未使用订阅结果 [英] The result of subscribe is not used

问题描述

我今天已经升级到Android Studio 3.1，它似乎增加了一些棉绒检查.这些棉绒检查之一是针对一次未存储在变量中的RxJava2 subscribe()调用.例如，从我的房间数据库中获取所有玩家的列表:

I've upgraded to Android Studio 3.1 today, which seems to have added a few more lint checks. One of these lint checks is for one-shot RxJava2 subscribe() calls that are not stored in a variable. For example, getting a list of all players from my Room database:

Single.just(db)
            .subscribeOn(Schedulers.io())
            .subscribe(db -> db.playerDao().getAll());

结果会出现一个大的黄色方块，并显示以下提示:

Results in a big yellow block and this tooltip:

未使用subscribe的结果

像这样的一次性Rx呼叫的最佳做法是什么?我应该完整保留Disposable和dispose()吗?还是我应该@SuppressLint继续前进?

What is the best practice for one-shot Rx calls like this? Should I keep hold of the Disposable and dispose() on complete? Or should I just @SuppressLint and move on?

这似乎只影响RxJava2(io.reactivex)，RxJava(rx)没有此绒毛.

This only seems to affect RxJava2 (io.reactivex), RxJava (rx) does not have this lint.

推荐答案

IDE不知道您的订阅在不被处置时可能产生什么潜在影响，因此将其视为潜在的不安全因素.例如，您的Single可能包含一个网络调用，如果您的Activity在执行过程中被放弃，则可能导致内存泄漏.

The IDE does not know what potential effects your subscription can have when it's not disposed, so it treats it as potentially unsafe. For example, your Single may contain a network call, which could cause a memory leak if your Activity is abandoned during its execution.

管理大量Disposable的便捷方法是使用

A convenient way to manage a large amount of Disposables is to use a CompositeDisposable; just create a new CompositeDisposable instance variable in your enclosing class, then add all your Disposables to the CompositeDisposable (with RxKotlin you can just append addTo(compositeDisposable) to all of your Disposables). Finally, when you're done with your instance, call compositeDisposable.dispose().

这将消除棉绒警告，并确保正确管理您的Disposables.

This will get rid of the lint warnings, and ensure your Disposables are managed properly.

在这种情况下，代码如下:

In this case, the code would look like:

CompositeDisposable compositeDisposable = new CompositeDisposable();

Disposable disposable = Single.just(db)
        .subscribeOn(Schedulers.io())
        .subscribe(db -> db.get(1)));

compositeDisposable.add(disposable); //IDE is satisfied that the Disposable is being managed. 
disposable.addTo(compositeDisposable); //Alternatively, use this RxKotlin extension function.


compositeDisposable.dispose(); //Placed wherever we'd like to dispose our Disposables (i.e. in onDestroy()).

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