blocks|key|1050051|text|您可以使用StreamController。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1050052|在这里，我翻译了第一个C#实例+for+BlockingCollection|style|CODE|1050053|using+System;
using+System.Collections.Concurrent;
using+System.Threading;
using+System.Threading.Tasks;

class+BlockingCollectionDemo
{
++++static+async+Task+Main()
++++{
++++++++await+AddTakeDemo.BC_AddTakeCompleteAdding();
++++}
}
class+AddTakeDemo
{
++++//+Demonstrates:
++++//++++++BlockingCollection<T>.Add()
++++//++++++BlockingCollection<T>.Take()
++++//++++++BlockingCollection<T>.CompleteAdding()
++++public+static+async+Task+BC_AddTakeCompleteAdding()
++++{
++++++++using+(BlockingCollection<int>+bc+=+new+BlockingCollection<int>())
++++++++{
++++++++++++//+Spin+up+a+Task+to+populate+the+BlockingCollection
++++++++++++Task+t1+=+Task.Run(()+=>
++++++++++++{
++++++++++++++++bc.Add(1);
++++++++++++++++bc.Add(2);
++++++++++++++++bc.Add(3);
++++++++++++++++bc.CompleteAdding();
++++++++++++});

++++++++++++//+Spin+up+a+Task+to+consume+the+BlockingCollection
++++++++++++Task+t2+=+Task.Run(()+=>
++++++++++++{
++++++++++++++++try
++++++++++++++++{
++++++++++++++++++++//+Consume+consume+the+BlockingCollection
++++++++++++++++++++while+(true)+Console.WriteLine(bc.Take());
++++++++++++++++}
++++++++++++++++catch+(InvalidOperationException)
++++++++++++++++{
++++++++++++++++++++//+An+InvalidOperationException+means+that+Take()+was+called+on+a+completed+collection
++++++++++++++++++++Console.WriteLine("That's+All!");
++++++++++++++++}
++++++++++++});

++++++++++++await+Task.WhenAll(t1,+t2);
++++++++}
++++}
}|code-block|syntax|javascript|1050054|使用StreamController代替BlockingCollection，使用Future代替Task。|1050055|import+'dart:async';

Future<void>+main()+async+{
++await+addTakeCompleteAdding();
}

//+Demonstrates:
//++++++StreamController<T>.add()
//++++++StreamController<T>.stream
//++++++StreamController<T>.close()
Future<void>+addTakeCompleteAdding()+async+{
++StreamController<int>+bc+=+StreamController<int>();

++//+Spin+up+a+Future+to+populate+the+StreamController
++Future<void>+t1+=+Future(()+{
++++bc.add(1);
++++bc.add(2);
++++bc.add(3);
++++bc.close();
++});

++//+Spin+up+a+Future+to+consume+the+StreamController
++Future<void>+t2+=+Future(()+async+{
++++//+Consume+consume+the+StreamController
++++await+for+(final+element+in+bc.stream)+{
++++++print(element);
++++}
++++//+Exits+the+loop+when+the+stream+is+completed/closed
++++print("That's+All!");
++});

++await+Future.wait([t1,+t2]);
}|1050056|也就是说，StreamController与BlockingCollection略有不同，因为它不是队列。默认情况下，dart中的Stream只能有一个订阅，除非创建广播流。Stream更像是C#中的异步枚举。|1050057|如果确实需要队列数据结构，可以使用异步包，它有一个StreamQueue类，可以用来包装来自StreamController的流。|1050058|下面是为使用StreamQueue而修改的上述代码|1050059|import+'dart:async';
import+'package:async/async.dart';

Future<void>+main()+async+{
++await+addTakeCompleteAdding();
}

//+Demonstrates:
//++++++StreamController<T>.add()
//++++++StreamController<T>.stream
//++++++StreamController<T>.close()
//++++++StreamQueue<T>.next
Future<void>+addTakeCompleteAdding()+async+{
++StreamController<int>+bc+=+StreamController<int>();
++StreamQueue<int>+queue+=+StreamQueue<int>(bc.stream);

++//+Spin+up+a+Future+to+populate+the+StreamController
++Future<void>+t1+=+Future(()+{
++++bc.add(1);
++++bc.add(2);
++++bc.add(3);
++++bc.close();
++});

++//+Spin+up+a+Future+to+consume+the+StreamQueue
++Future<void>+t2+=+Future(()+async+{
++++try+{
++++++while+(true)+{
++++++++//+Consume+consume+the+StreamQueue
++++++++print(await+queue.next);
++++++}
++++}+on+StateError+catch+(e)+{
++++++//+A+StateError+means+that+next+was+called+on+a+completed+collection
++++++print("That's+all!");
++++}
++});

