我在 JTable 中使用自定义 JComboBox 作为单元格编辑器。当用户使用键盘控件进入单元格时，它会尝试打开弹出窗口。这会导致以下错误:
java.awt.IllegalComponentStateException: component must be showing on the screen to determine its location
at java.awt.Component.getLocationOnScreen_NoTreeLock(Component.java:1964)
at java.awt.Component.getLocationOnScreen(Component.java:1938)
at javax.swing.JPopupMenu.show(JPopupMenu.java:887)
at javax.swing.plaf.basic.BasicComboPopup.show(BasicComboPopup.java:191)
at javax.swing.plaf.basic.BasicComboBoxUI.setPopupVisible(BasicComboBoxUI.java:859)
at javax.swing.JComboBox.setPopupVisible(JComboBox.java:796)
我看过一些文章，说明这是一个已知问题，解决方案是设置:
comboBox.putClientProperty("JComboBox.isTableCellEditor", Boolean.TRUE);
然而这无济于事。无论如何，这应该做什么？
我读过的所有主题和文章都对问题的性质非常模糊。
有没有人对为什么会出现这个问题的性质有任何见解？我的组合框是非常自定义的，因此它有助于了解问题的基础，以便我可以修复代码。
这是在组合框上的焦点获得事件上触发的，该事件被捕获并调用 setPopupVisible(true);
public void focusGained(java.awt.event.FocusEvent e)
{
//if focus is gained then make sure we show the popup if it is suppose to be visible
setPopupVisible(true);
//and highlight the selected text if any
comboTextEditor.setCaretPosition(comboTextEditor.getText().length());
comboTextEditor.moveCaretPosition(0);
}
顺便说一句，我在 Java 1.7_40 中得到与 Java 1.6_45 相同的结果
全栈跟踪:
Exception in thread "AWT-EventQueue-1" java.awt.IllegalComponentStateException: component must be showing on the screen to determine its location
at java.awt.Component.getLocationOnScreen_NoTreeLock(Component.java:1964)
at java.awt.Component.getLocationOnScreen(Component.java:1938)
at javax.swing.JPopupMenu.show(JPopupMenu.java:887)
at javax.swing.plaf.basic.BasicComboPopup.show(BasicComboPopup.java:191)
at javax.swing.plaf.basic.BasicComboBoxUI.setPopupVisible(BasicComboBoxUI.java:859)
at javax.swing.JComboBox.setPopupVisible(JComboBox.java:796)
at com.mbs.generic.view.swing.combobox.AutoCompleteComboBox$1.focusGained(AutoCompleteComboBox.java:185)
at java.awt.AWTEventMulticaster.focusGained(AWTEventMulticaster.java:203)
at java.awt.Component.processFocusEvent(Component.java:6179)
at java.awt.Component.processEvent(Component.java:6046)
at java.awt.Container.processEvent(Container.java:2039)
at java.awt.Component.dispatchEventImpl(Component.java:4653)
at java.awt.Container.dispatchEventImpl(Container.java:2097)
at java.awt.Component.dispatchEvent(Component.java:4481)
at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1848)
at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:901)
at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:513)
at java.awt.Component.dispatchEventImpl(Component.java:4525)
at java.awt.Container.dispatchEventImpl(Container.java:2097)
at java.awt.Component.dispatchEvent(Component.java:4481)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:648)
at java.awt.EventQueue.access$000(EventQueue.java:84)
at java.awt.EventQueue$1.run(EventQueue.java:607)
at java.awt.EventQueue$1.run(EventQueue.java:605)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:98)
at java.awt.EventQueue$2.run(EventQueue.java:621)
at java.awt.EventQueue$2.run(EventQueue.java:619)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:618)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
谢谢
最佳答案
首先，让我解释一下 comboBox.putClientProperty("JComboBox.isTableCellEditor", Boolean.TRUE); 的作用。通常，将鼠标悬停在项目上或按键盘上的箭头键会立即导致 JComboBox 上的项目选择。由于来自 JComboBox 的选择事件将导致单元格编辑过程停止，因此此行为不适用于表格单元格。因此，在设置此特殊客户端属性时，将在弹出列表中显示已选中但尚未在 JComboBox 上设置的项目。只有提交的项目(通过单击或 Enter 键)会更改 JComboBox 上的选定项目，从而导致编辑结束。至少，这适用于 BasicLookAndFeel 及其衍生物。
你遇到的问题完全不同。正如异常消息和堆栈跟踪清楚地表明的那样，外观尝试打开与 JPopupMenu 关联的 JComboBox(根据您的要求)，但它无法确定弹出菜单的屏幕位置，因为您的 JComboBox 未拍摄显示在屏幕上。它想要 JComboBox 的位置的原因是它打开了相对于 JComboBox 的新窗口。
剩下的问题是为什么您从屏幕上未显示的 focusGained 中收到 JComboBox(或为什么您认为您这样做了)。
关于java - jcombobox 作为单元格编辑器 java.awt.IllegalComponentStateException : component must be showing on the screen to determine its location，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/18968815/