Returning (onClickBack) to activity that grabs serialiazable extra

Question

I've tried a vast variety of solutions and can't seem to figure out the best way to implement this specific problem without using cheap hacks (such as saving data to sharedpreferences, etc.)

I have an activity that requires data from the intent extras:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_view_problem_set);
    ButterKnife.bind(this);

    this.problemSet = (ProblemSet) getIntent().getSerializableExtra("problemSet");
    ...
}

When a user clicks on a specific problem within the problem set, I have a new activity that is spawned that simply just views data associated to a particular problem within the problem set. Note, this is just simply a view of the data (there is no need to start the activity for result as nothing is returned).

_problemsList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            Problem problem = ViewProblemSetActivity.this.problemSet.getProblems().get(position);
            Log.d(TAG, "clicked on problem + " + problem.toString());
            Intent problemFeedbackActivity =
                    new Intent(ViewProblemSetActivity.this, ProblemFeedbackActivity.class);
            problemFeedbackActivity.putExtra("problem", problem);
            startActivity(problemFeedbackActivity);
        }
    });

However, when I click back and return to the existing onCreate activity, the intent extras are null. What is the best way to handle this kind of situation in android?

I have tried solution attempts such as saving the extra to the savedInstanceState but when onCreate is called my savedInstanceState is still null:

Losing Intent extras when returning to Activity

Would persisting this data on the onPause method make more sense?

Saving Android Activity state using Save Instance State

EDIT:

I implemented the savedInstanceState functionality yet still seem the same behavior (empty Intent extras and null savedInstanceState) when returning to the previous activity. I added the following to the first activity:

@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
    Log.d(TAG, "ViewProblemSetActivity.onSaveInstanceState savedInstanceState=" + savedInstanceState);
    super.onSaveInstanceState(savedInstanceState);
    savedInstanceState.putSerializable("problemSet", problemSet);
}

@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
    Log.d(TAG, "ViewProblemSetActivity.onRestoreInstanceState savedInstanceState=" + savedInstanceState);
    super.onRestoreInstanceState(savedInstanceState);
    this.problemSet = (ProblemSet)savedInstanceState.getSerializable("problemSet");
}

@Override
protected void onResume() {
    Log.d(TAG, "ViewProblemSetActivity.onResume");
    super.onResume();
}

@Override
protected void onPause() {
    Log.d(TAG, "ViewProblemSetActivity.onPause");
    super.onPause();
}

Here is the log of beginning with the first activity create, going to the second activity, then returning to the second activity.

03-30 13:23:50.021 2540-2540/io.gradem.gradem D/view_ps_activity: ViewProblemSetActivity.onCreate savedInstanceState=null
03-30 13:23:50.026 2540-2540/io.gradem.gradem D/view_ps_activity: ViewProblemSetActivity.onResume
03-30 13:23:54.324 2540-2540/io.gradem.gradem D/view_ps_activity: clicked on problem 
03-30 13:23:54.337 2540-2540/io.gradem.gradem D/view_ps_activity: ViewProblemSetActivity.onPause
03-30 13:23:54.354 2540-2540/io.gradem.gradem D/activity_feedback: ProblemFeedbackActivity.onCreate savedInstanceState=null
..... some over behavior before returning to previous activity ....
03-30 13:30:12.377 7266-7266/io.gradem.gradem D/view_ps_activity: ViewProblemSetActivity.onSaveInstanceState savedInstanceState=Bundle[{}]
03-30 13:23:58.861 2540-2540/io.gradem.gradem D/view_ps_activity: ViewProblemSetActivity.onCreate savedInstanceState=null

score 1 · Accepted Answer · answered Mar 30 '16 at 17:07

1

savedInstanceState should actually solve the problem, but using a singleton class seems easier.

answered Mar 30 '16 at 17:07

ozo

763
7
13

I went ahead and implemented it and still see strange behavior. See my edit. – leerobert Mar 30 '16 at 17:28
Use a singleton class, it's easier. – ozo Mar 30 '16 at 17:33
Just looked that up... https://gist.github.com/Akayh/5566992... its brilliant. Thanks for the comment. The fact the extras aren't being persisted clearly is some kind of design flaw though. Thanks for the help. – leerobert Mar 30 '16 at 17:35

Returning (onClickBack) to activity that grabs serialiazable extra

EDIT:

1 Answers1