我正在尝试将几个可观察对象链接在一起,并根据已执行的可观察对象执行一些操作。但我面临着奇怪的行为。
class MainActivity : AppCompatActivity() {
val TAG: String = MainActivity::class.java.name
private lateinit var clicker: TextView
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
clicker = findViewById(R.id.clicker) as TextView
clicker.setOnClickListener {
val i = AtomicInteger()
getFirstObservable()
.subscribeOn(Schedulers.computation())
.observeOn(AndroidSchedulers.mainThread())
.doOnNext {
showMessage(i, it)
}
.flatMap { getSecondObservable() }
.doOnNext {
showMessage(i, it)
}
.flatMap { getThirdObservable() }
.doOnNext {
showMessage(i, it)
}
.subscribe()
}
}
fun getFirstObservable(): Observable<String> {
return Observable.fromCallable {
Thread.sleep(2000)
"Hello"
}
}
fun getSecondObservable(): Observable<Int> {
return Observable.fromCallable {
Thread.sleep(2000)
3
}
}
fun getThirdObservable(): Observable<String> {
return Observable.fromCallable {
Thread.sleep(2000)
"World!"
}
}
fun showMessage(i: AtomicInteger, obj: Any) {
val msg = "Message #${i.incrementAndGet()}: from ${Thread.currentThread().name}: $obj"
Log.e(TAG, msg)
clicker.text = msg
Toast.makeText(this, msg, Toast.LENGTH_SHORT).show()
}
}
在此示例中,日志将每 2 秒显示一次,但视图的所有更改都将在最后一个 observable 完成时完成。
12-04 01:11:30.465 19207-19207/com.googlevsky.rxtest E/com.googlevsky.rxtest.MainActivity: Message #1: from main: Hello
12-04 01:11:32.473 19207-19207/com.googlevsky.rxtest E/com.googlevsky.rxtest.MainActivity: Message #2: from main: 3
12-04 01:11:34.479 19207-19207/com.googlevsky.rxtest E/com.googlevsky.rxtest.MainActivity: Message #3: from main: World!
我认为这是 AndroidScheduler.mainThread() 的行为,因为当我删除这一行并用这样的视图包装更改时
Handler(Looper.getMainLooper()).post {
clicker.text = msg
Toast.makeText(this, msg, Toast.LENGTH_SHORT).show()
}
行为变得正确。那么有人可以解释这种行为并提出解决这个问题的正确方法吗?