我一直在研究一个简单的Java应用程序。我有它编译和运行。我做了更改，把它变成了一个Applet。但是，当我完成时，HTML的applet部分显示为空白......没有错误。
我决定恢复更改，以便我可以编译它并在我的IDE中运行它。一旦我这样做，该程序将成功编译，但不会产生我的JFrame。
任何人都可以看到为什么这不起作用......
//Import packages for GUI development.
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.text.DecimalFormat;
import java.io.*;
public class Powell_5 extends JFrame
{
//Left Panel of GUI.
JButton btnSnickers = new JButton("Snickers");
JButton btnButterFinger = new JButton("Butterfinger");
JButton btnLays = new JButton("Lays Chips");
JButton btnCola = new JButton("Coca-Cola");
JButton btnDCola = new JButton("Diet Coke");
JLabel lblQuantity1 = new JLabel(" Quantity:");
JLabel lblQuantity2 = new JLabel(" Quantity:");
JLabel lblQuantity3 = new JLabel(" Quantity:");
JLabel lblQuantity4 = new JLabel(" Quantity:");
JLabel lblQuantity5 = new JLabel(" Quantity:");
JTextField txtSnickers = new JTextField("0",3);
JTextField txtButterFinger = new JTextField("0",3);
JTextField txtLays = new JTextField("0",3);
JTextField txtCola = new JTextField("0",3);
JTextField txtDCola = new JTextField("0",3);
//Right Panel of GUI
JButton btnClear = new JButton("Clear");
JButton btnOrder = new JButton("Order");
JLabel lblEmployee = new JLabel("Employee Number:");
JLabel lblItems = new JLabel("Total Items Selected");
JLabel lblAmount = new JLabel("Total Amount of Order:");
JTextField txtEmployee = new JTextField(5);
JTextField txtItems = new JTextField("0",5);
JTextField txtAmount = new JTextField("$0.00",8);
//Variables for holding dollar amounts.
int intSnickers;
int intButterFinger;
int intLays;
int intCola;
int intDCola;
String strEmployee;
int intTotalItems;
double dblTotalAmount;
StringBuilder BuiltOrder = new StringBuilder();
//Declare variables for main frame
int WINDOW_WIDTH = 640;
int WINDOW_HEIGHT = 235;
//Declare some error string
String strTooMany = "The maximum number or each item that can be selected is 3.";
//Set up to format dollar
DecimalFormat dollar = new DecimalFormat("0.00");
public void Powell_5()
{
//create a window
JFrame window = new JFrame();
//set title of JFrame
window.setTitle("");
//assign constants to window size
window.setSize(WINDOW_WIDTH, WINDOW_HEIGHT);
//specify "X" button property
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Set up Border Layout here
window.setLayout(new BorderLayout());
//Mnemonic for buttons
btnSnickers.setMnemonic(KeyEvent.VK_S);
btnLays.setMnemonic(KeyEvent.VK_L);
btnButterFinger.setMnemonic(KeyEvent.VK_B);
btnCola.setMnemonic(KeyEvent.VK_C);
btnDCola.setMnemonic(KeyEvent.VK_D);
btnClear.setMnemonic(KeyEvent.VK_E);
btnOrder.setMnemonic(KeyEvent.VK_O);
//Set Tooltip
btnClear.setToolTipText("Click here to erase any pending order, and start over");
btnOrder.setToolTipText("Click here to place your order");
//Make quantity, amount and items all read only
txtItems.setEditable(false);
txtSnickers.setEditable(false);
txtButterFinger.setEditable(false);
txtLays.setEditable(false);
txtCola.setEditable(false);
txtDCola.setEditable(false);
txtAmount.setEditable(false);
//Right align all numeric and currency fields.
