blocks|key|1443950|text|我假设您希望清除BehaviorSubject+(因为否则不会调用onComplete+)。这是不支持的，但是您可以通过拥有一个被使用者忽略的当前值来实现类似的效果：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1443951|public+static+final+Object+EMPTY+=+new+Object();

BehaviorSubject<Object>+subject+=+BehaviorSubject.createDefault(EMPTY);

Observable<YourType>+obs+=+subject.filter(v+->+v+!=+EMPTY).cast(YourType.class);

obs.subscribe(System.out::println);

//+send+normal+data
subject.onNext(1);
subject.onNext(2);

//+clear+the+subject
subject.onNext(EMPTY);

//+this+should+not+print+anything
obs.subscribe(System.out::println);|code-block|syntax|javascript|1443952|entityMap^0|8|F|X|A|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

I assume you want to clear the <code>BehaviorSubject</code> (because otherwise don't call <code>onComplete</code> on it). That is not supported but you can achieve a similar effect by having a current value that is ignored by consumers:

<pre><code>public static final Object EMPTY = new Object();

BehaviorSubject&lt;Object&gt; subject = BehaviorSubject.createDefault(EMPTY);

Observable&lt;YourType&gt; obs = subject.filter(v -&gt; v != EMPTY).cast(YourType.class);

obs.subscribe(System.out::println);

// send normal data
subject.onNext(1);
subject.onNext(2);

// clear the subject
subject.onNext(EMPTY);

// this should not print anything
obs.subscribe(System.out::println);
</code></pre>

blocks|key|709308|text|切换可观测开关值的另一种方法是使用switchMap()在实际可观测值和空值之间切换。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|709309|让我们假设您有一个manager对象，并且它有一个可观察的、显示其状态的对象。然后,|709310|subjectObservable+=+manager.getStateObservable()
++.switchMap(+state+->+state+==+ON+?+subject+:+Observable.never()+);|code-block|syntax|javascript|709311|只有在manager处于ON状态时才会发出值。|709312|entityMap^0|H|B|0|0|0|3|7|C|2|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|T|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|U|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|V|8|@$9|W|A|X|B|C]|$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|O|3|-4|5|6|7|10|8|@]|D|@]|E|$]]]|P|$]]

Another method of switching the value of an observable on and off is to use <code>switchMap()</code> to flip between the actual observable and an empty one.

Let's assume you have a manager object, and it has a observable that shows its state. Then,

<pre><code>subjectObservable = manager.getStateObservable()
 .switchMap( state -&gt; state == ON ? subject : Observable.never() );
</code></pre>

will only emit values while the <code>manager</code> is in the <code>ON</code> state.

blocks|key|1444032|text|只需像这样使用setTimeout：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1444033|setOtpoint(value)+{

++++this._setOption.next(value);

++++//+Clear+BehaviorSubject+after+emit+value

++++setTimeout(()+=>+{
++++++this._setOption.next(null);
++++},+100);

++}|code-block|syntax|javascript|1444034|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|$]]

Just use setTimeout like this:

<pre><code>setOtpoint(value) {

 this._setOption.next(value);

 // Clear BehaviorSubject after emit value

 setTimeout(() =&gt; {
 this._setOption.next(null);
 }, 100);

 }
</code></pre>

blocks|key|709318|text|我想出了一个更好的解决办法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|709319|subject.skiplast(1)|code-block|syntax|javascript|709320|它可以工作于清洁，这是由于BehaviorSubject“行为”而保留的流中的最后一个位置。|offset|length|style|BOLD|CODE|709321|entityMap^0|0|0|6|2|D|F|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Q|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|R|8|@$I|S|J|T|K|L]|$I|U|J|V|K|M]]|9|@]|A|$]]|$1|N|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|O|$]]

I find out a better solution for some cases and is: 

<pre><code>subject.skiplast(1)
</code></pre>

it can work to clean the last position on stream that is being retained because of the <code>BehaviorSubject</code> "behavior"

blocks|key|709339|text|@akarnokd的一个问题是，.cast阻止YourType成为接口或泛型类型(如List<String>+)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|709340|另一种选择是对布尔字段进行筛选，您可以打开或关闭该字段。|709341|++++private+BehaviorSubject<PandoraApp>+subject+=+BehaviorSubject.create();
++++private+boolean+enabled+=+true;

++++Observable<PandoraApp>+observable+=+subject.filter(v+->+enabled);|code-block|syntax|javascript|709342|如果在不同线程上调用方法，则可以使用AtomicBoolean作为筛选标志。|709343|entityMap^0|16|C|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|T|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|U|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|V|8|@]|D|@]|E|$]]|$1|O|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|P|$]]

A problem with @akarnokd's answer is that the .cast prevents YourType from being an interface or a generic type such as <code>List&lt;String&gt;</code>.
Another option is to filter on a boolean field that you can switch on and off.
<pre class="lang-java prettyprint-override"><code> private BehaviorSubject&lt;PandoraApp&gt; subject = BehaviorSubject.create();
 private boolean enabled = true;

 Observable&lt;PandoraApp&gt; observable = subject.filter(v -&gt; enabled);
</code></pre>
If methods are being called on different threads you can use AtomicBoolean for the filter flag.

blocks|key|709345|text|这是我的库：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|709346|implementation+"com.github.kolyall:rxjava2-empty:1.0.36"|offset|length|style|CODE|709347|示例：|709348|private+val+myBehaviorSubject+=+BehaviorSubjectOptional.createOptional<MyItem?>()

errorBehaviorSubject.toObservable()
.subscribe{+item->+Log.d("onNext1",+"item+=+$item")}

var+item:MyItem?+=+MyItem()
myBehaviorSubject.onNextOptional(item)

//For+reset:
myBehaviorSubject.clear()
//OR
item+=+null
myBehaviorSubject.onNextOptional(item)


errorBehaviorSubject.toObservable()
.subscribe{+item->+Log.d("onNext2",+"item+=+$item")}|code-block|syntax|javascript|709349|entityMap^0|0|0|1K|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@$D|S|E|T|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|U|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|V|8|@]|9|@]|A|$M|N]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

Here is my lib for this:

<code>implementation "com.github.kolyall:rxjava2-empty:1.0.36"</code>

Example:

<pre><code>
private val myBehaviorSubject = BehaviorSubjectOptional.createOptional&lt;MyItem?&gt;()

errorBehaviorSubject.toObservable()
.subscribe{ item-&gt; Log.d("onNext1", "item = $item")}

var item:MyItem? = MyItem()
myBehaviorSubject.onNextOptional(item)

//For reset:
myBehaviorSubject.clear()
//OR
item = null
myBehaviorSubject.onNextOptional(item)


errorBehaviorSubject.toObservable()
.subscribe{ item-&gt; Log.d("onNext2", "item = $item")}
</code></pre>

I have a <code>BehaviorSubject</code> that I would like to reset - by that I mean I want the latest value to not be available, just as if it was just created.

I don't seem to see an API to do this but I suppose there is another way to achieve the same result?

My desired behavior is that I need to emit events, and I'd like subscribers to get the latest event when they subscribe - if a particular manager is in a 'started' state. But when this manager is 'stopped' the latest event should not be available (just like if it was never started in the first place).

How to reset a BehaviorSubject

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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我有一个BehaviorSubject，我想要重置-我的意思是，我希望最新的价值不可用，就像它是刚刚创建的。我似乎没有看到一个API来做到这一点，但我想还有另一种方法可以实现同样的结果吗？我想要的行为是，我需要发出事件，如果某个特定的管理器处于“已启动”状态，我希望订阅者在订阅时获得最新的事件。但是，当这个管理器被“停止”时，最新的事件就不应该可用了(就像它从一开始就没有启动一样)。

问如何重置BehaviorSubject
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回答 6

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