Java 为什么即使没有任何错误,编译器也不运行程序?
我有一个在Eclipse中没有显示任何错误的程序,但是每当我单击run按钮时,什么都不会发生。我在下面附带的编译器控制台中获得代码行Java 为什么即使没有任何错误,编译器也不运行程序?,java,swing,jmenubar,jmenu,Java,Swing,Jmenubar,Jmenu,我有一个在Eclipse中没有显示任何错误的程序,但是每当我单击run按钮时,什么都不会发生。我在下面附带的编译器控制台中获得代码行 import java.awt.*; import javax.swing.*; import java.awt.event.*; public class Transaction extends JFrame { private static final long serialVersionUID = 1L; JFrame frame = new JFra
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class Transaction extends JFrame {
private static final long serialVersionUID = 1L;
JFrame frame = new JFrame("Bank Account - S Standridge");
JMenuBar MenuBar;
JMenu File = new JMenu("File");
JMenu Edit = new JMenu("Edit");
JMenu About = new JMenu("About");
JMenuItem Transaction = new JMenuItem("Transaction");
JMenuItem Summary = new JMenuItem("Summary");
JMenuItem Exit = new JMenuItem("Exit");
private JPanel MenuPanel;
private JPanel TransactionPanel;
private JPanel ButtonPanel;
private JButton calcButton;
private JButton exitButton;
private JMenuItem SummaryMenuItem;
private JMenuItem AboutMenuItem;
private JMenuItem ExitMenuItem;
public Transaction() {
setTitle("Bank Account - S Standridge");
MenuPanel = new JPanel();
TransactionPanel = new JPanel();
ButtonPanel = new JPanel();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(new BorderLayout());
MenuPanel();
TransactionPanel();
BuildButtonPanel();
add(MenuPanel, BorderLayout.NORTH);
add(TransactionPanel, BorderLayout.WEST);
add(ButtonPanel, BorderLayout.SOUTH);
pack();
setVisible(true);
}
private void MenuPanel() {
MenuBar = new JMenuBar();
frame.setJMenuBar(MenuBar);
frame.setVisible(true);
MenuBar.add(File);
MenuBar.add(Edit);
MenuBar.add(About);
File.add(Transaction);
File.add(SummaryMenuItem);
File.add(ExitMenuItem);
SummaryMenuItem.addActionListener(new SummaryMenuListener());
AboutMenuItem.addActionListener(new AboutMenuListener());
}
private void BuildButtonPanel() {
// Create a panel for the buttons.
ButtonPanel = new JPanel();
// Create the buttons.
calcButton = new JButton("Calculate");
exitButton = new JButton("Exit");
// Register the action listeners.
calcButton.addActionListener(new CalcButtonListener());
exitButton.addActionListener(new ExitButtonListener());
// Add the buttons to the button panel.
ButtonPanel.add(calcButton);
ButtonPanel.add(exitButton);
}
private void TransactionPanel()
{
setLayout(new FlowLayout());
JRadioButton b1 = new JRadioButton("A");
// b1.addActionListener(this);
add(b1);
JRadioButton b2 = new JRadioButton("B");
// b2.addActionListener(this);
add(b2);
ButtonGroup bg = new ButtonGroup();
bg.add(b1);
bg.add(b2);
JTextField tf = new JTextField(5);
add(tf);
}
}
class CalcButtonListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
}
}
class SummaryMenuListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
}
}
class ExitButtonListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
System.exit(0);
}
}
class AboutMenuListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
// Displays Message Box
}
}
下一个块是我尝试运行程序时Eclipse的控制台输出
java.lang.reflect.InvocationTargetException
IWAV0052E Invocation Target Exception creating Transaction
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at org.eclipse.ve.internal.java.vce.launcher.remotevm.JFCLauncher$1.run(JFCLauncher.java:59)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$000(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
Caused by: java.lang.NullPointerException
at java.awt.Container.addImpl(Unknown Source)
at java.awt.Container.add(Unknown Source)
at javax.swing.JPopupMenu.add(Unknown Source)
at javax.swing.JMenu.add(Unknown Source)
at Transaction.MenuPanel(Transaction.java:61)
at Transaction.<init>(Transaction.java:37)
... 19 more
在Transaction.java的第61行有一个NullPointerException
我怀疑您需要在执行File.addSummaryMenuItem;之前初始化SummaryMenuItem 在Transaction.java的第61行有一个NullPointerException
我怀疑您需要在执行File.addSummaryMenuItem;之前初始化SummaryMenuItem 让所有变量名都以大写开头是非常令人困惑的。我建议遵循camelCase约定。此外,如果方法的名称与字段菜单面板的名称完全相同,也会让人感到困惑。大多数方法名称都应该包含一些动词。程序可以很容易地编译,但不能运行。例如,考虑Soal.Out.Primt1/0.0。所有的变量名从大写字母开始都是非常混乱的。我建议遵循camelCase约定。此外,如果方法的名称与字段菜单面板的名称完全相同,也会让人感到困惑。大多数方法名称都应该包含一些动词。程序可以很容易地编译,但不能运行。例如,考虑Soal.Out.Primt1/0。我已经将MeNuPANEL对象名称更改为MP,以便对对象与方法和构造函数有不同的名称。我还移动了代码,将操作侦听器添加到上面的“文件”菜单中。我还在构建菜单栏的menuPanel方法之前添加了一个summary方法。然而,所有这些都无济于事。它仍在编译,但不会运行。我在控制台中得到的错误仍然存在。行的原因是:java.lang.NullPointerException at Transaction.menuPanelTransaction.java:64 at Transaction.Transaction.java:37似乎是一个好的开始。因为这是一个很大的变化,我建议你在一个新问题中发布代码。链接到这个问题,并说这是一个后续问题。在这里添加一个链接,我将查看您的新问题。新问题位于:我已将MenuPanel对象名称更改为mp,以便对象的名称与方法和构造函数的名称不同。我还移动了代码,将操作侦听器添加到上面的“文件”菜单中。我还在构建菜单栏的menuPanel方法之前添加了一个summary方法。然而,所有这些都无济于事。它仍在编译,但不会运行。我在控制台中得到的错误仍然存在。行的原因是:java.lang.NullPointerException at Transaction.menuPanelTransaction.java:64 at Transaction.Transaction.java:37似乎是一个好的开始。因为这是一个很大的变化,我建议你在一个新问题中发布代码。链接到这个问题,并说这是一个后续问题。在此处添加链接,我将查看您的新问题。新问题位于: