FilteredList 在更新时给出 java.lang.ArrayIndexOutOfBoundsException

Question

我创建了一个简单的应用程序来测试过滤列表及其在相应源列表更改时的行为。我还想测试 update 更改，所以我创建了 ObservableList 的 ObservableLists。它比创建具有可观察字段的 Person 等附加类更快、更简单。

代码如下：

    ListChangeListener<ObservableList<String>> changeNotifier = new ListChangeListener<ObservableList<String>>() {
        @Override
        public void onChanged(Change<? extends ObservableList<String>> c) {
            while (c.next()) {
                if (c.wasPermutated()) {
                    System.out.println("permutation");
                } else if (c.wasUpdated()) {
                    System.out.println("update");
                } else {
                    if (c.wasRemoved()) {
                        System.out.println("remove");
                    }
                    if (c.wasAdded()) {
                        System.out.println("add");
                    }
                    if (c.wasReplaced()) {
                        System.out.println("replace");
                    }
                }
            }
        }
    };
    Callback<ObservableList<String>, Observable[]> identityExtractor = new Callback<ObservableList<String>, Observable[]>() {
        @Override
        public Observable[] call(ObservableList<String> param) {
            return new Observable[]{param};
        }
    };
    Predicate<ObservableList<String>> nonEmptyFilter = new Predicate<ObservableList<String>>() {
        @Override
        public boolean test(ObservableList<String> obsl) {
            boolean nonEmpty = ! obsl.isEmpty();
            for (String item : obsl) {
                nonEmpty = nonEmpty && (null != item) && ("" != item);
            };
            return nonEmpty;
        }
    };

    ObservableList<ObservableList<String>> basicSimple = FXCollections.observableArrayList();
    ObservableList<ObservableList<String>> basicComposed = FXCollections.observableArrayList( identityExtractor );

    ObservableList<ObservableList<String>> filteredSimple = basicSimple.filtered( nonEmptyFilter );
    ObservableList<ObservableList<String>> filteredComposed = basicComposed.filtered( nonEmptyFilter );

    System.out.println("Basic testing");

    System.out.println("Add invalid");
    basicSimple.addAll( FXCollections.observableArrayList("") );
    System.out.println( basicSimple );
    System.out.println( filteredSimple );

    System.out.println("Make it valid");
    basicSimple.get(0).addAll("first");
    System.out.println( filteredSimple );

    System.out.println("Add valid");
    basicSimple.addAll( FXCollections.observableArrayList("Second") );
    System.out.println( filteredSimple );

    System.out.println("Composed testing");

    System.out.println("Add invalid");
    basicComposed.addAll( FXCollections.observableArrayList("") );
    System.out.println( basicComposed );
    System.out.println( filteredComposed );

    System.out.println("Make it valid");
    basicComposed.get(0).addAll("first");
    System.out.println( filteredComposed );

    System.out.println("Add valid");
    basicComposed.addAll( FXCollections.observableArrayList("Second") );
    System.out.println( filteredComposed );

我在测试过程中发现了一个奇怪的错误：

[info] Running helloworld.HelloWorld 
Basic testing
Add invalid
[[]]
[]
Make it valid
[]
Add valid
[[Second]]
Composed testing
Add invalid
[[]]
[]
Make it valid
[error] (JavaFX Application Thread) java.lang.ArrayIndexOutOfBoundsException
java.lang.ArrayIndexOutOfBoundsException
        at java.lang.System.arraycopy(Native Method)
        at javafx.collections.transformation.FilteredList.updateFilter(FilteredList.java:298)
        at javafx.collections.transformation.FilteredList.update(FilteredList.java:239)
        at javafx.collections.transformation.FilteredList.sourceChanged(FilteredList.java:137)
        at javafx.collections.transformation.TransformationList.lambda$getListener$16(TransformationList.java:106)
        at javafx.collections.transformation.TransformationList$$Lambda$63/1596532574.onChanged(Unknown Source)
        at javafx.collections.WeakListChangeListener.onChanged(WeakListChangeListener.java:88)
        at com.sun.javafx.collections.ListListenerHelper$SingleChange.fireValueChangedEvent(ListListenerHelper.java:164)
        at com.sun.javafx.collections.ListListenerHelper.fireValueChangedEvent(ListListenerHelper.java:73)
        at javafx.collections.ObservableListBase.fireChange(ObservableListBase.java:233)
        at javafx.collections.ListChangeBuilder.commit(ListChangeBuilder.java:485)
        at javafx.collections.ListChangeBuilder.endChange(ListChangeBuilder.java:541)
        at javafx.collections.ObservableListBase.endChange(ObservableListBase.java:205)
        at com.sun.javafx.collections.ObservableListWrapper.access$200(ObservableListWrapper.java:45)
        at com.sun.javafx.collections.ObservableListWrapper$1$1.invalidated(ObservableListWrapper.java:75)
        at com.sun.javafx.collections.ListListenerHelper$SingleInvalidation.fireValueChangedEvent(ListListenerHelper.java:126)
        at com.sun.javafx.collections.ListListenerHelper.fireValueChangedEvent(ListListenerHelper.java:73)
        at javafx.collections.ObservableListBase.fireChange(ObservableListBase.java:233)
        at javafx.collections.ListChangeBuilder.commit(ListChangeBuilder.java:482)
        at javafx.collections.ListChangeBuilder.endChange(ListChangeBuilder.java:541)
        at javafx.collections.ObservableListBase.endChange(ObservableListBase.java:205)
        at javafx.collections.ModifiableObservableListBase.addAll(ModifiableObservableListBase.java:102)
        at javafx.collections.ObservableListBase.addAll(ObservableListBase.java:245)
        at helloworld.HelloWorld.start(HelloWorld.java:87)
        at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$153(LauncherImpl.java:821)
        at com.sun.javafx.application.LauncherImpl$$Lambda$55/7143454.run(Unknown Source)
        at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$166(PlatformImpl.java:323)
        at com.sun.javafx.application.PlatformImpl$$Lambda$51/397137382.run(Unknown Source)
        at com.sun.javafx.application.PlatformImpl.lambda$null$164(PlatformImpl.java:292)
        at com.sun.javafx.application.PlatformImpl$$Lambda$53/1802784360.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at com.sun.javafx.application.PlatformImpl.lambda$runLater$165(PlatformImpl.java:291)
        at com.sun.javafx.application.PlatformImpl$$Lambda$52/1184782272.run(Unknown Source)
        at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
        at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
        at com.sun.glass.ui.gtk.GtkApplication.lambda$null$45(GtkApplication.java:126)
        at com.sun.glass.ui.gtk.GtkApplication$$Lambda$43/450111611.run(Unknown Source)
        at java.lang.Thread.run(Thread.java:745)
[trace] Stack trace suppressed: run last compile:run for the full output.
[]
Add valid
[[Second]]

basicSimple 和basicComposed 之间的区别在于后者定义了一个提取器，因此它接收更新事件。在处理更新事件的过程中，本机代码引发了异常。我应该考虑什么才能使示例代码正常工作？

---

一点调试

我已将 println 插入到 nonEmptyFilter 谓词测试的末尾。它工作正常，传递给它的 ObservableList 是刚刚更新的预期新值。稍后在执行FilteredList的一些内部代码时发生错误。

Answer 1

所以异常被basicComposed.get(0).addAll("first"); 行抛出，但直觉上它不是get(0) 抛出异常，而是addAll ！？

另一件有趣的事是，如果你删除了identityExtractor，那么异常就消失了吗？此外，只有在 nonEmptyFilter 返回 false 时才会抛出异常！

所以identityExtractor 和nonEmptyFilter 之间存在某种动态，导致addAll 抛出异常。

可以更改当前情况，以便仅在同时以下两个条件成立时抛出异常：

1. basicComposed.get(0).isEmpty() 和
2. basicComposed.get(0).addAll("") // 添加一个空字符串

Answer 2

这看起来像一个错误；我认为它可能与this one 相同，错误报告称它已针对 JavaFX 8u60 进行了修复（对于 8u40 来说可能为时已晚）。

我在 1.8.0_40-ea-b23 上测试过？？和 1.9.0-ea-b49 并且错误出现在两个版本中。如果当前有 1.8.0u60 的 ea 版本，我不确定在哪里可以找到它。