ArrayList的迭代删除问题

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

public class Test {

public static void main(String[] args) {
List<String> list = new ArrayList<>(2);
list.add("a");
list.add("b");
list.add("c");
list.add("d");
//至此list的modCount值为4
Iterator<String> it = list.iterator();
//list的modCount值为4，it的expectedModCount值为4
while(it.hasNext()){//迭代成功的必要条件是：modCount == expectedModCount
System.out.println(it.next());
list.remove(2);
//list的modCount值为5，it的expectedModCount值为4，导致下一次迭代时抛出ConcurrentModificationException异常
}
}

}