【发布时间】：2015-05-01 14:51:17
【问题描述】：
所以，我有一个问题。我知道问题是什么，但我不知道如何解决它。我给你代码。
public void initialize2(){
txtWaaropGokken = new JTextField();
txtWaaropGokken.setFont(new Font("Tahoma", Font.BOLD, 13));
txtWaaropGokken.setHorizontalAlignment(SwingConstants.CENTER);
txtWaaropGokken.setText("Waar wil je op gokken?");
txtWaaropGokken.setBounds(10, 11, 414, 32);
frame.getContentPane().add(txtWaaropGokken);
txtWaaropGokken.setColumns(10);
txtWaaropGokken.setEditable(false);
JButton ChansesSimples = new JButton("Chanses Simples");
ChansesSimples.setBounds(50, 65, 155, 32);
frame.getContentPane().add(ChansesSimples);
ChansesSimples.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
Random getal = new Random();
int nummer;
nummer=getal.nextInt(37);
txtHetBalletjeRolt = new JTextField();
txtHetBalletjeRolt.setFont(new Font("Tahoma", Font.BOLD, 13));
txtHetBalletjeRolt.setHorizontalAlignment(SwingConstants.CENTER);
txtHetBalletjeRolt.setText("Het balletje is nu aan het rollen.");
txtHetBalletjeRolt.setBounds(10, 11, 414, 32);
frame.getContentPane().add(txtHetBalletjeRolt);
txtHetBalletjeRolt.setColumns(10);
txtHetBalletjeRolt.setEditable(false);
ChansesSimples.setVisible(false);
Douzaines.setVisible(false); \\HERE I DO GET THE ERROR
Colonne.setVisible(false); \\HERE I DO GET THE ERROR
TransversaleSimple.setVisible(false); \\HERE I DO GET THE ERROR
Carre.setVisible(false); \\HERE I DO GET THE ERROR
TransversalePlein.setVisible(false); \\HERE I DO GET THE ERROR
Cheval.setVisible(false); \\HERE I DO GET THE ERROR
Plein.setVisible(false); \\HERE I DO GET THE ERROR
Cheval.setVisible(false); \\HERE I DO GET THE ERROR
if(nummer == 1 || nummer == 3 || nummer == 5 || nummer == 7 || nummer == 9 || nummer == 12 || nummer == 14 || nummer == 16 || nummer == 18 || nummer == 19 || nummer == 21 || nummer == 23 || nummer == 25 || nummer == 27 || nummer == 30 || nummer == 32 || nummer == 34 || nummer == 36){
txtRoodGewonnen = new JTextField();
txtRoodGewonnen.setFont(new Font("Tahoma", Font.BOLD, 13));
txtRoodGewonnen.setHorizontalAlignment(SwingConstants.CENTER);
txtRoodGewonnen.setText("Gefeliciteerd! " + nummer + " is een rood nummer. Je hebt gewonnen!");
txtRoodGewonnen.setBounds(10, 11, 414, 32);
frame.getContentPane().add(txtRoodGewonnen);
txtRoodGewonnen.setColumns(10);
txtRoodGewonnen.setEditable(false);
bedrag = bedrag + inzet * 1;
}
else{
txtRoodVerloren = new JTextField();
txtRoodVerloren.setFont(new Font("Tahoma", Font.BOLD, 13));
txtRoodVerloren.setHorizontalAlignment(SwingConstants.CENTER);
txtRoodVerloren.setText(nummer + " is geen rood nummer. Je hebt verloren.");
txtRoodVerloren.setBounds(10, 11, 414, 32);
frame.getContentPane().add(txtRoodVerloren);
txtRoodVerloren.setColumns(10);
txtRoodVerloren.setEditable(false);
bedrag = bedrag - inzet;
}
txtBedrag = new JTextField();
txtBedrag.setFont(new Font("Tahoma", Font.BOLD, 13));
txtBedrag.setHorizontalAlignment(SwingConstants.CENTER);
txtBedrag.setText("Je hebt nu " + bedrag + " euro.");
txtBedrag.setBounds(10, 50, 414, 32);
frame.getContentPane().add(txtBedrag);
txtBedrag.setColumns(10);
txtBedrag.setEditable(false);
}
});
JButton Douzaines = new JButton("Douzaines");
Douzaines.setBounds(50, 105, 155, 32);
frame.getContentPane().add(Douzaines);
Douzaines.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
}
});
JButton Colonne = new JButton("Colonne");
Colonne.setBounds(50, 145, 155, 32);
frame.getContentPane().add(Colonne);
Colonne.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
}
});
JButton TransversaleSimple = new JButton("Transversale Simple");
TransversaleSimple.setBounds(50, 185, 155, 32);
frame.getContentPane().add(TransversaleSimple);
TransversaleSimple.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
}
});
JButton Carre = new JButton("Carré");
Carre.setBounds(240, 65, 155, 32);
frame.getContentPane().add(Carre);
Carre.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
}
});
JButton TransversalePlein = new JButton("Transversale Plein");
TransversalePlein.setBounds(240, 105, 155, 32);
frame.getContentPane().add(TransversalePlein);
TransversalePlein.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
}
});
JButton Cheval = new JButton("Cheval");
Cheval.setBounds(240, 145, 155, 32);
frame.getContentPane().add(Cheval);
Cheval.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
}
});
JButton Plein = new JButton("Plein");
Plein.setBounds(240, 185, 155, 32);
frame.getContentPane().add(Plein);
Plein.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
ChansesSimples.setVisible(false); \\HERE I DONT GET AN ERROR
Douzaines.setVisible(false); \\HERE I DONT GET AN ERROR
Colonne.setVisible(false); \\HERE I DONT GET AN ERROR
TransversaleSimple.setVisible(false); \\HERE I DONT GET AN ERROR
Carre.setVisible(false); \\HERE I DONT GET AN ERROR
TransversalePlein.setVisible(false); \\HERE I DONT GET AN ERROR
Cheval.setVisible(false); \\HERE I DONT GET AN ERROR
Plein.setVisible(false); \\HERE I DONT GET AN ERROR
Cheval.setVisible(false); \\HERE I DONT GET AN ERROR
}
});
}
问题是，如果程序已经“通过”JButton，如果我然后 setVisible(false)。有用。正如您在 Plein JButton 中看到的那样，我没有收到该代码的任何错误。但是在 Chanses Simples JButton 中，如果我不想出现任何错误，我只能让按钮本身消失。当然我希望玩家可以选择第一个按钮。有什么想法吗？
这是我得到的错误代码：
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at Frame1$3.actionPerformed(Frame1.java:182)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$500(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$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)
【问题讨论】：
-
你在启动 JFrame 吗？
-
通过发布长代码，您限制了愿意帮助您的人数。考虑简化您的示例并发布SSCCE
-
修复此类错误的方法很简单：您阅读堆栈跟踪，注意到异常是从 Frame1.java 的第 182 行抛出的 NullPointerException，因此请转到该行并问自己有什么可能在该行为空。使用调试器会有所帮助。然后，您要么修复代码以确保不为 null 的内容，因为它不应该是，要么通过添加
if测试来修复代码，在访问其成员之一之前检查它是否为 null。我们不知道贴出的代码墙中的第 182 行是什么，所以我们不会费心猜测。 -
是的，我正在启动 JFrame，你是对的，我将发布另一个问题以简化我的问题。
标签： java swing error-handling jframe