java - 为什么我的 GroupLayout 出现 'exception in main' 错误？

Question

我想使用 GroupLayout 来获取 usernameLabel/Field 和 passwordLabel/Field 显示，如下所示:

用户名:用户名字段
密码:密码字段

我使用的代码如下:

layout.setHorizontalGroup(
            layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
                .addComponent(usernameLabel)
                .addComponent(usernameField) 
                    )
                .addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
                    .addComponent(passwordLabel)
                    .addComponent(passwordField)
                    )
            );

        layout.setVerticalGroup(
            layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
                .addGroup(layout.createSequentialGroup()
                    .addComponent(usernameLabel)
                    .addComponent(usernameField)
                     )
                .addGroup(layout.createSequentialGroup()
                    .addComponent(passwordLabel)
                    .addComponent(passwordLabel)
                    )
            );

这可以编译，但会出现以下错误:

Exception in thread "main" java.lang.IllegalStateException: javax.swing.JPasswordField[,0,0,0x0,invalid,layout=javax.swing.plaf.basic.BasicTextUI$UpdateHandler,alignmentX=0.0,alignmentY=0.0,border=com.apple.laf.AquaTextFieldBorder@5910e440,flags=288,maximumSize=,minimumSize=,preferredSize=,caretColor=javax.swing.plaf.ColorUIResource[r=0,g=0,b=0],disabledTextColor=javax.swing.plaf.ColorUIResource[r=128,g=128,b=128],editable=true,margin=javax.swing.plaf.InsetsUIResource[top=0,left=0,bottom=0,right=0],selectedTextColor=com.apple.laf.AquaImageFactory$SystemColorProxy[r=0,g=0,b=0],selectionColor=com.apple.laf.AquaImageFactory$SystemColorProxy[r=164,g=205,b=255],columns=20,columnWidth=0,command=,horizontalAlignment=LEADING,echoChar=●] is not attached to a vertical group
    at javax.swing.GroupLayout.checkComponents(GroupLayout.java:1090)
    at javax.swing.GroupLayout.prepare(GroupLayout.java:1040)
    at javax.swing.GroupLayout.layoutContainer(GroupLayout.java:910)
    at java.awt.Container.layout(Container.java:1510)
    at java.awt.Container.doLayout(Container.java:1499)
    at java.awt.Container.validateTree(Container.java:1695)
    at java.awt.Container.validateTree(Container.java:1704)
    at java.awt.Container.validateTree(Container.java:1704)
    at java.awt.Container.validateTree(Container.java:1704)
    at java.awt.Container.validateTree(Container.java:1704)
    at java.awt.Container.validate(Container.java:1630)
    at java.awt.Container.validateUnconditionally(Container.java:1667)
    at java.awt.Window.show(Window.java:1033)
    at java.awt.Component.show(Component.java:1671)
    at java.awt.Component.setVisible(Component.java:1623)
    at java.awt.Window.setVisible(Window.java:1014)
    at xWing.GUIlogin.<init>(GUIlogin.java:107)
    at xWing.Driver.main(Driver.java:7)
Exception in thread "AWT-EventQueue-0" java.lang.IllegalStateException: javax.swing.JPasswordField[,0,0,0x0,invalid,layout=javax.swing.plaf.basic.BasicTextUI$UpdateHandler,alignmentX=0.0,alignmentY=0.0,border=com.apple.laf.AquaTextFieldBorder@5910e440,flags=288,maximumSize=,minimumSize=,preferredSize=,caretColor=javax.swing.plaf.ColorUIResource[r=0,g=0,b=0],disabledTextColor=javax.swing.plaf.ColorUIResource[r=128,g=128,b=128],editable=true,margin=javax.swing.plaf.InsetsUIResource[top=0,left=0,bottom=0,right=0],selectedTextColor=com.apple.laf.AquaImageFactory$SystemColorProxy[r=0,g=0,b=0],selectionColor=com.apple.laf.AquaImageFactory$SystemColorProxy[r=164,g=205,b=255],columns=20,columnWidth=0,command=,horizontalAlignment=LEADING,echoChar=●] is not attached to a vertical group
    at javax.swing.GroupLayout.checkComponents(GroupLayout.java:1090)
    at javax.swing.GroupLayout.prepare(GroupLayout.java:1040)
    at javax.swing.GroupLayout.layoutContainer(GroupLayout.java:910)
    at java.awt.Container.layout(Container.java:1510)
    at java.awt.Container.doLayout(Container.java:1499)
    at java.awt.Container.validateTree(Container.java:1695)
    at java.awt.Container.validateTree(Container.java:1704)
    at java.awt.Container.validateTree(Container.java:1704)
    at java.awt.Container.validateTree(Container.java:1704)
    at java.awt.Container.validateTree(Container.java:1704)
    at java.awt.Container.validate(Container.java:1630)
    at java.awt.Window.dispatchEventImpl(Window.java:2744)
    at java.awt.Component.dispatchEvent(Component.java:4711)
    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:76)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
    at java.awt.EventQueue$4.run(EventQueue.java:731)
    at java.awt.EventQueue$4.run(EventQueue.java:729)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
    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)

为什么我会收到此错误，如何修复它？

Resource 1 :我将我的逻辑(即我用来决定哪个组应该并行/顺序的网格逻辑)与此中的答案进行了比较，它似乎是正确的。
Resource 2

Answer 1

看看这个:

            .addGroup(layout.createSequentialGroup()
                .addComponent(passwordLabel)
                .addComponent(passwordLabel)
                )

这看起来不对。为什么要添加两次标签？

如果其中一个应该是 passwordField，这可以解释为什么异常显示有一个 PasswordText 对象未附加到垂直组。