" button a star does not appear.. i hope someone can help cuz one of the tutors in the java lab didnt have a clue
applet................
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.awt.BorderLayout;
public class XmasTree2 extends Applet implements ActionListener
     Panel topP;
     Panel mainP;
     Button baub;
     Button pres;
     Button light;
     Button star;
     Color green;
     Object Triangle, Star;
     Polygon triangle1, triangle2, triangle3;
     public void init()
               setSize(600,600);
               baub = new Button("Bauble");
               baub.setBackground(Color.cyan);
               pres = new Button("Present");
               pres.setBackground(Color.cyan);
               light = new Button("Light");
               light.setBackground(Color.cyan);
               star = new Button("Star");
               star.setBackground(Color.cyan);
               add(baub);
               add(pres);
               add(light);
               add(star);
               baub.addActionListener(this);
               pres.addActionListener(this);
               light.addActionListener(this);
               star.addActionListener(this);
               repaint();
     public void paint(Graphics graf)
          triangle1 = new Polygon();
          triangle1.addPoint(300,50);
          triangle1.addPoint(175,220);
          triangle1.addPoint(425,220);
          triangle2 = new Polygon();
          triangle2.addPoint(300,150);
          triangle2.addPoint(100,325);
          triangle2.addPoint(500,325);
          triangle3 = new Polygon();
          triangle3.addPoint(300,250);
          triangle3.addPoint(50,400);
          triangle3.addPoint(550,400);
          green = Color.green;
          graf.setColor(green);
          graf.fillPolygon(triangle1);
          graf.fillPolygon(triangle2);
          graf.fillPolygon(triangle3);
          graf.setColor(new Color(204, 102, 0));
          graf.fillRect(280,400,40,100);
     public void actionPerformed( ActionEvent event )
          if (event.getSource() == star)
                     Star myStar = new Star();
          else if (event.getSource() == baub)
                     System.out.println ("baub");
          else if (event.getSource() == pres)
                     System.out.println ("pres");
          else if (event.getSource() == light)
                     System.out.println ("light");
     public void mousePressed(MouseEvent e)
     public void mouseReleased(MouseEvent e)
     public void mouseEntered(MouseEvent e)
     public void mouseExited(MouseEvent e)
     public void mouseMoved(MouseEvent e)
     public void mouseClicked(MouseEvent e)
     public void mouseDragged(MouseEvent e)
}star class
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.awt.BorderLayout;
public class Star extends Applet
      Polygon sTriangle1, sTriangle2;
     public void paint(Graphics graf)
          sTriangle1 = new Polygon();
          sTriangle1.addPoint(50,50);
          sTriangle1.addPoint(20,100);
          sTriangle1.addPoint(80,100);
          sTriangle2 = new Polygon();
          sTriangle2.addPoint(50,120);
          sTriangle2.addPoint(20,70);
          sTriangle2.addPoint(80,70);
          graf.setColor(Color.yellow);
          graf.fillPolygon(sTriangle1);
          graf.fillPolygon(sTriangle2);
          System.out.println("st");
}

Answer 1

when i click on the "star" button a star does not appear
Your idea for a separate Star class is very good. Your Star extends Applet so to have it
appear and draw itself on your other applet you would have to add it as a component. But
it would have a rectangular shape and then you have backgtound color and obscuration
problems. You could do it this way; if you do, have Star extend Panel instead of Applet
(Applet is a top-level container). Another way is to make Star a graphic class and have it
draw itself into your graphics component, your (XT2) applet. An even more refined approach
would be to do all the drawing in a separate class that extends Panel and add this graphic
component to your applet (center section of a new BorderLayout). Then the applet has a
button panel, action listener and a graphics component. MouseEvent code would go with the
separate graphics class.
Here are some suggestions/ideas for the Star class, in java:
//  <applet code="XT2" width="600" height="600"></applet>
import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
public class XT2 extends Applet implements ActionListener
    Panel topP;
    Panel mainP;
    Button baub;
    Button pres;
    Button light;
    Button star;
    Color green;
    Polygon triangle1, triangle2, triangle3;
    Star[] stars = new Star[0];  // zero-length array
    boolean addStar = false;
    public void init()
        setSize(600,600);
        initTriangles();
        baub = new Button("Bauble");
        baub.setBackground(Color.cyan);
        pres = new Button("Present");
        pres.setBackground(Color.cyan);
        light = new Button("Light");
        light.setBackground(Color.cyan);
        star = new Button("Star");
        star.setBackground(Color.cyan);
        add(baub);
        add(pres);
        add(light);
        add(star);
        baub.addActionListener(this);
        pres.addActionListener(this);
        light.addActionListener(this);
        star.addActionListener(this);
        addMouseListener(decorator);
//        repaint();  // there's nothing to paint yet
    public void paint(Graphics graf)
        green = Color.green;  // this only needs to be done once
        graf.setColor(green);
        graf.fillPolygon(triangle1);
        graf.fillPolygon(triangle2);
        graf.fillPolygon(triangle3);
        graf.setColor(new Color(204, 102, 0));
        graf.fillRect(280,400,40,100);
        graf.setColor(new Color(200, 200, 55));
        // Let the Stars do the work.
        for(int j = 0; j < stars.length; j++)
            stars[j].draw(graf);
    /** Simplify paint method and avoid repitition. */
    private void initTriangles()
        triangle1 = new Polygon();
        triangle1.addPoint(300,50);
        triangle1.addPoint(175,220);
        triangle1.addPoint(425,220);
        triangle2 = new Polygon();
        triangle2.addPoint(300,150);
        triangle2.addPoint(100,325);
        triangle2.addPoint(500,325);
        triangle3 = new Polygon();
        triangle3.addPoint(300,250);
        triangle3.addPoint(50,400);
        triangle3.addPoint(550,400);
    public void actionPerformed( ActionEvent event )
        if (event.getSource() == star)
            // Keep this simple just for this example.
            // You may find a more elegant way to manage
            // user selections for decorating the tree.
            addStar = addStar ? false : true;  // toggle on/off
            System.out.println("addStar = " + addStar);
    /** Just for the sake of a simple example. */
    private MouseListener decorator = new MouseAdapter()
        public void mousePressed(MouseEvent e)
            Point p = e.getPoint();
            if(addStar)
                Star aStar = new Star(p);
                // Add the new Star to the stars array.
                Star[] temp = new Star[stars.length+1];
                System.arraycopy(stars, 0, temp, 0, stars.length);
                temp[stars.length] = aStar;
                stars = temp;
                repaint();
class Star
    Polygon sTriangle1, sTriangle2;
    public Star(Point p)
        // We only need to make this once
        // since the values are hard-coded.
        sTriangle1 = new Polygon();
        sTriangle1.addPoint(50,50);
        sTriangle1.addPoint(20,100);
        sTriangle1.addPoint(80,100);
        sTriangle2 = new Polygon();
        sTriangle2.addPoint(50,120);
        sTriangle2.addPoint(20,70);
        sTriangle2.addPoint(80,70);
        // Find the center of star.
        Rectangle bounds = new Rectangle(20, 50, 60, 70);
        double cx = bounds.getCenterX();
        double cy = bounds.getCenterY();
        // Translate star over Point p.
        int tx = (int)(p.x - cx);
        int ty = (int)(p.y - cy);
        sTriangle1.translate(tx, ty);
        sTriangle2.translate(tx, ty);
    public void draw(Graphics graf)
        graf.setColor(Color.yellow);
        graf.fillPolygon(sTriangle1);
        graf.fillPolygon(sTriangle2);
        System.out.println("st");
}