AsyncTask的和上下文 [英] AsyncTask and Contexts

问题描述

所以我使用的是Android与AsyncTask的类的工作我的第一个多线程应用程序。我试图用它来火了一个地理codeR在第二个线程，然后更新与onPostExecute用户界面，但我依然会碰到一个问题，正确的上下文。

So I'm working out my first multi-threaded application using Android with the AsyncTask class. I'm trying to use it to fire off a Geocoder in a second thread, then update the UI with onPostExecute, but I keep running into an issue with the proper Context.

我通过使用上下文在主线程中步履蹒跚我的路，但我不完全确定的上下文是什么或如何使用它在后台线程，而我还没有找到任何很好的例子。任何帮助吗？这里是我想要做的摘录：

I kind of hobbled my way through using Contexts on the main thread, but I'm not exactly sure what the Context is or how to use it on background threads, and I haven't found any good examples on it. Any help? Here is an excerpt of what I'm trying to do:

public class GeoCode extends AsyncTask<GeoThread, Void, GeoThread> {
  @Override
  protected GeoThread doInBackground(GeoThread... i) {
    List<Address> addresses = null;
    Geocoder geoCode = null; 
    geoCode = new Geocoder(null); //Expects at minimum Geocoder(Context context);
    addresses = geoCode.getFromLocation(GoldenHour.lat, GoldenHour.lng, 1);
  }
}

它不断失败，因为不正确的语境中，在第六行那里。

It keeps failing at the sixth line there, because of the improper Context.

推荐答案

@Eugene的van der Merwe的

@Eugene van der Merwe

下面这段code对我的作品：） - >

The following piece of code works for me : ) -->

public class ApplicationLauncher extends Activity {

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

    LoadApplication loadApplication = new LoadApplication(this);
    loadApplication.execute(null);
}

private class LoadApplication extends AsyncTask {

    Context context;
    ProgressDialog waitSpinner;
    ConfigurationContainer configuration = ConfigurationContainer.getInstance();

    public LoadApplication(Context context) {
        this.context = context;
        waitSpinner = new ProgressDialog(this.context);
    }

    @Override
    protected Object doInBackground(Object... args) {
        publishProgress(null);
        //Parsing some stuff - not relevant
        configuration.initialize(context);
        return null;
    }

    @Override
    protected void onProgressUpdate(Object... values) {
        super.onProgressUpdate(values);
        // Only purpose of this method is to show our wait spinner, we dont
        // (and can't) show detailed progress updates
        waitSpinner = ProgressDialog.show(context, "Please Wait ...", "Initializing the application ...", true);
    }

    @Override
    protected void onPostExecute(Object result) {
        super.onPostExecute(result);
        waitSpinner.cancel();
    }
}
}

干杯，

Ready4Android

Ready4Android

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