AsyncTask和上下文

Question

所以我正在使用Android和AsyncTask类开发我的第一个多线程应用程序.我正在尝试使用它在第二个线程中触发Geocoder,然后使用onPostExecute更新UI,但我仍然遇到了正确的Context问题.

我在主线程上使用Contexts有点蠢蠢欲动,但我不确定Context是什么或如何在后台线程上使用它,我还没有找到任何好的例子.有帮助吗？以下是我要做的事情的摘录:

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);
  }
}

由于上下文不正确,它在第六行仍然失败.

Answer 1

@Eugene van der Merwe

以下代码对我有用:) - >

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

Answer 2

我做了更多研究，有人建议将其传递给线程（不知道为什么我没有想到这一点）。我通过参数将其传递给地理编码器线程，就像这样，它起作用了。