JavaFX8：将项目添加到 ObservableList 时出现异常：ConcurrentModificationException

Question

我有一个列出月份值的 ChoiceBox，当用户选择一个值时，它会执行此 lambda 表达式：

private TableView<IncomeFX> tableIncome;
private ChoiceBox<Month> choiceBoxIncomeMonths;

private ChangeListener<Month> setChoiceBoxIncomeMonthsBehaviour(){
    ChangeListener<Month> months = (ObservableValue<? extends Month> observable, Month oldValue, Month newValue) -> {
            incomesData.clear();
            Year selectedYear = choiceBoxIncomeYears.getSelectionModel().getSelectedItem();
            ObservableList<IncomeFX> temp = incomeManager.getIncomesOf(selectedYear, newValue);
            incomesData.addAll(temp);

    };
    return months;
}

以及我如何添加监听器：

choiceBoxIncomeMonths.getSelectionModel().selectedItemProperty().addListener(setChoiceBoxIncomeMonthsBehaviour());

当我点击选择框时，我得到：

Exception in thread "JavaFX Application Thread" java.util.ConcurrentModificationException
at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:386)
at java.util.AbstractList$Itr.next(AbstractList.java:355)
at java.util.AbstractCollection.addAll(AbstractCollection.java:343)
at javafx.collections.ModifiableObservableListBase.addAll(ModifiableObservableListBase.java:99)
at lite.money.ui.MainUI.lambda(MainUI.java:160)
at lite.money.ui.MainUI$$Lambda0/1680764266.changed(Unknown Source)

说明问题出在我调用的那一行：addAll(temp) 我该如何解决这个问题？？？谢谢

Answer 1

由于您没有发布所有代码，我猜测您是运行另一个试图与 JavaFX 数据交互的线程上的代码。当另一个线程尝试这样做时，它将抛出异常，因为只有 JavaFX 线程应该与数据交互。

我真的不能提供更多的建议，因为我没有你正在做的事情的完整代码库来真正说 "yes at line X you are having thread Y access location X when it should not be."

您是否将此添加到另一个线程？你会比我更了解这个应用程序，因为我没有更多的代码可以使用。

Answer 2

这是我解决它的方法，我知道这是一个错误的代码，但我不知道任何其他解决方案，我必须清除它两次，否则项目将被添加，就像我没有清除它一样，如果您有其他解决方案，我会很高兴：

private ChangeListener<Month> setChoiceBoxIncomeMonthsBehaviour(){
    ChangeListener<Month> months = (ObservableValue<? extends Month> observable, Month oldValue, Month newValue) -> {
        if (!lastMonthValuesFired) {
            incomesData.clear();
            Year selectedYear = choiceBoxIncomeYears.getSelectionModel().getSelectedItem();
            ObservableList<IncomeFX> temp = incomeManager.getIncomesOf(selectedYear, newValue);
            ObservableList<IncomeFX> temp2 = FXCollections.observableList(new ArrayList<IncomeFX>());

            for (IncomeFX t : temp) {
                temp2.add(t);
            }
            incomesData.clear();
            incomesData.addAll(temp2);
        }
    };
    return months;
}

Answer 3

我遇到了同样的问题并做了一些研究，这是我发现对我有用的解决方案：

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;

/**
 * Java Program to demonstrate how to deal with
 * ConcurrentModificationException.
 * Unlike the name suggests, this error can come even if only 
 * one thread is modifying the collection e.g. List. 
 * It happens when you modify collection 
 * while iterating over it e.g. adding new element or removing elements.
 * 
 * If you want to remove elements while traversing list then 
 * make sure you use Iterator's remove() method or not ArrayList's remove()
 * method() to avoid ConcurrentModificationExcetpion.
 * 
 * @author WINDOWS 8
 *
 */
public class ConcurrentModExceptionDemo{

    public static void main(String args[]) {

        List<String> listOfPhones = new ArrayList<String>(Arrays.asList(
                "iPhone 6S", "iPhone 6", "iPhone 5", "Samsung Galaxy 4",
                 "Lumia Nokia"));
        
        System.out.println("list of phones: " + listOfPhones);
        
        // Iterating and removing objects from list
        // This is wrong way, will throw ConcurrentModificationException
        for(String phone : listOfPhones){
            if(phone.startsWith("iPhone")){
               // listOfPhones.remove(phone); // will throw exception
            }
        }
        
        // The Right way, iterating elements using Iterator's remove() method
        
        for(Iterator<String> itr = listOfPhones.iterator();
                                   itr.hasNext();){            
            String phone = itr.next();            
            if(phone.startsWith("iPhone")){
                // listOfPhones.remove(phone);  // wrong again
                itr.remove(); // right call
            }
        }
        
        System.out.println("list after removal: " + listOfPhones);

    }

}

Source

JavaFX8：将项目添加到 ObservableList 时出现异常：ConcurrentModificationException

JavaFX8: exception when adding items to ObservableList: ConcurrentModificationException

java

javafx

observablelist