使用 GUI 时的错误：IllegalStateException
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【中文标题】使用 GUI 时的错误：IllegalStateException【英文标题】：Errors when using GUI: IllegalStateException 【发布时间】：2019-04-19 01:33:31 【问题描述】：我在尝试运行我的程序时不断出错，即使在使用 net beans 制作程序时我没有任何错误。只有当我尝试编译时才会弹出 50 个错误。有人解释说我的JTextField 没有附加到水平组，我以为我修复了它，但似乎没有。
public class TrianglePerimeter extends javax.swing.JFrame
public TrianglePerimeter()
utilizeComponents();
@SuppressWarnings("Not Checked")
private void utilizeComponents()
sideOneInput = new javax.swing.JTextField();
sideTwoInput = new javax.swing.JTextField();
sideThreeInput = new javax.swing.JTextField();
sideOneLabel = new javax.swing.JLabel();
sideTwoLabel = new javax.swing.JLabel();
sideThreeLabel = new javax.swing.JLabel();
findPerimeterButton = new javax.swing.JButton();
perimeterLabel = new javax.swing.JLabel();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setTitle("Perimeter of a Triangle");
findPerimeterButton.setText("Find the Perimeter");
findPerimeterButton.addActionListener(new java.awt.event.ActionListener()
public void actionPerformed(java.awt.event.ActionEvent evt)
findPerimeterButtonActionPerformed(evt);
);
sideOneLabel.setText("Side One");
sideTwoLabel.setText("Side Two");
sideThreeLabel.setText("Side Three");
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(29, 29, 29)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(findPerimeterButton, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(sideOneInput, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(sideTwoInput)
.addComponent(sideThreeInput)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(16, 16, 16)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(sideOneLabel, javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(sideTwoLabel, javax.swing.GroupLayout.Alignment.TRAILING)))
.addGroup(layout.createSequentialGroup()
.addGap(18, 18, 18)
.addComponent(sideThreeLabel)))
.addGap(56, 56, 56)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(perimeterLabel)))))
.addContainerGap(67, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(sideOneInput, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(sideOneLabel))
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(sideTwoInput, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(sideTwoLabel))
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(sideThreeInput, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(sideThreeLabel))
.addGap(18, 18, 18)
.addComponent(findPerimeterButton)
.addContainerGap(27, Short.MAX_VALUE)
));
pack();
private void findPerimeterButtonActionPerformed(java.awt.event.ActionEvent evt)
System.out.println(evt);
try
double tempPerimeter = (Double.parseDouble(sideOneInput.getText())) + (Double.parseDouble(sideTwoInput.getText())) + (Double.parseDouble(sideThreeInput.getText()));
perimeterLabel.setText(tempPerimeter + " is the perimeter");
catch (NumberFormatException e)
System.err.println("NumberFormatException: " + e.getMessage());
public static void main(String args[])
java.awt.EventQueue.invokeLater(() ->
new TrianglePerimeter().setVisible(true);
);
// Variables declaration - do not modify//GEN-BEGIN:variables
private javax.swing.JLabel sideOneLabel;
private javax.swing.JLabel sideTwoLabel;
private javax.swing.JLabel sideThreeLabel;
private javax.swing.JButton findPerimeterButton;
private javax.swing.JLabel perimeterLabel;
private javax.swing.JTextField sideOneInput;
private javax.swing.JTextField sideTwoInput;
private javax.swing.JTextField sideThreeInput;
private javax.swing.JTextField tempTextField;
// End of variables declaration//GEN-END:variables
这些是错误
Exception in thread "AWT-EventQueue-0" java.lang.IllegalStateException: javax.swing.JTextField[,0,0,0x0,invalid,layout=javax.swing.plaf.basic.BasicTextUI$UpdateHandler,alignmentX=0.0,alignmentY=0.0,border=javax.swing.plaf.BorderUIResource$CompoundBorderUIResource@3566d06c,flags=296,maximumSize=,minimumSize=,preferredSize=,caretColor=sun.swing.PrintColorUIResource[r=51,g=51,b=51],disabledTextColor=javax.swing.plaf.ColorUIResource[r=184,g=207,b=229],editable=true,margin=javax.swing.plaf.InsetsUIResource[top=0,left=0,bottom=0,right=0],selectedTextColor=sun.swing.PrintColorUIResource[r=51,g=51,b=51],selectionColor=javax.swing.plaf.ColorUIResource[r=184,g=207,b=229],columns=0,columnWidth=0,command=,horizontalAlignment=LEADING] is not attached to a horizontal group
at javax.swing.GroupLayout.checkComponents(GroupLayout.java:1086)
at javax.swing.GroupLayout.prepare(GroupLayout.java:1040)
at javax.swing.GroupLayout.preferredLayoutSize(GroupLayout.java:878)
at java.awt.Container.preferredSize(Container.java:1799)
at java.awt.Container.getPreferredSize(Container.java:1783)
at javax.swing.JComponent.getPreferredSize(JComponent.java:1664)
at javax.swing.JRootPane$RootLayout.preferredLayoutSize(JRootPane.java:920)
at java.awt.Container.preferredSize(Container.java:1799)
at java.awt.Container.getPreferredSize(Container.java:1783)
at javax.swing.JComponent.getPreferredSize(JComponent.java:1664)
at java.awt.BorderLayout.preferredLayoutSize(BorderLayout.java:719)
at java.awt.Container.preferredSize(Container.java:1799)
at java.awt.Container.getPreferredSize(Container.java:1783)
at java.awt.Window.pack(Window.java:809)
at TrianglePerimeter.TrianglePerimeter.utilizeComponents(TrianglePerimeter.java:96)
at TrianglePerimeter.TrianglePerimeter.<init>(TrianglePerimeter.java:16)
at TrianglePerimeter.TrianglePerimeter.lambda$main$0(TrianglePerimeter.java:111)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:205)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
谁能告诉我哪里出错了？
【问题讨论】：
啊，GroupLayout，你的代码很痛苦。 GroupLayout 是一个非常复杂的布局管理器，旨在供 GUI 编辑器使用，一般不手动编码。我会考虑使用不同的布局管理器，或者甚至改用 MigLayout
很遗憾，因为它的课程我们不能使用另一个布局管理器
然后扩展@MadProgrammer 的建议，如果GroupLayout 是不可协商的，使用GUI 编辑器可以为自己节省很多压力和理智。顺便说一句 - 可悲的是，这门课程的讲师似乎不知道他们在做什么..
