再次踩bug:遍历删除list(java.util.ConcurrentModificationException)

List<Long> list = new ArrayList<Long>();
for(Long l : list){
    if(l == 5){
        list.remove(l);
    }
}    
for(int i=0; i<list.size(); i++){
    if(l == 5){
       list.remove(l);
    }    
}

List<Long> list = new ArrayList<Long>();
Iterator<Long> it = list.iterator();
while(it.hasNext){
    if(it.next() == 5){
        it.remove();//注意此处不能用list.remove(it.next());
    }
}