android - 从 AsyncTask 调用 UI 线程方法

Question

我在从 AsyncTaskActivity onPostExecute() 方法内部调用 setadapter() 方法时遇到问题。我读过有关 AsyncTask 的文档:http://developer.android.com/reference/android/os/AsyncTask.html#onPostExecute(Result ) 但没有找到如何实现的答案。我应该使用 Intent 这样做吗？我是 Android 开发的新手，所以如果这是一个愚蠢的问题，请原谅我。

主要 Activity

public class MainActivity extends ListActivity {

private String[] columns = new String[] {"foreign_word", "native_word"};
private int[] target = new int[] { R.id.foreign_word, R.id.native_word };
private Cursor cur = null;

 @Override
 protected void onCreate(Bundle savedInstanceState){
     super.onCreate(savedInstanceState);

     new AsyncTaskActivity(this).execute();
 }

    public void setadapter(Cursor cur)  {
        SimpleCursorAdapter aaa = new SimpleCursorAdapter(this.getApplicationContext(), R.layout.list_entry, cur, columns, target, 0);
        this.setListAdapter(aaa);
    }
}

异步任务 Activity

public class AsyncTaskActivity extends AsyncTask<Void, Void, Cursor> {

Activity activity = null;
private SQLiteDatabase db = null;
private String[] selection = {"_id", "native_word", "foreign_word"};
Cursor cur = null;


public AsyncTaskActivity(Activity activity) {
    this.activity = activity;
}

@Override
protected Cursor doInBackground(Void... params) {
    DbAdapter mSQLadapter = new DbAdapter(activity);
    db = mSQLadapter.getWritableDatabase();
    Cursor cur = db.query("words", selection, "foreign_word='car'", null, null, null, null);
    return cur;
}

protected void onPostExecute(Cursor cur) {

// I'd like to call setadapter() ,passing it Cursor as a parameter

   }

}

Answer 1

假设您的 AsyncTask 总是被 MainActivity 调用，执行此操作

protected void onPostExecute(Cursor cur) {
   MainActivity mActivity = (MainActivity) activity;
   mActivity.setadapter();
   }

您可以为您的setAdapter 方法指定更多参数，这样您就可以传递Cursor、String 数组等。

然而，如果 AsyncTask 仅从 MainActivity 调用，则更好的方法是使此 AsyncTask 成为 中的私有(private)内部类主 Activity 。这将允许它访问 MainActivity

的所有全局变量和方法