单身人士班，有效利用资源在不同活动中敬酒

Question

I have a singleton class (let's call it: SingleWorker ) that it's used in multiple activities. Depending on the case it shows a toast or a progress dialog if a task is being done. I have 2 ways in my mind on how to do this:

1) creating a separate method in the singleton - SingleWorker, that will get the context of the activity before the toast/progress is shown

2) in the extended Application singleton, I will store, every time I enter a new activity (and on its onResume) its instance, that i will then use that in the SingleWorker singleton.

Which one is the better choice (I guess the first one), can I do it better? I tried to find an efficient answer by myself, but I need a direction or a tip. Any idea, suggestion, advice or link is gratefully received. Thanks for reading !

Answer 1

I was using the second approach for a long time and decided to move to the first one after a few problens. Storing the context in the BaseActivity is better when you need the it outside the context (a background thread for example) To show toast's or dialog's you can just pass it to the method in singleton class ( approach 1), you will be free of memory leaks and will not have to worry about giving the contextStored a new value in onResume() and onDestroy() methods.

Here is an example of a method to show a dialog:

 public static void showAcceptDialog(String message, final Context contex, View.OnClickListener onClickYes, View.OnClickListener onClickNo) {
    dialog = new Dialog(contex);
    dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
    dialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
    dialog.setContentView(R.layout.layout_of_your_dialog);
    TextView tv = (TextView) dialog.findViewById(R.id.generic_accept_message);
    //Seta o titulo do dialogo
    tv.setText(message);
    Button btNo = (Button) dialog.findViewById(R.id.generic_dialog_no);
    if (onClickNo != null) {
        btNo.setOnClickListener(onClickNo);
    } else{
        btNo.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                dialog.dismiss();
            }
        });
    }

    Button btYes = (Button) dialog.findViewById(R.id.generic_dialog_yes);
    if(onClickYes != null){
        // dialog.dismiss();
        btYes.setOnClickListener(onClickYes);
    }
    else {
        btYes.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                dialog.dismiss();
            }
        });
    }
    dialog.show();
}

Answer 2

Toast s are not bound to a specific Activity in terms of their visibility. That's one of the reasons why they where somewhat 'deprecated' (not officially, that's just my interpretation of Google's design guidelines and their own apps) in favor of the Snackbar which is bound to a specific View .

I see no advantage in using an activity context instead of the application context to create a Toast .

Vice versa, when letting your Singleton hold a reference to activity context s, you might very easily create a memory leak by holding on to an already destroyed Activity . You could just pass in the Activity as a method parameter, but that might not be so convenient (eg calling that method from a class other than Activity ).

Long story short: I would suggest to let your SingleWorker have a reference to the application context to create the Toast .