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Java NullPointerException

4 năm trước 669 lượt xem 3 bình luận 4 năm trước

javafx

Chào mọi người
Hiện tại em mới học javafx và làm 1 project thư viện đơn giản
Em đang gặp 1 vấn đề cần được giúp đỡ
Em đã gán sự kiện cho một vài đối tượng, và khi click thay đổi qua lại giữa các sự kiện, em nhận được lỗi là "Exception in thread "JavaFX Application Thread" java.lang.NullPointerException"
mong mn có thể chỉ giúp em cách fix lỗi này
em xin cảm ơn

java


package Backend;

import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.*;
import javafx.util.Callback;

import javax.swing.*;
import java.io.IOException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import java.util.ResourceBundle;

public class Controller {
    @FXML
    private ListView<String> ListWord;

    @FXML
    private List<Word> words = new ArrayList<Word>();

    @FXML
    private TextField wordinput;

    @FXML
    private TextArea VieTranslate = new TextArea();

    @FXML
    private ObservableList<String> list = FXCollections.observableArrayList();

    @FXML
    private Button searchButton;

    private List<String> stringList = new ArrayList<>();

    /**
     * Hiển thị danh sách từ trong ListView.
     */
    public void setListWord(){
        for(int i=0;i<Dictionary.dictionary.size();i++){
            stringList.add(Dictionary.dictionary.get(i).getWordTarget());
        }
        list.setAll(stringList);
        ListWord.setItems(list);
    }

    public void buttonSearch_click(){
        words = DictionaryManagement.dictionarySearcher(wordinput.getText());
        ListWord.getItems().clear();
        for(int i=0;i<words.size();i++){
            ListWord.getItems().add(words.get(i).getWordTarget());
        }
    }

    public void listview_click(){
        ListWord.getSelectionModel().selectedItemProperty().addListener(new ChangeListener<String>() {
            @Override
            public void changed(ObservableValue<? extends String> observable, String oldValue, String newValue) {
                VieTranslate.clear();
                VieTranslate.setText(newValue + " : " + DictionaryManagement.search_target(newValue));
            }
        });
    }
    @FXML
    void initialize() {
        setListWord();
        listview_click();
    }


}
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Lỗi:


"C:\Program Files\Java\jdk1.8.0_301\bin\java.exe" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2020.2.3\lib\idea_rt.jar=59282:C:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2020.2.3\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_301\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_301\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_301\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_301\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_301\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_301\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_301\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_301\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_301\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_301\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_301\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_301\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_301\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_301\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_301\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_301\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_301\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_301\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_301\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_301\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_301\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_301\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_301\jre\lib\rt.jar;C:\Users\Admin\IdeaProjects\Dictionary\out\production\Dictionary" Backend.DictionaryApplication
Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
	at Backend.DictionaryManagement.search_target(DictionaryManagement.java:145)
	at Backend.Controller$1.changed(Controller.java:65)
	at Backend.Controller$1.changed(Controller.java:61)
	at com.sun.javafx.binding.ExpressionHelper$SingleChange.fireValueChangedEvent(ExpressionHelper.java:182)
	at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81)
	at javafx.beans.property.ReadOnlyObjectPropertyBase.fireValueChangedEvent(ReadOnlyObjectPropertyBase.java:74)
	at javafx.beans.property.ReadOnlyObjectWrapper.fireValueChangedEvent(ReadOnlyObjectWrapper.java:102)
	at javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:112)
	at javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:146)
	at javafx.scene.control.SelectionModel.setSelectedItem(SelectionModel.java:102)
	at javafx.scene.control.MultipleSelectionModelBase.lambda$new$0(MultipleSelectionModelBase.java:67)
	at com.sun.javafx.binding.ExpressionHelper$SingleInvalidation.fireValueChangedEvent(ExpressionHelper.java:137)
	at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81)
	at javafx.beans.property.ReadOnlyIntegerPropertyBase.fireValueChangedEvent(ReadOnlyIntegerPropertyBase.java:72)
	at javafx.beans.property.ReadOnlyIntegerWrapper.fireValueChangedEvent(ReadOnlyIntegerWrapper.java:102)
	at javafx.beans.property.IntegerPropertyBase.markInvalid(IntegerPropertyBase.java:113)
	at javafx.beans.property.IntegerPropertyBase.set(IntegerPropertyBase.java:147)
	at javafx.scene.control.SelectionModel.setSelectedIndex(SelectionModel.java:68)
	at javafx.scene.control.MultipleSelectionModelBase.clearSelection(MultipleSelectionModelBase.java:682)
	at javafx.scene.control.ListView$ListViewBitSetSelectionModel$2.onChanged(ListView.java:1222)
	at javafx.collections.WeakListChangeListener.onChanged(WeakListChangeListener.java:88)
	at com.sun.javafx.collections.ListListenerHelper$Generic.fireValueChangedEvent(ListListenerHelper.java:329)
	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 com.sun.javafx.collections.ObservableListWrapper.clear(ObservableListWrapper.java:157)
	at Backend.Controller.buttonSearch_click(Controller.java:54)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71)
	at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275)
	at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1771)
	at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1657)
	at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
	at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
	at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
	at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
	at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
	at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
	at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
	at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
	at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
	at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
	at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
	at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
	at javafx.event.Event.fireEvent(Event.java:198)
	at javafx.scene.Node.fireEvent(Node.java:8411)
	at javafx.scene.control.Button.fire(Button.java:185)
	at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:182)
	at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:96)
	at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89)
	at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
	at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
	at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
	at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
	at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
	at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
	at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
	at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
	at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
	at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
	at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
	at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
	at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
	at javafx.event.Event.fireEvent(Event.java:198)
	at javafx.scene.Scene$MouseHandler.process(Scene.java:3760)
	at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3488)
	at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1765)
	at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2497)
	at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:397)
	at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
	at java.security.AccessController.doPrivileged(Native Method)
	at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$2(GlassViewEventHandler.java:434)
	at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:411)
	at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:433)
	at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
	at com.sun.glass.ui.View.notifyMouse(View.java:941)
	at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
	at com.sun.glass.ui.win.WinApplication.lambda$null$4(WinApplication.java:185)
	at java.lang.Thread.run(Thread.java:748)

Process finished with exit code 0
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Supporter Moderator đã bình luận 4 năm trước

NullPointerException => Bạn đang truy xuất 1 đối tượng bị null nha!

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Chia sẻ kiến thức, cùng nhau phát triển

Java NullPointerException

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