java - 重复.next()时，Java “ConcurrentModificationException”运行时错误

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Iterating through a Collection, avoiding ConcurrentModificationException when removing objects in a loop

(27个答案)


1年前关闭。




根据运行时错误消息，异常发生在下一行；

VirusData v = iteratorVirusDB.next();

VirusData是带有构造函数和重载构造函数的类，其中包含有关数据库中每种病毒的特定信息，例如；

字符串vName

字符串vDefinition

重载

带有标记化定义的

数组(以xLength组分隔)

带有LCS token 的

数组

以

等级 float

iteratorVirusDB类型的<VirusData>是VirusDB的.iterator()，如下所示:

Iterator<VirusData> iteratorVirusDB = virusDB.iterator();

VirusDB是和<VirusData>类型的ArrayList，我在其中存储病毒对象(此时为name和def)，以便以后使用。

ArrayList <VirusData> virusDB = new ArrayList<VirusData>();

最后，使用上述所有方法的方法都会发生错误:

private void selectDabataseMouseClicked(java.awt.event.MouseEvent evt) {
    while(iteratorVirusDB.hasNext()) {
        VirusData v = iteratorVirusDB.next();               //ERROR LINE
        String vSig = v.signature;
        v.tokens = tokenize.raw(vSig, true, tLength);
        ...
     }
     ...
}

我真的可以提供一些有关如何解决此问题的帮助和建议，以使程序成功运行。波纹管，完整的StackTrace:

run:
Exception in thread "AWT-EventQueue-0" java.util.ConcurrentModificationException
        at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)
        at java.util.AbstractList$Itr.next(AbstractList.java:343)
        at project_clean.Main.selectDabataseMouseClicked(Main.java:275)
        at project_clean.Main.access$100(Main.java:11)
        at project_clean.Main$2.mouseClicked(Main.java:76)
        at java.awt.AWTEventMulticaster.mouseClicked(AWTEventMulticaster.java:253)
        at java.awt.Component.processMouseEvent(Component.java:6270)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)
        at java.awt.Component.processEvent(Component.java:6032)
        at java.awt.Container.processEvent(Container.java:2041)
        at java.awt.Component.dispatchEventImpl(Component.java:4630)
        at java.awt.Container.dispatchEventImpl(Container.java:2099)
        at java.awt.Component.dispatchEvent(Component.java:4460)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4577)
        at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4247)
        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4168)
        at java.awt.Container.dispatchEventImpl(Container.java:2085)
        at java.awt.Window.dispatchEventImpl(Window.java:2478)
        at java.awt.Component.dispatchEvent(Component.java:4460)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

最佳答案

显而易见的解释是您在两次调用之间修改了virusDB。使用迭代器进行迭代时，不得修改 vector (通过Iterator/ListIterator方法除外)。

此代码段将始终抛出ConcurrentModificationException:

import java.util.*;

class VirusData {
}

public class Test {

    public static void main(String[] args) {

        List<VirusData> list = new ArrayList<VirusData>() {{
            add(new VirusData());
            add(new VirusData());
            add(new VirusData());
        }};

        Iterator<VirusData> iterator = list.iterator();

        iterator.next();

        list.remove(0);
        VirusData s = iterator.next();
    }
}

从ConcurrentModificationException的文档中:



如果您打算在每次调用该方法时都对整个数据库进行迭代，则建议您这样做

private void selectDabataseMouseClicked(java.awt.event.MouseEvent evt) {
    Iterator<VirusData> iteratorVirusDB = virusDB.iterator();
    while(iteratorVirusDB.hasNext()) {
        VirusData v = iteratorVirusDB.next();
        String vSig = v.signature;