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Accepted
F. Iván
Asked: 2020-12-22 03:43:54 +0800 CST 2020-12-22 03:43:54 +0800 CST

Exception java.util.stream.ReferencePipeline$2 is in module java.base of loader 'bootstrap'

  • 772

I have to implement an onClick method for the following button:

<Button layoutX="150.0" mnemonicParsing="false" onMouseClicked="#FilterList" text="Buscar"/>

Well, in the method that I have implemented is the following:

@FXML
private void FilterList() throws IOException{

    List<Player> players = guiApp.getController().getPlayersByName(searchId.getText());     
    displayPlayers(players);
}

GetPlayersByName simulates a database call:

public List<Player> getPlayersByName(String name){
    List<Player> response=new ArrayList<Player>();

    for(Team t : this.getTeams()) 
    {
        response.add((Player) t.getSquad().stream().filter((o->o.getName().contains(name)|| o.getSurname().contains(name))));
    }
    return response;
}

The problem is that when I run it I get the following exception:

Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
    at javafx.fxml/javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1787)
    at javafx.fxml/javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1670)
    at javafx.base/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
    at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
    at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at javafx.base/com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base/com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at javafx.base/com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
    at javafx.base/javafx.event.Event.fireEvent(Event.java:198)
    at javafx.graphics/javafx.scene.Scene$ClickGenerator.postProcess(Scene.java:3564)
    at javafx.graphics/javafx.scene.Scene$ClickGenerator.access$8200(Scene.java:3492)
    at javafx.graphics/javafx.scene.Scene$MouseHandler.process(Scene.java:3860)
    at javafx.graphics/javafx.scene.Scene$MouseHandler.access$1200(Scene.java:3579)
    at javafx.graphics/javafx.scene.Scene.processMouseEvent(Scene.java:1849)
    at javafx.graphics/javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2588)
    at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:397)
    at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
    at java.base/java.security.AccessController.doPrivileged(AccessController.java:389)
    at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$2(GlassViewEventHandler.java:434)
    at javafx.graphics/com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:390)
    at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:433)
    at javafx.graphics/com.sun.glass.ui.View.handleMouseEvent(View.java:556)
    at javafx.graphics/com.sun.glass.ui.View.notifyMouse(View.java:942)
    at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:174)
    at java.base/java.lang.Thread.run(Thread.java:835)
Caused by: java.lang.reflect.InvocationTargetException
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:567)
    at com.sun.javafx.reflect.Trampoline.invoke(MethodUtil.java:76)
    at jdk.internal.reflect.GeneratedMethodAccessor2.invoke(Unknown Source)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:567)
    at javafx.base/com.sun.javafx.reflect.MethodUtil.invoke(MethodUtil.java:273)
    at javafx.fxml/com.sun.javafx.fxml.MethodHelper.invoke(MethodHelper.java:83)
    at javafx.fxml/javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1784)
    ... 33 more
Caused by: java.lang.ClassCastException: class java.util.stream.ReferencePipeline$2 cannot be cast to class edu.uoc.baluocesto.model.Player (java.util.stream.ReferencePipeline$2 is in module java.base of loader 'bootstrap'; edu.uoc.baluocesto.model.Player is in unnamed module of loader 'app')
    at edu.uoc.baluocesto.controller.Database.getPlayersByName(Database.java:214)
    at edu.uoc.baluocesto.view.gui.MainMenuController.FilterList(MainMenuController.java:137)
    ... 44 more

And I have no idea how to fix it, do you have any ideas?

java

1 Answers

  1. Best Answer

    What happens to you is that you are casting a Stream<Player>(which is what the method call returns filter()) to Player. Obviously this fails and hence the exception you get:

    Caused by: java.lang.ClassCastException: class java.util.stream.ReferencePipeline$2 cannot be cast to class edu.uoc.baluocesto.model.Player

    If what you are trying to do is search for all the players that match the search criteria, what you should do is after filter()adding a collect(Collectors.toList())to put all the players found into a list and then add them all to the list responsewith a addAll().

    On the other hand, I always recommend you to separate the procedure of finding the players from that of adding them to the list. Basically to make the code more readable.

        public List<Player> getPlayersByName(String name){
        List<Player> response = new ArrayList<>();

        for(Team t : this.getTeams()) {
            var foundPlayers = t.getSquad().stream()
                    .filter(o -> o.getName().contains(name) || o.getSurname().contains(name))
                    .collect(Collectors.toList());

            response.addAll(foundPlayers);
        }

        return response;
    }

    Now, I can suggest a couple of additional changes so that, using the full power of Streams, you avoid having to use a forand temporary variables like response.

        public List<Player> getPlayersByName2(String name){
        return getTeams().stream()
                .flatMap(t -> t.getSquad().stream())// convierte el stream de Team en un stream de Player
                .filter(o -> o.getName().contains(name) || o.getSurname().contains(name))
                .collect(Collectors.toList());
    }
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