Question

我在创建一个在后台运行的方法时遇到了一些问题。我正在使用Android studio java，并希望创建一个在array-list中加载文本文件的方法。我试图在与活动类不同的类中的公共方法中执行此操作。当我运行应用程序时，我遇到问题表明主线程有问题，所以我想制作一个asynctask。我看过整个互联网，但我找不到任何相关的东西。因为我是初学者，请问一下有什么不清楚的地方。任何帮助表示赞赏！

这是一个将变量发送到public void CreateQuestion()的类，它位于第一个代码之下：

protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_game_action);

    Intent callingIntent = getIntent();
    int index = callingIntent.getIntExtra("INDEX",0);      


    if(index==0){
        mQuestionBox = new QuestionBox();
        try {
            mQuestionBox.createQuestions("hogskoleprovet.txt");
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
    else if(index==1){
        mQuestionBox = new QuestionBox();
        try {
            mQuestionBox.createQuestions("hogskoleprovet.txt");
        } catch (IOException e) {
            e.printStackTrace();
        }


    }
    else if(index==2){
        mQuestionBox = new QuestionBox();
        try {
            mQuestionBox.createQuestions("hogskoleprovet.txt");
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

我想把这段代码作为asynctask，但我不知道怎么做。

public void createQuestions(String hogskoleprovet)  throws IOException {


    InputStream iS = sContext.getAssets().open(hogskoleprovet);
    BufferedReader reader = new BufferedReader(new InputStreamReader(iS));

    mQuestions = new ArrayList<Question>();


    String question, answer, answerOne, answerTwo, answerThree, answerFour;



    while (reader.readLine() != null) {

        //reading some lines from resource file
        question = reader.readLine();
        answer = reader.readLine();
        answerOne = reader.readLine();
        answerTwo = reader.readLine();
        answerThree = reader.readLine();
        answerFour = reader.readLine();
        Question q = new Question(question, answer, answerOne, answerTwo, answerThree, answerFour);
        mQuestions.add(q);
        break;
    }

    reader.close();


}

Answer 1

尝试修改您的createQuestions方法，如下所示：

public void createQuestions(final String hogskoleprovet) throws IOException {

new AsyncTask<Integer, Integer, Boolean>()
    {

        @Override
        protected void onPreExecute()

        {

        }

        @Override
        protected Boolean doInBackground(Integer… params)
        {

          InputStream iS = sContext.getAssets().open(hogskoleprovet);
          BufferedReader reader = new BufferedReader(new InputStreamReader(iS)); 

        mQuestions = new ArrayList<Question>();


        String question, answer, answerOne, answerTwo, answerThree, answerFour;



  while (reader.readLine() != null) {

       //reading some lines from resource file
       question = reader.readLine();
       answer = reader.readLine();
       answerOne = reader.readLine();
       answerTwo = reader.readLine();
       answerThree = reader.readLine();
       answerFour = reader.readLine();
       Question q = new Question(question, answer, answerOne, answerTwo, answerThree, answerFour);
      mQuestions.add(q);
      break;
  }

  reader.close();


            return true;
        }

        @Override
        protected void onPostExecute(Boolean result)
        {




        }
    }.execute();
 }

Answer 2

Asynctask类从文件中读取数据

public class FileReader_async extends AsyncTask{
private Context context;
private Callback callback;
private List<Question> mQuestions;
    public FileReader_async(Context context,Callback callback)
    {
        this.callback=callback;
    }
    @Override
    protected Object doInBackground(Object... params) {
        InputStream iS = null;
        try {
            iS = context.getAssets().open("filename");
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        BufferedReader reader = new BufferedReader(new InputStreamReader(iS));

        mQuestions = new ArrayList<Question>();


        String question, answer, answerOne, answerTwo, answerThree, answerFour;



        try {
            while (reader.readLine() != null) {

                //reading some lines from resource file
                question = reader.readLine();
                answer = reader.readLine();
                answerOne = reader.readLine();
                answerTwo = reader.readLine();
                answerThree = reader.readLine();
                answerFour = reader.readLine();
                Question q = new Question(question, answer, answerOne, answerTwo, answerThree, answerFour);
                mQuestions.add(q);
                break;
            }
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        try {
            reader.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return 0;
    }
    @Override
    protected void onPostExecute(Object result) {
        // TODO Auto-generated method stub
        super.onPostExecute(result);
        callback.notify_result(mQuestions);
    }



}

回调接口，在asnyctask完成时通知

public interface Callback {

    public void notify_result(List<Question> question_list);


}

调用asynctask从文件中读取数据的活动..

public class MainActivity extends ActionBarActivity implements Callback{
private  FileReader_async fileReader_async;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        //invoke the asynctask when you want to read the question.. to invoke asynctask code 

        fileReader_async=new FileReader_async(getApplicationContext(), this);
        fileReader_async.execute();
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }


    @Override
    public void notify_result(List<Question> question_list) {
        //you can use the question_list from here

    }
}

创建AsyncTask的问题。 arraylist中的文本文件

2 个答案: