1.異常java一邊遍歷一邊刪除集合中的元素會報異常ConcurrentModificationException

2.正確的做法如下:

package list;


import java.util.*;


public class Demo {


public static void main(String[] args) {

List<Object> obj = new ArrayList<Object>();

obj.add("a");

obj.add("b");

obj.add("c");

System.out.println("移除前：" + obj.toString());

Iterator<Object> it = obj.iterator();

for(int i=0; i<obj.size(); i++){

System.out.println(i);

Object name = it.next();

if("a".equals(name) || "b".equals(name)){

it.remove();

i--;

}

}

System.out.println("移除後： " + obj.toString());


}


}
 

package set;


import java.util.HashSet;

import java.util.Iterator;

import java.util.Set;


public class Demo {


public static void main(String[] args) {

Set<Object> obj = new HashSet<Object>();

obj.add("a");

obj.add("b");

obj.add("c");

System.out.println("移除前：" + obj.toString());

Iterator<Object> it = obj.iterator();

for(int i=0; i<obj.size(); i++){

System.out.println(i);

Object name = it.next();

if("a".equals(name) || "b".equals(name)){

it.remove();

i--;

}

}

System.out.println("移除後： " + obj.toString());


}


}
 

//遍歷map的方法:

Map<Integer, Integer> map = new HashMap<Integer, Integer>();


for (Map.Entry<Integer, Integer> entry : map.entrySet()) {


System.out.println("Key = " + entry.getKey() + ", Value = " + entry.getValue());


}

原文地址:http://www.cnblogs.com/-liuhuanchao/p/4149806.html(侵刪)

結尾:java8的新streamApi更方便,然而專案中用的是java7-