如何从ArrayList中删除元素? [英] How to remove element from ArrayList?
问题描述
我已经加入数据转换成的ArrayList
现在要更新列表中,从它删除某些内容。
I have added data into ArrayList
and now want to update that list be deleting some element from it.
我在的ArrayList
类型 CartEntry
元素类似1,2,3,4。
I have element something like 1,2,3,4 in ArrayList
of type CartEntry
.
code:
ArrayList<CartEntry> items = new ArrayList<CartEntry>();
public void remove(int pId)
{
System.out.println(items.size());
for(CartEntry ce : items)
{
if(ce.getpId() == pId)
{
items.remove(ce);
//System.out.println(items.get(1));
}
}
items.add(new CartEntry(pId));
}
CartEntry code:
CartEntry Code :
public long getpId() {
return pId;
}
构造器:
public CartEntry(long pId) {
super();
this.pId = pId;
}
当我尝试这个code它给了我一个错误:
when I am trying this code it gives me an error:
java.util.ConcurrentModificationException
at java.util.ArrayList$Itr.checkForComodification(Unknown Source)
at java.util.ArrayList$Itr.next(Unknown Source)
下面PID是指定该项目的参数应该从项目中删除。
假设我想删除有2个数据,那么会有什么我有什么关系?项目
Here pId is the argument that specify that item should be deleted from items. Suppose I want to delete item that have 2 data then what will I have to do ?
推荐答案
您所面临的 ConcurrentModificationException的
,因为你是在同一个名单上做两个操作
在一个时间。即循环和除去同一时间。
You are facing ConcurrentModificationException
because you are doing two operations on the same list
at a time. i.e looping and removing same time.
中序,以避免这种情况下使用Iterator,它保证你安全地从列表中删除的元素。
Inorder to avoid this situation use Iterator,which guarantees you to remove the element from list safely .
一个简单的例子看起来像
A simple example looks like
Iterator<CartEntry> it = list.iterator();
while (it.hasNext()) {
if (it.next().getpId() == pId) {
it.remove();
break;
}
}
这篇关于如何从ArrayList中删除元素?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!