如何在两个不同的类中使用相同的计数器

Question

I am creating a login fragment where the user can maximum try 3 times to login.

TO do so I wanted to use a counter in the fragment , but given that this fragment also contains an asynctask class for connecting to internet, it also needs to use the counter variable.

I know I could work with SharedPreferences but i was wondering if there was any better approach on it.

The code would be as follows:

public class loginfragment extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {

        button.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View v)
            {
                //CONNECT TO INTERNET!!
                task=new PasswordCheckTask();
                task.execute();
                //END CONNECT TO INTERNET!!
            }
        });
   }

   class PasswordCheckTask extends AsyncTask<Void, Void, Void> {

        @Override
        protected void onPostExecute(Void result) {

            if (success == "1"){
                 Intent xx = new Intent(getContext().getApplicationContext(), ArduinoFirst.class);
                 xx.putExtra("position", position);
                 startActivity(xx);
                 counter=3; //Counter goes back to 3
            } else if (counter!=0) {
                 counter=counter-1 //One less try
            }
       }
 }

How would you do it?

Answer 1

您可以使用静态变量在任何地方都可以正常工作

Answer 2

In your example, the PasswordCheckTask class is a subclass of loginfragment (btw, the convention is to name it LoginFragment ). So you could technically define a variable counter of LoginFragment and it can be accessed by both.

However, note that you're dealing with threads here, so you should use something like AtomicInteger or wrap calls to it using the synchronized keyword.

Example:

public class LoginFragment extends Fragment {

    private AtomicInteger counter = new AtomicInteger();

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {

        button.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View v)
            {
                //CONNECT TO INTERNET!!
                task=new PasswordCheckTask();
                task.execute();
                //END CONNECT TO INTERNET!!
            }
        });
   }

   class PasswordCheckTask extends AsyncTask<Void, Void, Void> {

        @Override
        protected void onPostExecute(Void result) {

            if (success == "1"){
                 Intent xx = new Intent(getContext().getApplicationContext(), ArduinoFirst.class);
                 xx.putExtra("position", position);
                 startActivity(xx);
                 counter.set(3);
            } else if (counter.get() != 0) {
                 counter.getAndDecrement();
            }
       }
 }

However, I've only seen you use the counter in the subclass PasswordCheckTask so you could have just defined it inside it, unless I've missed something.

Answer 3

您可以创建一个Utils类，并在其中定义一个public static int变量，您可以从代码的任何地方访问该变量。