Question

我创建了一个简单的应用程序来测试过滤列表及其相应源列表更改时的行为。我还要测试更新更改，因此我创建了ObservableList个ObservableList。它比创建具有可观察字段的其他类更快更简单。

代码看起来如此：

    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，本机代码抛出异常。我应该考虑如何使示例代码正常工作？

调试位

我已将println插入到nonEmptyFilter谓词测试的末尾。它正常工作，并传递给它的ObservableList是刚刚更新的预期新值。稍后当FilteredList的某些iternal代码正在执行时会发生错误。

Answer 1

这看起来像一个bug;我认为它可能与this one相同，bug报告称其为JavaFX 8u60修复（对于8u40来说可能太晚了）。

我在1.8.0_40-ea-b23上测试过？和1.9.0-ea-b49两个版本都出现了错误。如果目前有一个1.8.0u60的ea版本，我不知道在哪里可以找到它。

Answer 2

因此，basicComposed.get(0).addAll("first");行会抛出异常，但直觉上反对get(0)而不是addAll抛出异常，而是identityExtractor！

另一件令人感兴趣的事情是，如果删除nonEmptyFilter，那么例外会消失吗？另外，如果identityExtractor返回false，则只会抛出异常！

nonEmptyFilter和addAll之间存在某种动态因素导致basicComposed.get(0).isEmpty()抛出异常。

如果两者以下两个条件成立，则可以更改当前情况以便仅抛出异常：

basicComposed.get(0).addAll("")和
{{1}} //添加空字符串

FilteredList在更新时提供java.lang.ArrayIndexOutOfBoundsException

调试位

2 个答案: