Conversion to swing

Question

i wrote this program originally in awt, i just converted the buttons to JButtons and now my applet won't initialize, why?
import java.math.*;
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
import java.applet.*;
import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JApplet;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
public class Lab7 extends JApplet implements ActionListener
   private Container pane;
   Picture myPicture1 = new Picture (Color.blue, Color.black, Color.red);
   Picture myPicture2 = new Picture (Color.red, Color.yellow, Color.green);
   private JButton moveButton = new JButton ("Move Picture");
   private JButton sadButton = new JButton ("Sadness");
   private JButton switchButton = new JButton ("Switch Picture");
   int x = 50;
   boolean flag = true;
   public void init()
       setBackground(Color.black);
       moveButton.addActionListener(this);
       //switchButton.addActionListener(this);
       //sadButton.addActionListener(this);
       add(switchButton);
       add(moveButton);
       add(sadButton);
   public void paint(Graphics g)
   myPicture1.draw(g);
   myPicture1.setXY(300, 20);
   myPicture1.setXY(x, 20);
   myPicture1.draw(g);
   public void actionPerformed (ActionEvent ae)
       if (x > getSize().width - 175)
           /* 175 = diameter(150) + xOffset(10) + xIncrement(5)
        * + xOffsetToNotRunToEdge(10) n
        x = 0;
        else
        x += 5;
        repaint();
   class Picture {
       private Color faceColor;
       private Color eyeColor;
        private Color smileColor;
        private int x = 50;
        private int y = 30;
        public Picture (Color f, Color e, Color s)
            faceColor = f;
            eyeColor = e;
            smileColor = s;
        public void setXY(int newX, int newY)
            x = newX;  y = newY;
public void setColors(Color faceColor,
Color eyeColor, Color smileColor)
     this.faceColor = faceColor;
     this.eyeColor = eyeColor;
     this.smileColor = smileColor;
       public Color getFaceColor()
           return faceColor;
       public Color getEyeColor()
           return eyeColor;
           public Color getSmileColor()
               return smileColor;
           public void draw(Graphics g)
               g.setColor(faceColor);
               g.fillOval(x + 10, y + 40, 150, 150);
               g.setColor(eyeColor);
               g.fillOval(x + 60, y + 85, 10, 10);
               g.fillOval(x + 100, y + 85, 10, 10);
               g.setColor(smileColor);
               g.drawArc(x + 35, y + 75, 100, 100, 200, 140);
         class Picture2 {
         private Color topLight;
         private Color midLight;
         private Color lowLight;
         private int x = 50;
         private int y = 30;
         public Picture2 (Color f, Color e, Color s)
            topLight = f;
            midLight = e;
            lowLight = s;
        public void setXY(int newX, int newY)
            x = newX;  y = newY;
public void setColors(Color topLight,
Color midLight, Color lowLight)
     this.topLight = topLight;
     this.midLight = midLight;
     this.lowLight = lowLight;
       public Color gettopLight()
           return topLight;
       public Color getmidLight()
           return midLight;
           public Color getlowLight()
               return lowLight;
           public void draw(Graphics g)
               g.drawRect (100, 100, 50, 150);
               g.setColor(topLight);
               g.fillOval (100, 100, 50, 50);
               g.setColor(midLight);
               g.fillOval(100, 130, 50, 50);
               g.setColor(lowLight);
               g.fillOval(100, 160, 50, 50);
   }

Answer 1

the buttons are being added to the northPanel
import java.math.*;
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
import java.applet.*;
import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JApplet;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
public class Lab7 extends JApplet implements ActionListener
   private Container pane;
   Picture myPicture1 = new Picture (Color.blue, Color.black, Color.red);
   Picture myPicture2 = new Picture (Color.red, Color.yellow, Color.green);
   private JButton moveButton, switchButton, sadButton;
   private JPanel northPanel = new JPanel();
   private JPanel southPanel = new JPanel();
   int x = 50;
   boolean flag = true;
   public void init()
       setBackground(Color.black);
       moveButton.addActionListener(this);
       //switchButton.addActionListener(this);
       //sadButton.addActionListener(this);
       northPanel.add(switchButton);
       northPanel.add(moveButton);
       northPanel.add(sadButton);
       this.getContentPane().setLayout(new BorderLayout(30,5));
       moveButton = new JButton("Move Picture");
       switchButton = new JButton("Switch Picture");
       sadButton = new JButton("Sadness");
   public void paint(Graphics g)
   myPicture1.draw(g);
   myPicture1.setXY(300, 20);
   myPicture1.setXY(x, 20);
   myPicture1.draw(g);
   public void actionPerformed (ActionEvent ae)
       if (x > getSize().width - 175)
           /* 175 = diameter(150) + xOffset(10) + xIncrement(5)
        * + xOffsetToNotRunToEdge(10) n
        x = 0;
        else
        x += 5;
        repaint();
   class Picture {
       private Color faceColor;
       private Color eyeColor;
        private Color smileColor;
        private int x = 50;
        private int y = 30;
        public Picture (Color f, Color e, Color s)
            faceColor = f;
            eyeColor = e;
            smileColor = s;
        public void setXY(int newX, int newY)
            x = newX;  y = newY;
public void setColors(Color faceColor,
Color eyeColor, Color smileColor)
     this.faceColor = faceColor;
     this.eyeColor = eyeColor;
     this.smileColor = smileColor;
       public Color getFaceColor()
           return faceColor;
       public Color getEyeColor()
           return eyeColor;
           public Color getSmileColor()
               return smileColor;
           public void draw(Graphics g)
               g.setColor(faceColor);
               g.fillOval(x + 10, y + 40, 150, 150);
               g.setColor(eyeColor);
               g.fillOval(x + 60, y + 85, 10, 10);
               g.fillOval(x + 100, y + 85, 10, 10);
               g.setColor(smileColor);
               g.drawArc(x + 35, y + 75, 100, 100, 200, 140);
         class Picture2 {
         private Color topLight;
         private Color midLight;
         private Color lowLight;
         private int x = 50;
         private int y = 30;
         public Picture2 (Color f, Color e, Color s)
            topLight = f;
            midLight = e;
            lowLight = s;
        public void setXY(int newX, int newY)
            x = newX;  y = newY;
public void setColors(Color topLight,
Color midLight, Color lowLight)
     this.topLight = topLight;
     this.midLight = midLight;
     this.lowLight = lowLight;
       public Color gettopLight()
           return topLight;
       public Color getmidLight()
           return midLight;
           public Color getlowLight()
               return lowLight;
           public void draw(Graphics g)
               g.drawRect (100, 100, 50, 150);
               g.setColor(topLight);
               g.fillOval (100, 100, 50, 50);
               g.setColor(midLight);
               g.fillOval(100, 130, 50, 50);
               g.setColor(lowLight);
               g.fillOval(100, 160, 50, 50);
   }