++await+Future.wait([t1,+t2]);
}|1050060|entityMap|0|LINK|mutability|MUTABLE|url|https://api.dart.dev/stable/2.16.1/dart-async/StreamController-class.html|1|https://learn.microsoft.com/en-us/dotnet/api/system.collections.concurrent.blockingcollection-1?view=net-6.0#examples|2|https://pub.dev/packages/async|3|https://pub.dev/documentation/async/latest/async/StreamQueue-class.html^0|5|G|0|0|K|I|B|4|1|0|0|2|G|K|I|15|6|1D|4|0|0|5|G|M|I|1T|6|2F|6|0|P|B|1A|G|H|3|2|0|6|B|3|0|0^^$0|@$1|2|3|4|5|6|7|1C|8|@]|9|@$A|1D|B|1E|1|1F]]|C|$]]|$1|D|3|E|5|6|7|1G|8|@$A|1H|B|1I|F|G]]|9|@$A|1J|B|1K|1|1L]]|C|$]]|$1|H|3|I|5|J|7|1M|8|@]|9|@]|C|$K|L]]|$1|M|3|N|5|6|7|1N|8|@$A|1O|B|1P|F|G]|$A|1Q|B|1R|F|G]|$A|1S|B|1T|F|G]|$A|1U|B|1V|F|G]]|9|@]|C|$]]|$1|O|3|P|5|J|7|1W|8|@]|9|@]|C|$K|L]]|$1|Q|3|R|5|6|7|1X|8|@$A|1Y|B|1Z|F|G]|$A|20|B|21|F|G]|$A|22|B|23|F|G]|$A|24|B|25|F|G]]|9|@]|C|$]]|$1|S|3|T|5|6|7|26|8|@$A|27|B|28|F|G]|$A|29|B|2A|F|G]]|9|@$A|2B|B|2C|1|2D]]|C|$]]|$1|U|3|V|5|6|7|2E|8|@]|9|@$A|2F|B|2G|1|2H]]|C|$]]|$1|W|3|X|5|J|7|2I|8|@]|9|@]|C|$K|L]]|$1|Y|3|-4|5|6|7|2J|8|@]|9|@]|C|$]]]|Z|$10|$5|11|12|13|C|$14|15]]|16|$5|11|12|13|C|$14|17]]|18|$5|11|12|13|C|$14|19]]|1A|$5|11|12|13|C|$14|1B]]]]

You can use a <a href="https://api.dart.dev/stable/2.16.1/dart-async/StreamController-class.html" rel="nofollow noreferrer">StreamController</a>.
Here I translated the first <a href="https://learn.microsoft.com/en-us/dotnet/api/system.collections.concurrent.blockingcollection-1?view=net-6.0#examples" rel="nofollow noreferrer">C# example</a> for <code>BlockingCollection</code>
<pre class="lang-cs prettyprint-override"><code>using System;
using System.Collections.Concurrent;
using System.Threading;
using System.Threading.Tasks;

class BlockingCollectionDemo
{
 static async Task Main()
 {
 await AddTakeDemo.BC_AddTakeCompleteAdding();
 }
}
class AddTakeDemo
{
 // Demonstrates:
 // BlockingCollection&lt;T&gt;.Add()
 // BlockingCollection&lt;T&gt;.Take()
 // BlockingCollection&lt;T&gt;.CompleteAdding()
 public static async Task BC_AddTakeCompleteAdding()
 {
 using (BlockingCollection&lt;int&gt; bc = new BlockingCollection&lt;int&gt;())
 {
 // Spin up a Task to populate the BlockingCollection
 Task t1 = Task.Run(() =&gt;
 {
 bc.Add(1);
 bc.Add(2);
 bc.Add(3);
 bc.CompleteAdding();
 });

 // Spin up a Task to consume the BlockingCollection
 Task t2 = Task.Run(() =&gt;
 {
 try
 {
 // Consume consume the BlockingCollection
 while (true) Console.WriteLine(bc.Take());
 }
 catch (InvalidOperationException)
 {
 // An InvalidOperationException means that Take() was called on a completed collection
 Console.WriteLine(&quot;That's All!&quot;);
 }
 });

 await Task.WhenAll(t1, t2);
 }
 }
}
</code></pre>
to dart using a <code>StreamController</code> instead of <code>BlockingCollection</code>, and <code>Future</code> instead of <code>Task</code>.
<pre class="lang-dart prettyprint-override"><code>import 'dart:async';

