blocks|key|1350357|text|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1350358|在遍历迭代器时不使用iterator.hasNext()是明智的吗？|blockquote|1350359|1350360|1350361|嗯，不是。hasNext是使用迭代器进行迭代的标准方式。例如，这就是enhanced-for+statement在幕后为迭代器所做的事情。|offset|length|style|CODE|1350362|话虽如此，您的代码已经是特定于ListIterator的，因为您使用的是ListIterator.set+-所以此时您的第二个代码块实际上不会被编译。即使它成功了，它也不会工作，因为你仍然需要调用next()。不过，这将会起作用：|1350363|for+(ListIterator<?+super+T>+itr+=+list.listIterator();+itr.hasNext();+)+{
++++itr.next();
++++itr.set(obj);
}|code-block|syntax|javascript|1350364|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/specs/jls/se7/html/jls-14.html#jls-14.14.2^0|0|0|0|0|5|7|Y|M|0|0|10|G|2Q|6|0|0^^$0|@$1|2|3|-4|4|5|6|10|7|@]|8|@]|9|$]]|$1|A|3|B|4|C|6|11|7|@]|8|@]|9|$]]|$1|D|3|-4|4|5|6|12|7|@]|8|@]|9|$]]|$1|E|3|-4|4|5|6|13|7|@]|8|@]|9|$]]|$1|F|3|G|4|5|6|14|7|@$H|15|I|16|J|K]]|8|@$H|17|I|18|1|19]]|9|$]]|$1|L|3|M|4|5|6|1A|7|@$H|1B|I|1C|J|K]|$H|1D|I|1E|J|K]]|8|@]|9|$]]|$1|N|3|O|4|P|6|1F|7|@]|8|@]|9|$Q|R]]|$1|S|3|-4|4|5|6|1G|7|@]|8|@]|9|$]]]|T|$U|$4|V|W|X|9|$Y|Z]]]]

<blockquote>
 Is it advisable not to use iterator.hasNext() in looping over an iterator?
</blockquote>

Um, no. <code>hasNext</code> is the standard way you iterate with an iterator. That's what the <a href="http://docs.oracle.com/javase/specs/jls/se7/html/jls-14.html#jls-14.14.2" rel="noreferrer">enhanced-for statement</a> does behind the scenes for an iterable, for example.

Having said that, your code is already ListIterator-specific, as you're using <code>ListIterator.set</code> - so your second block of code won't actually compile at the moment. Even if it did, it wouldn't work, as you still need to call <code>next()</code>. This would work though:

<pre><code>for (ListIterator&lt;? super T&gt; itr = list.listIterator(); itr.hasNext(); ) {
 itr.next();
 itr.set(obj);
}
</code></pre>

blocks|key|593372|text|嗯，当NetBeans重构for-each循环以使用迭代器时，它们通过以下方式完成。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|593373|for-each：|593374|for+(T+object+:+list)+{
}|code-block|syntax|javascript|593375|迭代器模式：|593376|for+(Iterator<T>+it+=+list.iterator();+it.hasNext();)+{
++++T+object+=+it.next();
}|593377|我认为在迭代时对迭代器使用hasNext()是完全可以的。|593378|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|T|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

Well, when NetBeans refactor you for-each loop to use of iterators, they do it in following way.

for-each:

<pre><code>for (T object : list) {
}
</code></pre>

iterator pattern:

<pre><code>for (Iterator&lt;T&gt; it = list.iterator(); it.hasNext();) {
 T object = it.next();
}
</code></pre>

I think it is totally okay to use hasNext() on iterator while iterating.

blocks|key|593410|text|没有这样的建议不使用hasNext。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|593411|Iterator+API列表只有三个方法：add、remove和hasNext|593412|同样，从干净的代码来看，第二种方法看起来比第一种要好得多。|593413|entityMap^0|A|7|0|L|3|P|6|W|7|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|V|8|@]|D|@]|E|$]]|$1|J|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|K|$]]

There is no such recommendation not to use <code>hasNext</code>.

The Iterator API list has just three methods, <code>add</code>, <code>remove</code> and <code>hasNext</code>

Also from clean code the second approach looks far better then the first one.

blocks|key|1348607|text|使用迭代器时，应该始终调用hasNext()方法。否则，在调用NoSuchElementException+()方法时可能会遇到next。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1348608|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

When using an iterator, you should always call the hasNext() method. Otherwise, you may run into a NoSuchElementException when calling the next() method.

blocks|key|593479|text|当然，您应该使用hasNext()，但仅用于迭代集合，而不是填充集合。要填充集合，请处理集合本身，而不是它的迭代器，并使用@JMelnik描述的for循环从集合中读取。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|593480|填充集合|BOLD|593481|Collection<MyObject>+list+=+...;
while+(something)+{
++++list.add(myObject);
}|code-block|syntax|javascript|593482|读取集合|593483|for+(MyObject+myObject+:+list)+{
++++...
}|593484|entityMap^0|8|9|20|3|0|0|4|0|0|0|4|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@$9|U|A|V|B|C]|$9|W|A|X|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Y|8|@$9|Z|A|10|B|H]]|D|@]|E|$]]|$1|I|3|J|5|K|7|11|8|@]|D|@]|E|$L|M]]|$1|N|3|O|5|6|7|12|8|@$9|13|A|14|B|H]]|D|@]|E|$]]|$1|P|3|Q|5|K|7|15|8|@]|D|@]|E|$L|M]]|$1|R|3|-4|5|6|7|16|8|@]|D|@]|E|$]]]|S|$]]

Of course, you should use <code>hasNext()</code>, but only for iterating over a collection, not for populating the collection. To fill the collection, work on the collection itself, not on it's iterator and to read from the collection use the <code>for</code> loop as described by @JMelnik.

Fill the collection

<pre class="lang-java prettyprint-override"><code>Collection&lt;MyObject&gt; list = ...;
while (something) {
 list.add(myObject);
}
</code></pre>

Read the collection

<pre><code>for (MyObject myObject : list) {
 ...
}
</code></pre>

Is it advisable not to use iterator.hasNext() in looping over an iterator?

For example I would like to set value obj to each element of a list. I could use the following code or make it more readable by using hasNext() in a loop.

<pre><code>int size = list.size();
ListIterator&lt;? super T&gt; itr = list.listIterator();
for (int i=0; i&lt;size; i++) {
 itr.next();
 itr.set(obj);
}
</code></pre>

Instead of these lines I could write my code like the following.

<pre><code>for (ListIterator&lt;? super T&gt; itr = list.listIterator(); itr.hasNext(); ) {
 itr.next();
 itr.set(obj);
}
</code></pre>

Should we avoid hasNext() call in an Iterator?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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在遍历迭代器时不使用iterator.hasNext()是明智的吗？例如，我想为列表中的每个元素设置值obj。我可以使用以下代码，也可以通过在循环中使用hasNext()使其更具可读性。int size = list.size();ListIterator<? super T> itr = list.listItera...

问我们应该避免在迭代器中调用hasNext()吗？
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问我们应该避免在迭代器中调用hasNext()吗？EN