txtSnickers.setHorizontalAlignment(JTextField.RIGHT);
txtLays.setHorizontalAlignment(JTextField.RIGHT);
txtButterFinger.setHorizontalAlignment(JTextField.RIGHT);
txtCola.setHorizontalAlignment(JTextField.RIGHT);
txtDCola.setHorizontalAlignment(JTextField.RIGHT);
txtAmount.setHorizontalAlignment(JTextField.RIGHT);
txtItems.setHorizontalAlignment(JTextField.RIGHT);
//Create Products Type Panel
JPanel Products = new JPanel();
Products.setLayout(new GridLayout(6,3));
Products.add(btnSnickers);
Products.add(lblQuantity1);
Products.add(txtSnickers);
Products.add(btnButterFinger);
Products.add(lblQuantity2);
Products.add(txtButterFinger);
Products.add(btnLays);
Products.add(lblQuantity3);
Products.add(txtLays);
Products.add(btnCola);
Products.add(lblQuantity4);
Products.add(txtCola);
Products.add(btnDCola);
Products.add(lblQuantity5);
Products.add(txtDCola);
JPanel Details = new JPanel();
Details.setLayout(new GridLayout(5,2));
//add controls to panel
Details.add(lblEmployee);
Details.add(txtEmployee);
Details.add(lblItems);
Details.add(txtItems);
Details.add(lblAmount);
Details.add(txtAmount);
Details.add(btnClear);
Details.add(btnOrder);
//Create button listeners
btnOrder.addActionListener(new btnOrder());
btnClear.addActionListener(new btnClearListener());
btnSnickers.addActionListener(new btnProduct());
btnButterFinger.addActionListener(new btnProduct());
btnLays.addActionListener(new btnProduct());
btnCola.addActionListener(new btnProduct());
btnDCola.addActionListener(new btnProduct());
//Add panels to window
window.add(Products, BorderLayout.WEST);
window.add(Details, BorderLayout.EAST);
//Pack the contents and set visible to true
pack();
window.setVisible(true);
}
private class btnClearListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
intSnickers = 0;
intButterFinger = 0;
intLays = 0;
intCola = 0;
intDCola = 0;
strEmployee = "";
intTotalItems = 0;
dblTotalAmount = 0;
//Clear text fields
txtSnickers.setText("0");
txtButterFinger.setText("0");
txtLays.setText("0");
txtCola.setText("0");
txtDCola.setText("0");
txtEmployee.setText("0");
txtDCola.setText("0");
txtItems.setText("0");
txtAmount.setText("$0.00");
}
}
private class btnProduct implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
if (e.getSource() == btnSnickers)
{
intSnickers++;
if(intSnickers > 3)
{
intSnickers = 3;
JOptionPane.showMessageDialog(null, strTooMany, "Exceeds Maximum Quantity",JOptionPane.WARNING_MESSAGE);
dblTotalAmount = dblTotalAmount - .75 ;
intTotalItems--;
}
txtSnickers.setText(String.valueOf(intSnickers));
}
else if (e.getSource() == btnLays)
{
intLays++;
if(intLays > 3)
{
intLays = 3;
JOptionPane.showMessageDialog(null, strTooMany, "Exceeds Maximum Quantity",JOptionPane.WARNING_MESSAGE);
dblTotalAmount = dblTotalAmount - .75 ;
intTotalItems--;
}
txtLays.setText(String.valueOf(intLays));
}
else if (e.getSource() == btnButterFinger)
{
intButterFinger++;
if(intButterFinger > 3)
{
intButterFinger = 3;
JOptionPane.showMessageDialog(null, strTooMany, "Exceeds Maximum Quantity",JOptionPane.WARNING_MESSAGE);
dblTotalAmount = dblTotalAmount - .75 ;
intTotalItems--;
}
txtButterFinger.setText(String.valueOf(intButterFinger));
}
else if (e.getSource() == btnCola)
{
intCola++;
if(intCola > 3)
{
intCola = 3;
JOptionPane.showMessageDialog(null, strTooMany, "Exceeds Maximum Quantity",JOptionPane.WARNING_MESSAGE);
dblTotalAmount = dblTotalAmount - .75 ;
intTotalItems--;
}
txtCola.setText(String.valueOf(intCola));
}
else if (e.getSource() == btnDCola)
{
intDCola++;
if(intDCola > 3)
{
intDCola = 3;
JOptionPane.showMessageDialog(null, strTooMany, "Exceeds Maximum Quantity",JOptionPane.WARNING_MESSAGE);
dblTotalAmount = dblTotalAmount - .75 ;
intTotalItems--;
}
txtDCola.setText(String.valueOf(intDCola)); }
intTotalItems++;
txtItems.setText(String.valueOf(intTotalItems));
dblTotalAmount = dblTotalAmount + .75 ;
txtAmount.setText(String.valueOf(dollar.format(dblTotalAmount)));
}
}
private class btnOrder implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
strEmployee = txtEmployee.getText();
if (strEmployee.length() == 4 && Character.isLetter(strEmployee.charAt(0)) && Character.isDigit(strEmployee.charAt(1)) && Character.isDigit(strEmployee.charAt(2)) && Character.isDigit(strEmployee.charAt(3)))
{
if (intTotalItems > 0 )
{
if (intSnickers > 0)
BuiltOrder.append( intSnickers + "Snickers" + "\n");
if (intLays > 0)
BuiltOrder.append("intLays + \"Lays\" + \"\\n\"");
JOptionPane.showMessageDialog(null, "Order for Employee " + strEmployee + ": \n" + BuiltOrder + "\n\n Total Items: " + intTotalItems
+ "\n Total Price: $: " + dollar.format(dblTotalAmount));
}
else
{
JOptionPane.showMessageDialog(null, "At least 1 item must be selected.", "Invalid Order Quantity",JOptionPane.ERROR_MESSAGE);
}
}
else
{
JOptionPane.showMessageDialog(null, "The employee code must be 4 digits long.", "Invalid Employee Entry",JOptionPane.ERROR_MESSAGE);
}
}
}
//Main method to create an instance of the class
public static void main(String[] args)
{
new Powell_5();
}
}
答案 0 :(得分：1)
有些值得检查的事情：
jstack，调试器或其他东西来查看是否存在任何死锁或无限循环。其他建议：
JFrame（或JPanel或类似）。JFrame，并且正在创建一个JFrame window。java.awt.EventQueue.invokeLater）时，坚持使用AWT事件派遣线程EDT。答案 1 :(得分：1)
从Powell_5（）声明中删除“void”：
public Powell_5()
{
//etc