[英]Removing an item from a list in Java
I've scoured this site (as well as the web) and for some reason cannot find an answer that works. 我已经搜索了该网站(以及网络),并且由于某种原因找不到有效的答案。 Either I get an index out of bounds error, or the next part of my code won't execute.
我得到一个超出范围的索引错误,或者我的代码的下一部分将无法执行。 All I am trying to do is remove a item from a list in Java using an iterator.
我要做的就是使用迭代器从Java列表中删除一个项目。 Here is my code:
这是我的代码:
public boolean remove(T item) {
while (bag.iterator().hasNext()) {
T i = bag.iterator().next();
if (i.equals(item)) {
bag.iterator().remove();
return true;
}
}
return false;
}
My iterator inherits from my "Bag" class obviously, but here it is as well: 我的迭代器显然是从“ Bag”类继承的,但在这里也是如此:
public Iterator<T> iterator() {
return new Iterator<T>() {
private int current = 0;
public boolean hasNext() {
return current < size;
}
public T next() {
return data[current++];
}
public void remove() {
for (int i=current-1; i<size-1; i++)
data[i] = data[i+1];
size--;
}
};
}
Any help is much appreciated, thanks guys!! 非常感谢任何帮助,谢谢大家!!
Clayton 克莱顿
Every time you call bag.iterator()
, you get a new Iterator
object, not the same one you had before. 每次调用
bag.iterator()
,都会得到一个新的Iterator
对象,而不是以前的对象。 You should get the iterator once, then use it through your loop: 您应该获取一次迭代器,然后在循环中使用它:
public boolean remove(T item) {
Iterator<T> iter = bag.iterator();
while (iter.hasNext()) {
T i = iter.next();
if (i.equals(item)) {
iter.remove();
return true;
}
}
return false;
}
Your code has another issue: if you call remove()
on your iterator before you call next()
, your code will try to access data[-1]
. 您的代码还有另一个问题:如果在调用
next()
之前在迭代器上调用remove()
next()
,则代码将尝试访问data[-1]
。 You might want to put some protection code around that such as: 您可能需要在其中添加一些保护代码,例如:
public void remove() {
if(current > 0) {
for (int i=current-1; i<size-1; i++)
data[i] = data[i+1];
size--;
}
}
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