Question

我正在尝试使用RxAndroid执行与AsyncTask完全相同的工作。我编写了一个简单的例子，我在edittext中输入一个n整数，当我按下时一个按钮，我使用“SystemClock.sleep”让hread进入睡眠状态3秒，当线程处于休眠状态时，我显示一个进度条，当三秒钟已经过了进度条，并且在edittext中输入的值将乘以10并显示在文本视图中。

通常，当我使用AsyncTask时，我会在onPreExecute中显示进度条并使其在onPostExecute中消失。但是当我运行以下代码时，我收到了以下错误：

Only the original thread that created a view hierarchy can touch its views.

如何在RxAndroid中正确处理它？</ p>

码：

public class MainActivity extends AppCompatActivity {

private static final String TAG = MainActivity.class.getSimpleName();
private EditText mEditTextValueToProcess = null;
private Button mButtonGoAsynchronous = null;
private TextView mTextViewProcessedValue = null;
private ProgressBar mProgressBar = null;
private rx.Observable<String> mAsyncObservable = null;

Subscriber mAsyncSubscriber = new Subscriber<String>() {
    @Override
    public void onCompleted() {
        Log.w(TAG, "onCompleted");
        mProgressBar.setVisibility(View.GONE);
    }

    @Override
    public void onError(Throwable e) {
        Log.w(TAG, "onError: " + e.getMessage().toString());
        mProgressBar.setVisibility(View.GONE);
    }

    @Override
    public void onNext(String o) {
        Log.w(TAG, "onNext:->after processing " + o);
        mTextViewProcessedValue.setText(o);
    }
};

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    intiViews();

    mAsyncObservable = rx.Observable.create(new rx.Observable.OnSubscribe<String>() {
        @Override
        public void call(Subscriber<? super String> subscriber) {
            mProgressBar = (ProgressBar) findViewById(R.id.progressDialog);
            mProgressBar.setVisibility(View.VISIBLE);

            SystemClock.sleep(3000);

            subscriber.onNext("" + Integer.valueOf(mEditTextValueToProcess.getText().toString()) * 10);
            subscriber.onCompleted();
        }
    });

}

private void intiViews() {
    mEditTextValueToProcess = (EditText) findViewById(R.id.edittext);
    mButtonGoAsynchronous = (Button) findViewById(R.id.button_go_asynchronous);
    mTextViewProcessedValue = (TextView) findViewById(R.id.textview_processed_value);
    //mProgressBar = (ProgressBar) findViewById(R.id.progressDialog);

    mButtonGoAsynchronous.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            mAsyncObservable.subscribeOn(Schedulers.io())
                    .observeOn(AndroidSchedulers.mainThread())
                    .subscribe(mAsyncSubscriber);
        }
    });
}

}

Answer 1

你试过吗

private Observable<String> createObservable(final int number) { 
     return rx.Observable.create(new rx.Observable.OnSubscribe<String>() {
        @Override
        public void call(Subscriber<? super String> subscriber) {
            SystemClock.sleep(3000);

            subscriber.onNext("" + number  * 10);
            subscriber.onCompleted();
        }
    });
}

private void intiViews() {
    mEditTextValueToProcess = (EditText) findViewById(R.id.edittext);
    mButtonGoAsynchronous = (Button) findViewById(R.id.button_go_asynchronous);
    mTextViewProcessedValue = (TextView) findViewById(R.id.textview_processed_value);
    mProgressBar = (ProgressBar) findViewById(R.id.progressDialog);

    mButtonGoAsynchronous.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            mProgressBar.setVisibility(View.VISIBLE);
            createObservable(Integer.valueOf(mEditTextValueToProcess.getText().toString()))
                    .subscribeOn(Schedulers.io())
                    .observeOn(AndroidSchedulers.mainThread())
                    .doOnNext((ignored) -> {
                         mProgressBar.setVisibility(View.GONE);
                    })
                    .subscribe(mAsyncSubscriber);
        }
    });
}

Answer 2

你需要改变一些事情才能实现这一目标。查看mAsyncSubscriber初始化，onStart（）方法＆amp; progressBar初始化。您收到错误的原因是您正在初始化＆amp;使您的进度条在另一个线程中可见，然后是您的UI线程（因为您指定了这个 - ＆gt; subscribeOn(Schedulers.io()）。

public class MainActivity extends AppCompatActivity {

private static final String TAG = MainActivity.class.getSimpleName();
private EditText mEditTextValueToProcess = null;
private Button mButtonGoAsynchronous = null;
private TextView mTextViewProcessedValue = null;
private ProgressBar mProgressBar = null;
private rx.Observable<String> mAsyncObservable = null;
Subscriber mAsyncSubscriber;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    intiViews();

   mAsyncSubscriber = new Subscriber<String>() {

   // Override onStart method
   @Override
   public void onStart() {
        mProgressBar.setVisibility(View.VISIBLE);
   }

    @Override
    public void onCompleted() {
        Log.w(TAG, "onCompleted");
        mProgressBar.setVisibility(View.GONE);
    }

    @Override
    public void onError(Throwable e) {
        Log.w(TAG, "onError: " + e.getMessage().toString());
        mProgressBar.setVisibility(View.GONE);
    }

    @Override
    public void onNext(String o) {
        Log.w(TAG, "onNext:->after processing " + o);
        mTextViewProcessedValue.setText(o);
    }
};


    mAsyncObservable = rx.Observable.create(new rx.Observable.OnSubscribe<String>() {
        @Override
        public void call(Subscriber<? super String> subscriber) {

            SystemClock.sleep(3000);

            subscriber.onNext("" + Integer.valueOf(mEditTextValueToProcess.getText().toString()) * 10);
            subscriber.onCompleted();
        }
    });

}

private void intiViews() {
    // Init your progressbar
    mProgressBar = (ProgressBar) findViewById(R.id.progressDialog);
    mEditTextValueToProcess = (EditText) findViewById(R.id.edittext);
    mButtonGoAsynchronous = (Button) findViewById(R.id.button_go_asynchronous);
    mTextViewProcessedValue = (TextView) findViewById(R.id.textview_processed_value);
    //mProgressBar = (ProgressBar) findViewById(R.id.progressDialog);

    mButtonGoAsynchronous.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            mAsyncObservable.subscribeOn(Schedulers.io())
                    .observeOn(AndroidSchedulers.mainThread())
                    .subscribe(mAsyncSubscriber);
        }
    });
}

如何用RxAndroid替换AsyncTask

2 个答案: