JavaFX ComboBox API中的NullPointerException
[英]NullPointerException in the JavaFX ComboBox API
问题描述
I have a strange issue on one of my screens and I really don't even know where to look at. 
我的一个屏幕上有一个奇怪的问题，我什至不知道在哪里看。 I look for items in a database and display details of them in a separate Screen (not an actual screen, a container). 我在数据库中查找项目，并在单独的屏幕（不是实际的屏幕，容器）中显示它们的详细信息。
The strange part is that the program works perfectly well with most of the items, but in some cases, it never works. 奇怪的是，该程序可以很好地与大多数项目配合使用，但是在某些情况下，它永远无法正常工作。 The stack trace doesn't really help me, as none of it belongs to my source code. 堆栈跟踪并没有真正帮助我，因为它们都不属于我的源代码。
Dear fellows, do you have any idea or hint about this issue? 亲爱的同学们，您对此问题有任何想法或提示吗？
java.lang.NullPointerException
at com.sun.javafx.scene.control.skin.ComboBoxListViewSkin.getIndexOfComboBoxValueInItemsList(ComboBoxListViewSkin.java:444)
at com.sun.javafx.scene.control.skin.ComboBoxListViewSkin.updateDisplayNode(ComboBoxListViewSkin.java:392)
at com.sun.javafx.scene.control.skin.ComboBoxListViewSkin.getDisplayNode(ComboBoxListViewSkin.java:229)
at com.sun.javafx.scene.control.skin.ComboBoxBaseSkin.updateDisplayArea(ComboBoxBaseSkin.java:125)
at com.sun.javafx.scene.control.skin.ComboBoxBaseSkin.computePrefHeight(ComboBoxBaseSkin.java:180)
at javafx.scene.Parent.prefHeight(Parent.java:879)
at javafx.scene.layout.Region.prefHeight(Region.java:1384)
at javafx.scene.control.Control.computePrefHeight(Control.java:804)
at javafx.scene.Parent.prefHeight(Parent.java:879)
at javafx.scene.control.Control.prefHeight(Control.java:686)
at javafx.scene.layout.Region.computeChildPrefAreaHeight(Region.java:1599)
at javafx.scene.layout.Region.getMaxAreaHeight(Region.java:1721)
at javafx.scene.layout.Region.computeMaxPrefAreaHeight(Region.java:1689)
at javafx.scene.layout.HBox.computePrefHeight(HBox.java:394)
at javafx.scene.Parent.prefHeight(Parent.java:879)
at javafx.scene.layout.Region.prefHeight(Region.java:1384)
at javafx.scene.layout.Region.computeChildPrefAreaHeight(Region.java:1599)
at javafx.scene.layout.VBox.getAreaHeights(VBox.java:394)
at javafx.scene.layout.VBox.computePrefHeight(VBox.java:373)
at javafx.scene.Parent.prefHeight(Parent.java:879)
at javafx.scene.layout.Region.prefHeight(Region.java:1384)
at javafx.scene.layout.Region.computeChildPrefAreaHeight(Region.java:1599)
at javafx.scene.layout.Region.getMaxAreaHeight(Region.java:1721)
at javafx.scene.layout.Region.computeMaxPrefAreaHeight(Region.java:1689)
at javafx.scene.layout.HBox.computePrefHeight(HBox.java:394)
at javafx.scene.Parent.prefHeight(Parent.java:879)
at javafx.scene.layout.Region.prefHeight(Region.java:1384)
at javafx.scene.layout.Region.computeChildPrefAreaHeight(Region.java:1599)
at javafx.scene.layout.Region.getMaxAreaHeight(Region.java:1721)
at javafx.scene.layout.Region.computeMaxPrefAreaHeight(Region.java:1693)
at javafx.scene.layout.StackPane.computePrefHeight(StackPane.java:320)
at javafx.scene.Parent.prefHeight(Parent.java:879)
at javafx.scene.layout.Region.prefHeight(Region.java:1384)
at com.sun.javafx.scene.control.skin.ScrollPaneSkin.computeScrollNodeSize(ScrollPaneSkin.java:874)
at com.sun.javafx.scene.control.skin.ScrollPaneSkin.layoutChildren(ScrollPaneSkin.java:753)
at javafx.scene.Parent.layout(Parent.java:1018)
at javafx.scene.Parent.layout(Parent.java:1028)
at javafx.scene.Parent.layout(Parent.java:1028)
at javafx.scene.Parent.layout(Parent.java:1028)
at javafx.scene.Parent.layout(Parent.java:1028)
at javafx.scene.Parent.layout(Parent.java:1028)
at javafx.scene.Parent.layout(Parent.java:1028)
at javafx.scene.Parent.layout(Parent.java:1028)
at javafx.scene.Parent.layout(Parent.java:1028)
at javafx.scene.Parent.layout(Parent.java:1028)
at javafx.scene.Scene.layoutDirtyRoots(Scene.java:513)
at javafx.scene.Scene.doLayoutPass(Scene.java:484)
at javafx.scene.Scene.access$3900(Scene.java:169)
at javafx.scene.Scene$ScenePulseListener.pulse(Scene.java:2199)
at com.sun.javafx.tk.Toolkit.firePulse(Toolkit.java:363)
at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:460)
at com.sun.javafx.tk.quantum.QuantumToolkit$9.run(QuantumToolkit.java:329)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.access$100(WinApplication.java:29)
at com.sun.glass.ui.win.WinApplication$3$1.run(WinApplication.java:73)
at java.lang.Thread.run(Thread.java:662)
1 个解决方案
解决方案1
5 已采纳 2013-04-29 15:08:27
It looks like you called ComboBox#setItems(null) somewhere in your code. 看起来您在代码中的某个地方调用了ComboBox#setItems(null) 。 Find all setItems() calls and add debug output of the parameter provided to see if it happens to be null. 查找所有setItems()调用，并添加所提供参数的调试输出，以查看它是否恰好为空。
Also you can try to update to developers versions of FX 8, as setItems(null) was prohibited there. 您也可以尝试更新到FX 8的开发人员版本，因为setItems(null) 禁止 setItems(null) 。 So you will get much more clear stack trace. 这样您将获得更清晰的堆栈跟踪。
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