JavaFX throws ArrayIndexOutOfBoundsException

Question

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");
}

because my code is not involved means can you post code of the same , without code getting involved null pointer wont be thrown — Rahul Singh, Jun 27 '17 at 09:55
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](https://stackoverflow.com/questions/27769583/calling-clear-on-observablelist-causes-indexoutofboundsexception). — Itai, Jun 27 '17 at 10:03
@RahulSingh: yes, of course, my code causes the problem for sure ;) However, it is not involved in the exception — Defarine, Jun 27 '17 at 11:30
In what circumstances does the method `processBacklogGroupList` get called? Is it possible it is being called while the changes are taking place? — Itai, Jun 27 '17 at 13:33
Why are you generating doing layout on `backlogGroup`? If you modify the child list, this should be triggered automatically; the screen is not updated any faster by doing it manually. If you do not modify the child list, it should be unnecessary to do the layout... Also `processBacklogGroupList` seems to be the only part of the code synchronizing on the containing object. Why do this, if you only allow to call this method from a dedicated thread??? — fabian, Jun 27 '17 at 15:10
Hi - the applyCss and layout is needed to update bounds even on invisible objects. If you need to determine height and width, the layout is needed beforehand - otherwise, width and height may evaluate to 0.0. — Defarine, Jul 05 '17 at 10:48

score 2 · Answer 1 · answered Jul 05 '17 at 10:52

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"

see https://bugs.openjdk.java.net/browse/JDK-8163078 It wouldn't be silly if Oracle would add some code to not throw a Nullpointer exception but point out the fact that the code is not on the JFX Thread. — Wolfgang Fahl, Aug 14 '17 at 17:14

score 0 · Answer 2 · answered Jun 14 '19 at 14:57

0

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

answered Jun 14 '19 at 14:57

A. Vysotskiy

15
7

JavaFX throws ArrayIndexOutOfBoundsException

2 Answers2

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