观察阵列中的单个元素

Question

我在这里遇到了两个代码问题，

1. 如何创建一个可以观察单个数组项而不是整个数组的观察者。

2. AndroidSchedulers.mainThread((正在引发错误

   override fun onCreate(savedInstanceState: Bundle?) {
   super.onCreate(savedInstanceState)
   setContentView(R.layout.activity_main)
   val greetings = arrayOf("Hello A", "Hello B", "Hello C")
   val observable = Observable.fromArray(greetings)
   val observer = object: DisposableObserver<Array<String>>() {
   override fun onNext(t: Array<String>?) {
   println(t)
   }
   override fun onError(e: Throwable?) {
   }
   override fun onComplete() {
   }
   }
   observable.subscribeOn(Schedulers.io())
   .observeOn(AndroidSchedulers.mainThread())
   .subscribeWith(observer)
   

   }

来自#2 的错误

E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.fromarraydemo, PID: 11002
java.lang.NoSuchMethodError: No static method metafactory(Ljava/lang/invoke/MethodHandles$Lookup;Ljava/lang/String;Ljava/lang/invoke/MethodType;Ljava/lang/invoke/MethodType;Ljava/lang/invoke/MethodHandle;Ljava/lang/invoke/MethodType;)Ljava/lang/invoke/CallSite; in class Ljava/lang/invoke/LambdaMetafactory; or its super classes (declaration of 'java.lang.invoke.LambdaMetafactory' appears in /apex/com.android.art/javalib/core-oj.jar)
at io.reactivex.rxjava3.android.schedulers.AndroidSchedulers.<clinit>(AndroidSchedulers.java:33)
at io.reactivex.rxjava3.android.schedulers.AndroidSchedulers.mainThread(AndroidSchedulers.java:44)
at com.example.fromarraydemo.MainActivity.onCreate(MainActivity.kt:36)

---

尝试#1

val observer = object: DisposableObserver<String>() {
override fun onNext(t: String?) {
TODO("Not yet implemented")
}
override fun onError(e: Throwable?) {
TODO("Not yet implemented")
}
override fun onComplete() {
TODO("Not yet implemented")
}
}

但是CCD_ 1有问题

Type mismatch: inferred type is <no name provided>! but Observer<in Array<String>!>! was expected

Answer 1

关于错误#1，我认为有一个函数

val observable = greetings.toObservable()

它似乎做了你想要的(与你的尝试DisposableObserver<String>一起使用(

关于错误#2，我复制粘贴了你的代码，在AndroidSchedulers.mainThread((上没有收到任何错误，但我使用的是rxjava2，所以这不是完全相同的情况。(我在这里做的唯一更改是从String和Throwable中删除可选项(

如果您找不到更好的解决方案，那么返回rxjava2可能是一种选择？

Answer 2

Based on @AppDeveloper's comment,
"i mean i want to iterate through all values for the array and want on observe each one on the 'onNext'"

您可以使用
fromIterable()弹出此数组中的每个值，并在onNext((上观察每个值
fromArray()是弹出整个阵列。

Observable.fromIterable(arrays)
.subscribeOn(SchedulerProvider.io())
.observeOn(SchedulerProvider.mainThread())
.subscribe(
{TODO("do on Next")},
{TODO("do on Error")}
)