小程序未初始化

Question

为我正在编写的编码类写了我的第一个java applet。一直说“开始：Applet没有被利用” 我意识到这里可能存在更多问题，但是当applet无法运行时我找不到它们。谁能找到我的错误？

import java.applet.*;  
import java.awt.*;   
import java.awt.event.*;   
import java.awt.image.BufferedImage;   
import java.text.DecimalFormat;   

import javax.swing.JOptionPane;   



public class danielDrinkMachine extends Applet   
{

    private Panel mainPanel;
    private Panel buttons1;
    private Panel buttons2;
    private Panel screen;

    private BufferedImage logo;

    private TextField money;

    private Label screenText;
    private Label titleText;

    private Button cola;
    private Button lemonLimeSoda;
    private Button rootBeer;
    private Button grapeSoda;
    private Button bottledWater;
    private Button formattingButton;

    private double currentMoney;

    private int colaCount = 20;
    private int llCount = 20;
    private int rbCount = 20;
    private int grapeCount = 20;
    private int waterCount = 20;


    private String format ="$#,##0.00";
    private DecimalFormat outFormat =new DecimalFormat(format);

    private final int width = 500;
    private final int height = 500;




    public void init()
    {
        screenText =new Label();

        setSize(WIDTH, HEIGHT);

        buildPanel();   

        add(mainPanel);

        setVisible(true);
    }

    private void buildPanel()
    {

        Label titleText = new Label("ALL DAY's VENDING MACHINES");

        money =new TextField();
        money.setEditable(true);

        Label screenText = new Label("Welcome! Drinks cost $0.75 each!");





        cola =new Button("Cola");
        lemonLimeSoda =new Button("Lemon Lime");
        grapeSoda =new Button("Grape Soda");
        rootBeer =new Button("Root Beer");
        bottledWater =new Button("Water");
        formattingButton =new Button("(Sold Out)");

        cola.addActionListener(new iAmTheListener());
        lemonLimeSoda.addActionListener(new iAmTheListener());
        grapeSoda.addActionListener(new iAmTheListener());
        rootBeer.addActionListener(new iAmTheListener());
        bottledWater.addActionListener(new iAmTheListener());
        formattingButton.addActionListener(new iAmTheListener());


        mainPanel.add(titleText, BorderLayout.PAGE_START);
        mainPanel.add(buttons1, BorderLayout.LINE_START);
        mainPanel.add(buttons2, BorderLayout.LINE_END);
        mainPanel.add(screen, BorderLayout.LINE_END);

        screen.setLayout(new GridLayout(1,2));
        screen.add(screenText);
        screen.add(money);

        buttons1.setLayout(new GridLayout(1,3));
        buttons1.add(cola);
        buttons1.add(lemonLimeSoda);
        buttons1.add(grapeSoda);

        buttons2.setLayout(new GridLayout(1,3));
        buttons2.add(rootBeer);
        buttons2.add(bottledWater);
        buttons2.add(formattingButton);




    }

    private class iAmTheListener implements ActionListener 
    {
        public void actionPerformed(ActionEvent buttonPress)
        {
            String moMoney=money.getText();
            currentMoney =Double.parseDouble(moMoney); 

            if(currentMoney < 0.75)
            {
                int count = 0;

                if(count == 0)
                {
                    JOptionPane.showMessageDialog(null,"Drinks are $0.75 each. Enter more money");  
                    count++;
                }

                if(count == 1)
                {
                    JOptionPane.showMessageDialog(null,"Seriously, its not even real money.");
                    count++;
                }

                if(count == 2)
                {
                    JOptionPane.showMessageDialog(null,"Is this a joke? Its not funny.");
                    count++;
                }

                if(count == 3)
                {
                    JOptionPane.showMessageDialog(null,"Just type put a '1' in the money blank, please.");
                    count ++;
                }

                if(count >= 4)
                {
                    JOptionPane.showMessageDialog(null,"Haha! It's always funnier the " + count + "th time!");
                    count++;
                }

            }
            else if(currentMoney >= 0.75)
            { 
                if(buttonPress.getSource() == cola)
                { 
                    if(colaCount == 0)
                        screenText.setText("Sold out");
                    else if(colaCount != 0)
                    {
                        currentMoney -= 0.75;                               
                        screenText.setText(outFormat.format(currentMoney));
                        currentMoney = 0.0;
                        colaCount--;    
                    }
                    else;
                }
                else if(buttonPress.getSource() ==lemonLimeSoda)
                {
                    if(llCount ==0)
                    {
                        screenText.setText("Sold out");
                    }
                    else if(llCount !=0)
                    {
                        currentMoney -= 0.75;                           
                        screenText.setText(outFormat.format(currentMoney));
                        currentMoney =0.0;
                        llCount--;
                    }
                    else;
                }
                else if(buttonPress.getSource() ==grapeSoda)
                {
                    if(grapeCount ==0)
                    {
                        screenText.setText("Sold out");
                    }
                    else if(grapeCount !=0)
                    {
                        currentMoney -= 0.75;                           
                        screenText.setText(outFormat.format(currentMoney));
                        currentMoney =0.0;
                        grapeCount--;
                    }
                    else;
                }
                else if(buttonPress.getSource() ==rootBeer)
                {
                    if(rbCount ==0)
                    {
                        screenText.setText("Sold out of Root Beer");
                    }
                    else if(rbCount !=0)
                    {
                        currentMoney -= 0.75;                           
                        screenText.setText(outFormat.format(currentMoney));
                        currentMoney =0.0;
                        rbCount--;
                    }
                    else;
                }
                else if(buttonPress.getSource() ==bottledWater)
                {   
                    if(waterCount ==0)
                    {
                        screenText.setText("Sold out");
                    }
                    else if(waterCount !=0)
                    {
                        currentMoney -= 0.75;                           
                        screenText.setText(outFormat.format(currentMoney));
                        currentMoney =0.0;
                        waterCount--;
                    }
                    else;
                }
                else;

            }
        }   
    }
}