等待 Kotlin 协程导致 Java

Question

I would like rewrite all AsyncTask to Kotlin Coroutines . Call and wait for result from Coroutines in Java code. For example: I have some long time consumable method in Kotlin .

Kotlin:

class Coroutines {
     suspend fun readFile(): String {
         return GlobalScope.async {
            read long file...
          }.await()
     }
}

Now, i would like to wait (but no block UI thread) for complete method, ideally without a callbacks.

Java:

public class MainActivity extends AppCompatActivity {
    ...

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        ...
        Coroutines c = new Coroutines();
        c.readFile(); //Wait for result but no block UI thread
    }
}

Answer 1

Basically a coroutine suspend function can only be called from another suspend function or from coroutines builder like async or launch. Since java doesn't have the support for coroutine,you can't launch it from java code.

But mix of both can be possible, for example you can create a viewmodel with live data which gets updated from coroutine launched form viewModelScope. The result or progress can be observed in activity/fragment.

Hope this helps you.