AsyncTask线程的问题

Question

我正在 AsyncTask 线程中从数据库读取一些数据...... 这样：

    protected Void doInBackground(DBAdapter... db) {

        try {

            db[0].openDataBase();

            Cursor c = db[0].getCursor3(db[0].TABLE_3, user_id);

            float[] viteza = new float[c.getCount()];

            String[] time = new String[c.getCount()];

            if (c.moveToFirst()) {

                do {

                    viteza[i] = Float.parseFloat(c.getString(3));
                    time[i] = c.getString(4);


                    publishProgress(????);

                    Thread.sleep(2500);

                    i++;
                } while (c.moveToNext());

            }
            c.close();
            db[0].close();

        } catch (Exception e) {
            Log.d("Eroare", "doInBackground", e);
        }

        return null;
    }

我的问题是，每次我获得 viteza[i] 和 time[i] 的新值时，我必须

protected void onProgressUpdate(....?) {

}

同时将它们发送给两者......但我不知道该怎么做因为publishProgress()只能接受一个参数！！！！

有人可以帮我吗？谢谢

Answer 1

假设您已按正确顺序获取数据值（getString(3) 应该是数字，getString(4) 应该是时间值），以下内容应该可以工作。

protected Void doInBackground(DBAdapter... db) {
    // ... some db work
    if (c.moveToFirst()) {
        publishProgress(c.getString(3), c.getString(4));
        // ...
    }
}

protected void onProgressUpdate(String... values) {
    float viteza = Float.parseFloat(values[0]);
    String time = values[1];
    // do something with the data that shows in UI
}

用于测试传递值的完整 AsyncTask 位于：

private class SimpleTask extends AsyncTask<Void, String, Void> {

    @Override
    protected Void doInBackground(Void... params) {
        String floatAsString = "3.14159265358979";
        String timeAsString = "06-01 07:32:02.579";
        publishProgress(floatAsString, timeAsString);
        return null;
    }

    @Override
    protected void onProgressUpdate(String... values) {
        float pi = Float.parseFloat(values[0]);
        Log.i("SimpleTask", String.format("Got values '%s' and '%s'. pi = %f", values[0], values[1], pi));
    }

}

打印输出：

Got values '3.14159265358979' and '06-01 07:32:02.579'. pi = 3.141593

Answer 2

您可以将它们保留为 String 并将 String[] 数组传递给publishProgress()，保持相同的顺序，然后在publishProgress() 中将 viteza[i] 的值转换为浮点数。如果您不想担心数组顺序，您也可以将它们放入一个超级简单的类中并传递对象，但对于这么小的东西，我会使用数组。

public class HelloAndroid extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    MyAsyncTask myTask = new MyAsyncTask();
    myTask.execute();
}

private class MyAsyncTask extends AsyncTask<Void, String, Void> {

    @Override
    protected Void doInBackground(Void... arg0) {
        // TODO Auto-generated method stub
        String[] first = {"1", "2", "3", "4", "5"};
        String[] second = {"5", "4", "3", "2", "1"};

        for(int i = 0; i < first.length; i++) {
                            //put together a string array with our values in the desired order
            String[] vals = {first[i], second[i]};
                            //publishProgress is what is used to call onProgressUpdate()
            publishProgress(vals);
        }
        return null;
    }

    @Override
    protected void onProgressUpdate(String...strings ) {

                    //Strings are now in strings[0] and strings[1] in the order
                    //that they were put into vals array in doInBackground()
        String passedValues = strings[0] + "," + strings[1];

                    //Do whatever UI updates.
        TextView mytext = (TextView)findViewById(R.id.mytext);
        mytext.setText(passedValues);
    }

}

}

Answer 3

考虑一个包装这两个值的自定义对象，并将该对象作为 Progress 传递，如下所示：

private class MyAsynch extends AsyncTask<Void,MyObject,Void>{

JAL