Future&lt;void&gt; main() async {
 await addTakeCompleteAdding();
}

// Demonstrates:
// StreamController&lt;T&gt;.add()
// StreamController&lt;T&gt;.stream
// StreamController&lt;T&gt;.close()
Future&lt;void&gt; addTakeCompleteAdding() async {
 StreamController&lt;int&gt; bc = StreamController&lt;int&gt;();

 // Spin up a Future to populate the StreamController
 Future&lt;void&gt; t1 = Future(() {
 bc.add(1);
 bc.add(2);
 bc.add(3);
 bc.close();
 });

 // Spin up a Future to consume the StreamController
 Future&lt;void&gt; t2 = Future(() async {
 // Consume consume the StreamController
 await for (final element in bc.stream) {
 print(element);
 }
 // Exits the loop when the stream is completed/closed
 print(&quot;That's All!&quot;);
 });

 await Future.wait([t1, t2]);
}
</code></pre>
That said, the <code>StreamController</code> differs a bit from <code>BlockingCollection</code> in that it is not a queue. A <code>Stream</code> in dart by default, can only have one subscription, unless you create a broadcast stream. <code>Stream</code> is more like an async enumerable in C#.
If you really need a queue data structure you can use the <a href="https://pub.dev/packages/async" rel="nofollow noreferrer">async package</a>, which has a <code>StreamQueue</code> class that you can use to wrap the stream from the <code>StreamController</code>.
Here is the above code modified to use a <a href="https://pub.dev/documentation/async/latest/async/StreamQueue-class.html" rel="nofollow noreferrer">StreamQueue</a>:
<pre class="lang-dart prettyprint-override"><code>import 'dart:async';
import 'package:async/async.dart';

Future&lt;void&gt; main() async {
 await addTakeCompleteAdding();
}

// Demonstrates:
// StreamController&lt;T&gt;.add()
// StreamController&lt;T&gt;.stream
// StreamController&lt;T&gt;.close()
// StreamQueue&lt;T&gt;.next
Future&lt;void&gt; addTakeCompleteAdding() async {
 StreamController&lt;int&gt; bc = StreamController&lt;int&gt;();
 StreamQueue&lt;int&gt; queue = StreamQueue&lt;int&gt;(bc.stream);

 // Spin up a Future to populate the StreamController
 Future&lt;void&gt; t1 = Future(() {
 bc.add(1);
 bc.add(2);
 bc.add(3);
 bc.close();
 });

 // Spin up a Future to consume the StreamQueue
 Future&lt;void&gt; t2 = Future(() async {
 try {
 while (true) {
 // Consume consume the StreamQueue
 print(await queue.next);
 }
 } on StateError catch (e) {
 // A StateError means that next was called on a completed collection
 print(&quot;That's all!&quot;);
 }
 });

 await Future.wait([t1, t2]);
}
</code></pre>

blocks|key|1065582|text|您还可以根据期货而不是流编写自己的队列：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1065583|import+"dart:async"+show+Completer;
import+"dart:collection"+show+Queue;

abstract+class+BlockingQueue<T>+{
++factory+BlockingQueue()+=+_BlockingQueue;
++Future<T>+removeNext();
++void+add(T+value);
}

class+_BlockingQueue<T>+implements+BlockingQueue<T>+{
++final+Queue<T>+_writes+=+Queue();
++final+Queue<Completer<T>>+_reads+=+Queue();
++Future<T>+removeNext()+{
++++if+(_writes.isNotEmpty)+return+Future.value(_writes.removeFirst());
++++var+completer+=+Completer<T>();
++++_reads.add(completer);
++++return+completer.future;
++}
++void+add(T+value)+{
++++if+(_reads.isNotEmpty)+{
++++++_reads.removeFirst().complete(value);
++++}+else+{
++++++_writes.add(value);
++++}
++}
}|code-block|syntax|javascript|1065584|您还可以考虑一个双阻塞队列，如果还没有人接受该值，add方法也会“阻塞”。这也没那么难。|offset|length|style|CODE|1065585|import+"dart:async"+show+Completer;
import+"dart:collection"+show+Queue;

abstract+class+BlockingQueue<T>+{
++factory+BlockingQueue()+=+_BlockingQueue;
++Future<T>+removeNext();
++Future<void>+add(T+value);
}

class+_BlockingQueue<T>+implements+BlockingQueue<T>+{
++final+Queue<T>+_writes+=+Queue();
++final+Queue<Completer<T>>+_completers+=+Queue();
++Future<T>+removeNext()+{

