正在用Iterator迭代器循环操作的集合不能调用集合的删除方法，否则就会报异常：ConcurrentModificationException。  (调用迭代器的remove方法可以)

package test;import java.io.*;
import java.util.*;public class Demo {public static void main(String[] args) throws IOException, ClassNotFoundException {ArrayList<String> list=new ArrayList<>();list.add("one");list.add("two");list.add("three");list.add("four");list.add("five");Iterator<String> iterator = list.iterator();while (iterator.hasNext()){String str=iterator.next();if(str.contains("t")){list.remove(str);}}System.out.println(list);}}