JavaFX throws ArrayIndexOutOfBoundsException

问题

I'm experimenting with JavaFX labels and Groups with moving them over the screen by mouse dragging. New nodes are added to the animation group from some Threads. However, sometimes I see the following exception out of the sudden - I assume, when some nodes are overlapping. But I don't know what the problem is... because my code is not involved. Does anybody know this exception and root cause (using JDK 1.8.0.-112)? Thanks

'JavaFX Application Thread' lambda$main$68 - Thread[JavaFX Application Thread,5,main] threw an uncaught exception: java.lang.ArrayIndexOutOfBoundsException: -1
    at java.util.ArrayList.elementData(ArrayList.java:418) ~[?:1.8.0_112]
    at java.util.ArrayList.get(ArrayList.java:431) ~[?:1.8.0_112]
    at com.sun.javafx.collections.ObservableListWrapper.get(ObservableListWrapper.java:89) ~[jfxrt.jar:?]
    at com.sun.javafx.collections.VetoableListDecorator.get(VetoableListDecorator.java:306) ~[jfxrt.jar:?]
    at javafx.scene.Parent.updateCachedBounds(Parent.java:1591) ~[jfxrt.jar:?]
    at javafx.scene.Parent.recomputeBounds(Parent.java:1535) ~[jfxrt.jar:?]
    at javafx.scene.Parent.impl_computeGeomBounds(Parent.java:1388) ~[jfxrt.jar:?]
    at javafx.scene.layout.Region.impl_computeGeomBounds(Region.java:3078) ~[jfxrt.jar:?]
    at javafx.scene.Node.updateGeomBounds(Node.java:3579) ~[jfxrt.jar:?]
    at javafx.scene.Node.getGeomBounds(Node.java:3532) ~[jfxrt.jar:?]
    at javafx.scene.Node.getLocalBounds(Node.java:3480) ~[jfxrt.jar:?]
    at javafx.scene.Node.updateTxBounds(Node.java:3643) ~[jfxrt.jar:?]
    at javafx.scene.Node.getTransformedBounds(Node.java:3426) ~[jfxrt.jar:?]
    at javafx.scene.Parent.getChildTransformedBounds(Parent.java:1732) ~[jfxrt.jar:?]
    at javafx.scene.Parent.updateCachedBounds(Parent.java:1596) ~[jfxrt.jar:?]
    at javafx.scene.Parent.recomputeBounds(Parent.java:1535) ~[jfxrt.jar:?]
    at javafx.scene.Parent.impl_computeGeomBounds(Parent.java:1388) ~[jfxrt.jar:?]
    at javafx.scene.Node.updateGeomBounds(Node.java:3579) ~[jfxrt.jar:?]
    at javafx.scene.Node.getGeomBounds(Node.java:3532) ~[jfxrt.jar:?]
    at javafx.scene.Node.getLocalBounds(Node.java:3480) ~[jfxrt.jar:?]
    at javafx.scene.Node.impl_intersectsBounds(Node.java:5015) ~[jfxrt.jar:?]
    at javafx.scene.Parent.impl_pickNodeLocal(Parent.java:705) ~[jfxrt.jar:?]
    at javafx.scene.Node.impl_pickNode(Node.java:4914) ~[jfxrt.jar:?]
    at javafx.scene.Scene$MouseHandler.pickNode(Scene.java:3899) ~[jfxrt.jar:?]
    at javafx.scene.Scene$MouseHandler.access$1600(Scene.java:3485) ~[jfxrt.jar:?]
    at javafx.scene.Scene.pick(Scene.java:1942) ~[jfxrt.jar:?]
    at javafx.scene.Scene.access$6700(Scene.java:159) ~[jfxrt.jar:?]
    at javafx.scene.Scene$MouseHandler.process(Scene.java:3799) ~[jfxrt.jar:?]
    at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485) ~[jfxrt.jar:?]
    at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762) ~[jfxrt.jar:?]
    at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494) ~[jfxrt.jar:?]
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:381) ~[jfxrt.jar:?]
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295) ~[jfxrt.jar:?]
    at java.security.AccessController.doPrivileged(Native Method) ~[?:1.8.0_112]
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$354(GlassViewEventHandler.java:417) ~[jfxrt.jar:?]
    at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389) ~[jfxrt.jar:?]
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:416) ~[jfxrt.jar:?]
    at com.sun.glass.ui.View.handleMouseEvent(View.java:555) ~[jfxrt.jar:?]
    at com.sun.glass.ui.View.notifyMouse(View.java:937) ~[jfxrt.jar:?]
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method) ~[jfxrt.jar:?]
    at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191) ~[jfxrt.jar:?]
    at java.lang.Thread.run(Thread.java:745) [?:1.8.0_112]

I assume, it has something to do with the Label (=BorderPane) adding method. I introduced it to shorten the Java FX Application thread processing time. Is there a problem with that?

private Queue<BacklogGroupAction> todoList = new ConcurrentLinkedQueue<>();

class BacklogGroupAction {
    boolean add;
    boolean visibleState;
    BorderPane dv;

    public BacklogGroupAction(boolean add, boolean visibleState, BorderPane dv) {
        this.add = add;
        this.visibleState = visibleState;
        this.dv = dv;
    }

}

private synchronized void processBacklogGroupList() {
    if (Platform.isFxApplicationThread()) {
        while (!todoList.isEmpty()) {
            BacklogGroupAction p = todoList.poll();
            if (p.add) {
                p.dv.setVisible(p.visibleState);
                backlogGroup.getChildren()
                .add(p.dv);
            } else
                backlogGroup.getChildren()
                .remove(p.dv);
        }
        backlogGroup.applyCss();
        backlogGroup.layout();
    } else
        logger.error("This is not FX Application Thread");
}

回答1:

thanks for all your help. The code above "processBacklogGroupList" is actually correct and works... (so why -1..?)

The problem was in a totally different place, where an animation was defined not running in JFX Application Thread - but exception occured a bit later.

So thanks to @sillyfly for pointing me to the real problem

This usually happens when trying to change an ObservableList bound to a node from a thread other than the JavaFX UI thread, or else when manipulating the list during a change. In both cases usually wrapping the offending call in a Platform.runLater solves the problem. See e.g. this related question. – sillyfly Jun 27 at 10:03"

回答2:

I had got this problem, it was decided by Platform.runLater(() -> {//your code});

来源：https://stackoverflow.com/questions/44777257/javafx-throws-arrayindexoutofboundsexception