blocks|key|4350914|text|如果在这种情况下，与实际执行操作相比，迭代流或数组的成本更低，而不是只使用谓词并过滤时间是否已过。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4350915|final+long+end+=+System.nanoTime()+%2B+TimeUnit.SECONDS.toNanos(30L);
myDataStructure.stream()
++++.filter(e+->+System.nanoTime()+<=+end)
++++.forEach(e+->
++++{
++++++...
++++});|code-block|syntax|javascript|4350916|问题是，您是否需要知道哪些元素已被处理。使用上述方法，您必须检查特定元素是否在事后发生了副作用。|4350917|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

If iterating the stream or array in this case is cheap compared to actually executing the operation than just use a predicate and filter whether time is over or not.

<pre><code>final long end = System.nanoTime() + TimeUnit.SECONDS.toNanos(30L);
myDataStructure.stream()
 .filter(e -&gt; System.nanoTime() &lt;= end)
 .forEach(e -&gt;
 {
 ...
 });
</code></pre>

Question is if you need to know which elements have been processed or not. With the above you have to inspect whether a side effect took place for a specific element afterwards.

blocks|key|4351414|text|您可以利用.allMatch()是一个短路操作符的事实来终止流：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4351415|final+long+start+=+System.currentTimeMillis();
myDataStructure.stream()
++++.allMatch(e+->
++++{
++++++//+your+task+here
++++++++return+System.currentTimeMillis()+<=+start+%2B+30000;
++++});|code-block|syntax|javascript|4351416|entityMap^0|5|B|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

You can use the fact that <code>.allMatch()</code> is a short-circuiting operator to terminate the stream:

<pre><code>final long start = System.currentTimeMillis();
myDataStructure.stream()
 .allMatch(e -&gt;
 {
 // your task here
 return System.currentTimeMillis() &lt;= start + 30000;
 });
</code></pre>

blocks|key|4351458|text|我将为此创建一个自定义池，如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4351459|ForkJoinPool+forkJoinPool+=+new+ForkJoinPool(1);
++++try+{
++++++++forkJoinPool.submit(()+->
++++++++IntStream.range(1,+1_000_000).filter(x+->+x+>+2).boxed().collect(Collectors.toList()))
++++++++++++++++.get(30,+TimeUnit.MILLISECONDS);
++++}+catch+(TimeoutException+e)+{
++++++++//+job+not+done+in+your+interval
++++}|code-block|syntax|javascript|4351460|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I would create a custom pool for that, something like:

<pre><code>ForkJoinPool forkJoinPool = new ForkJoinPool(1);
 try {
 forkJoinPool.submit(() -&gt;
 IntStream.range(1, 1_000_000).filter(x -&gt; x &gt; 2).boxed().collect(Collectors.toList()))
 .get(30, TimeUnit.MILLISECONDS);
 } catch (TimeoutException e) {
 // job not done in your interval
 }
</code></pre>

blocks|key|4351022|text|就像OP下面的注释所说的那样，在Java+8中缺少takeWhile/dropWhile+(将在Java+9中添加)。没有任何理由试图通过异常或其他代码来实现逻辑，因为代码看起来非常丑陋，完全没有场景，即使它只是为了实践。我认为使用第三方库是一个好得多的解决方案，例如StreamEx|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|4351023|StreamEx(source).takeWhile(()+->+System.currentTimeMillis()+<=+start+%2B+30000)
++++++++++++++++.forEach(e+->+{+...+});|code-block|syntax|javascript|4351024|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/amaembo/streamex^0|3Q|8|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

As what the comments said under the OP, takeWhile/dropWhile are missed in Java 8 (will be added in Java 9). There is no any reason to try to implement the logic by exception or other codes because the code just looks so ugly and total nonscenes even it's just for practice. I think using 3rd party library is a much, much better solution, for example <a href="https://github.com/amaembo/streamex" rel="nofollow noreferrer">StreamEx</a>

<pre><code>StreamEx(source).takeWhile(() -&gt; System.currentTimeMillis() &lt;= start + 30000)
 .forEach(e -&gt; { ... });
</code></pre>

I want to loop over a huge array and do a complicated set of instructions that takes a long time. However, if more than 30 seconds have passed, I want it to give up.

ex.

<pre><code>final long start = System.currentTimeMillis();
myDataStructure.stream()
 .while(() -&gt; System.currentTimeMillis() &lt;= start + 30000)
 .forEach(e -&gt;
 {
 ...
 });
</code></pre>

I want to avoid just saying <code>return</code> inside the <code>forEach</code> call if a certain condition is met.

Java 8 Streams - Timeout?

Java

我想循环遍历一个巨大的数组，并执行一组复杂的指令，这需要很长时间。但是，如果超过30秒，我希望它放弃。例如。final long start = System.currentTimeMillis();myDataStructure.stream()    .while(() -> System.currentTimeM...

问Java 8 Streams -超时？
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