对一集合进行添加和删除操作

Question

//我要完成的功能如下面代码所示,请教,此功能该如何实现
Iterator it = list.iterator();
while(true){while(it.hasNext()){
  Object obj = it.next();//当我进行遍历的时候,另一程序对list添加数据,这句话就报错了,报错信息如下
  //TODO 这里处理obj
  it.remove();
}sleep(20)
}报错信息
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 desktopapplication2.collection.server.SaveData.run(SaveData.java:32)
        at desktopapplication2.collection.util.SocketSwitch.start(SocketSwitch.java:65)
        at desktopapplication2.DesktopApplication2View.jButton1ActionPerformed(DesktopApplication2View.java:619)
        at desktopapplication2.DesktopApplication2View.access$400(DesktopApplication2View.java:26)
        at desktopapplication2.DesktopApplication2View$4.actionPerformed(DesktopApplication2View.java:377)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
        at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
        at java.awt.Component.processMouseEvent(Component.java:6134)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3265)
        at java.awt.Component.processEvent(Component.java:5899)
        at java.awt.Container.processEvent(Container.java:2023)
        at java.awt.Component.dispatchEventImpl(Component.java:4501)
        at java.awt.Container.dispatchEventImpl(Container.java:2081)
        at java.awt.Component.dispatchEvent(Component.java:4331)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4301)
        at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3965)
        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3895)
        at java.awt.Container.dispatchEventImpl(Container.java:2067)
        at java.awt.Window.dispatchEventImpl(Window.java:2458)
        at java.awt.Component.dispatchEvent(Component.java:4331)
        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)

Answer 1

1 使用 CopyOnWriteArrayList 
2 lock

Answer 2

把你list类型都换成CopyOnWriteArrayList

Answer 3

List list = new CopyOnWriteArrayList();
for(Iterator iter = list.iterator(); iter.hasNext();) {
    Object obj = iter.next();
    ...
    if(***) {
        list.remove(obj);
    }
}

Answer 4

同步问题，可以在这个方法上增加synchronized关键词

Answer 5

List list = new CopyOnWriteArrayList();
for(Iterator iter = list.iterator(); iter.hasNext();) {
    Object obj = iter.next();
    ...
    if(***) {
        list.remove(obj);
        //it.remove();这个 remove和上面的这个是同样的效果吗?    }
}

Answer 6

CopyOnWriteArrayList  还真没用过
最多也就用用linkedlist

Answer 7

根据你的意思理解如下，添加和删除都是一个线程完成的import java.util.List;
public class AddListThread implements Runnable {
private List<String> list = null;
public AddListThread(List<String> list){
this.list = list;
}
public void run() {
int i = 0;
while(true){
list.add("String"+i++);
}
}
}
import java.util.Iterator;
import java.util.List;
public class CopyOnWriteArrayListThread implements Runnable {
private List list = null;

public CopyOnWriteArrayListThread(List list){
this.list = list;

}
public void run() {
Iterator iter = list.iterator();
while(true){
while(iter.hasNext()){
String str = (String)iter.next();
System.out.println("-------->" + Thread.currentThread().getName() + "  " + str);
list.remove(str);
try {
Thread.sleep(200);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;public class CopyOnWriteArrayListTest { public static void main(String[] args) {
List<String> list = new CopyOnWriteArrayList();
new Thread(new AddListThread(list)).start();
new Thread(new CopyOnWriteArrayListThread(list)).start();
}
}
结果如下：-------->Thread-1  String0
-------->Thread-1  String1
-------->Thread-1  String2
-------->Thread-1  String3
-------->Thread-1  String4
-------->Thread-1  String5
-------->Thread-1  String6
-------->Thread-1  String7
-------->Thread-1  String8
-------->Thread-1  String9
-------->Thread-1  String10
-------->Thread-1  String11
-------->Thread-1  String12
-------->Thread-1  String13
-------->Thread-1  String14
-------->Thread-1  String15

Answer 8

有没有办法使CopyOnWriteArrayListThread  这个线程一直运行下去, 就算出异常停止运行了也让它自动重新开始运行?