JavaFX ComboBox API中的NullPointerException

Question

我的一个屏幕上有一个奇怪的问题,我甚至不知道在哪里看.我在数据库中查找项目并在单独的屏幕(不是实际屏幕,容器)中显示它们的详细信息.

奇怪的是,该程序与大多数项目完美配合,但在某些情况下,它永远不会有效.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.

各位同事,你对这个问题有什么想法或暗示吗？

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)

Answer 1

看起来你ComboBox#setItems(null)在代码中的某处调用过.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null.

您也可以尝试更新到FX 8的开发人员版本,因为那里setItems(null)是禁止的.因此,您将获得更清晰的堆栈跟踪.