【参考方案1】：
哟布里安娜，
我没有足够的时间来解决所有问题，但您的两个最大问题包括未将 perimeterLabel 组件添加到垂直组以及使用并行组开始每个布局。如果您阅读tutorial on group layout from oracle，您会注意到每个布局都以SequentialGroup 开头，而不是并行组。那是因为您需要在引用并行元素之前定义布局中的元素序列。它类似于 2d 数组如何首先声明它包含的数组的数量，然后是每个数组中的元素。
无论如何，我没有添加周边标签，以便您可以查看答案并尝试解决它应该如何定位。我还删除了所有空白（但将您的代码留在那里注释以便您阅读它）。如果您将自动间隙设置为true，则会为您处理大小调整，它将做出响应。
欢迎提问。我认为这应该是解决问题的良好开端。
public class TrianglePerimeter extends javax.swing.JFrame
public TrianglePerimeter()
utilizeComponents();
@SuppressWarnings("Not Checked")
private void utilizeComponents()
sideOneInput = new javax.swing.JTextField();
sideTwoInput = new javax.swing.JTextField();
sideThreeInput = new javax.swing.JTextField();
sideOneLabel = new javax.swing.JLabel();
sideTwoLabel = new javax.swing.JLabel();
sideThreeLabel = new javax.swing.JLabel();
findPerimeterButton = new javax.swing.JButton();
perimeterLabel = new javax.swing.JLabel();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setTitle("Perimeter of a Triangle");
findPerimeterButton.setText("Find the Perimeter");
findPerimeterButton.addActionListener(new java.awt.event.ActionListener()
public void actionPerformed(java.awt.event.ActionEvent evt)
findPerimeterButtonActionPerformed(evt);
);
sideOneLabel.setText("Side One");
sideTwoLabel.setText("Side Two");
sideThreeLabel.setText("Side Three");
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setAutoCreateGaps(true);
layout.setAutoCreateContainerGaps(true);
layout.setHorizontalGroup(
layout.createSequentialGroup()
// .addGap(29, 29, 29)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
// .addGap(16, 16, 16)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(sideOneLabel, javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(sideTwoLabel, javax.swing.GroupLayout.Alignment.TRAILING)))
.addGroup(layout.createSequentialGroup()
// .addGap(18, 18, 18)
.addComponent(sideThreeLabel)))
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(sideOneInput)
.addComponent(sideTwoInput)
.addComponent(sideThreeInput))
// .addGap(56, 56, 56)
)
.addComponent(findPerimeterButton, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
)
// .addContainerGap(67, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createSequentialGroup()
// .addContainerGap()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(sideOneLabel)
.addComponent(sideOneInput, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
// .addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(sideTwoLabel)
.addComponent(sideTwoInput, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
// .addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(sideThreeLabel)
.addComponent(sideThreeInput, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
// .addGap(18, 18, 18)
.addComponent(findPerimeterButton)
// .addContainerGap(27, Short.MAX_VALUE)
);
pack();
private void findPerimeterButtonActionPerformed(java.awt.event.ActionEvent evt)
System.out.println(evt);
try
double tempPerimeter = (Double.parseDouble(sideOneInput.getText())) + (Double.parseDouble(sideTwoInput.getText())) + (Double.parseDouble(sideThreeInput.getText()));
perimeterLabel.setText(tempPerimeter + " is the perimeter");
catch (NumberFormatException e)
System.err.println("NumberFormatException: " + e.getMessage());
public static void main(String args[])
java.awt.EventQueue.invokeLater(() ->
new TrianglePerimeter().setVisible(true);
);
// Variables declaration - do not modify//GEN-BEGIN:variables
private javax.swing.JLabel sideOneLabel;
private javax.swing.JLabel sideTwoLabel;
private javax.swing.JLabel sideThreeLabel;
private javax.swing.JButton findPerimeterButton;
private javax.swing.JLabel perimeterLabel;
private javax.swing.JTextField sideOneInput;
private javax.swing.JTextField sideTwoInput;
private javax.swing.JTextField sideThreeInput;
private javax.swing.JTextField tempTextField;
// End of variables declaration//GEN-END:variables
【讨论】：
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