++++if+(_writes.isNotEmpty)+{
++++++assert(_completers.isNotEmpty);
++++++var+completer+=+_completers.removeFirst();
++++++completer.complete(_writes.removeFirst());
++++++return+completer.future;
++++}
++++var+completer+=+Completer<T>();
++++_completers.add(completer);
++++return+completer.future;
++}
++Future<void>+add(T+value)+{
++++if+(_writes.isEmpty+&&+_completers.isNotEmpty)+{
++++++var+completer+=+_completers.removeFirst();
++++++completer.complete(value);
++++++return+completer.future;
++++}
++++var+completer+=+Completer<T>();
++++_completers.add(completer);
++++_writes.add(value);
++++return+completer.future;
++}
}|1065586|也就是说，如果您想使用for+(...+in+...)-like循环，那么您可能需要使用Stream并使用await+for+(...+in+theStream)。|1065587|entityMap^0|0|0|P|3|0|0|B|G|18|6|1H|S|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@$I|V|J|W|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|Y|8|@$I|Z|J|10|K|L]|$I|11|J|12|K|L]|$I|13|J|14|K|L]]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|R|$]]

You can also write your own queue, based on futures instead of a stream:
<pre class="lang-dart prettyprint-override"><code>import &quot;dart:async&quot; show Completer;
import &quot;dart:collection&quot; show Queue;

abstract class BlockingQueue&lt;T&gt; {
 factory BlockingQueue() = _BlockingQueue;
 Future&lt;T&gt; removeNext();
 void add(T value);
}

class _BlockingQueue&lt;T&gt; implements BlockingQueue&lt;T&gt; {
 final Queue&lt;T&gt; _writes = Queue();
 final Queue&lt;Completer&lt;T&gt;&gt; _reads = Queue();
 Future&lt;T&gt; removeNext() {
 if (_writes.isNotEmpty) return Future.value(_writes.removeFirst());
 var completer = Completer&lt;T&gt;();
 _reads.add(completer);
 return completer.future;
 }
 void add(T value) {
 if (_reads.isNotEmpty) {
 _reads.removeFirst().complete(value);
 } else {
 _writes.add(value);
 }
 }
}
</code></pre>
You can also consider a double-blocking queue, where the <code>add</code> method also &quot;blocks&quot; if there is no-one to accept the value yet. It's not even that hard,.
<pre class="lang-dart prettyprint-override"><code>import &quot;dart:async&quot; show Completer;
import &quot;dart:collection&quot; show Queue;

abstract class BlockingQueue&lt;T&gt; {
 factory BlockingQueue() = _BlockingQueue;
 Future&lt;T&gt; removeNext();
 Future&lt;void&gt; add(T value);
}

class _BlockingQueue&lt;T&gt; implements BlockingQueue&lt;T&gt; {
 final Queue&lt;T&gt; _writes = Queue();
 final Queue&lt;Completer&lt;T&gt;&gt; _completers = Queue();
 Future&lt;T&gt; removeNext() {

 if (_writes.isNotEmpty) {
 assert(_completers.isNotEmpty);
 var completer = _completers.removeFirst();
 completer.complete(_writes.removeFirst());
 return completer.future;
 }
 var completer = Completer&lt;T&gt;();
 _completers.add(completer);
 return completer.future;
 }
 Future&lt;void&gt; add(T value) {
 if (_writes.isEmpty &amp;&amp; _completers.isNotEmpty) {
 var completer = _completers.removeFirst();
 completer.complete(value);
 return completer.future;
 }
 var completer = Completer&lt;T&gt;();
 _completers.add(completer);
 _writes.add(value);
 return completer.future;
 }
}
</code></pre>
That said, if you want to use a <code>for (... in ...)</code>-like loop, you probably do want to go with a <code>Stream</code> and use <code>await for (... in theStream)</code>.

I'm currently migrating an App's logic code from C# to Dart and I'm looking for a similiar collection type in Dart to C#s <a href="https://learn.microsoft.com/en-us/dotnet/api/system.collections.concurrent.blockingcollection-1?view=net-6.0" rel="nofollow noreferrer">BlockingCollection</a>. I basically want a queue where i can iterate infinitely. If the queue is empty it just waits until a new element is added.
Is that possible in Dart?
Best

Dart equivalent of BlockingCollection

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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我目前正在将应用程序的逻辑代码从C#迁移到Dart，我正在寻找Dart中类似的集合类型到C#s 。我基本上想要一个队列，在那里我可以无限迭代。如果队列为空，则只需等待添加新元素。这在达特有可能吗？最好的

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