What is the best way to store Date in savedInstanceState?

Question

I am using the onSaveInstanceState method to store and retrieve local variables inside a fragment. I have the following code (simplified) in one of my fragments :

private final SimpleDateFormat dateFormat = new SimpleDateFormat("dd/MM/yyyy - HH:mm");
private Date myDate;

public Date getDate() { return myDate; }

public void setDate(Date date) { this.myDate = date; }

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.main, container, false);

    TextView tvDate = (TextView) rootView.findViewById(R.id.textview_date);

    if (savedInstanceState != null) {
        try {
            myDate = dateFormat.parse(savedInstance.State.getString("DATE"));
        catch (ParseException e) {
        }
    }

    //myDate is being set by a different fragment using the setDate method

    if (tvDate != null)
        tvDate.setText(dateFormat.format(myDate));

    return rootView;
}

@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
    super.onSaveInstanceState(savedInstanceState);
    savedInstanceState.putString("DATE", dateFormat.format(myDate));
}

This way I can store and retrieve the date value when my view gets destroyed and recreated, by rotating the screen for example, which is was the main problem. This works, but I can tell this isn't efficient. If I store more variables like this, the view creation is taking much longer (a few seconds to load for 10 variables containing strings and booleans).

I was wondering if there is a better way to do this. Any suggestion is welcome.

Answer 1

Your code does not seem to cause performance issues and is the normal and efficient way to store your state on Android. I've added some comments/adjustments to your code below however which might tackle other errors or could speed things up.

    private static final String STATE_DATE = "state:date";

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, e Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.main, container, false);

        TextView tvDate = (TextView) rootView.findViewById(R.id.textview_date);

        // Check if the savedInstanceSTate contains the date String key.
        if (savedInstanceState != null
                && savedInstanceState.containsKey(STATE_DATE)) {

            try {
                // Consider doing complex tasks like parsing etc. in the background.
                // Parsing a date shouldn't be the issue here but doing many things like this may 
                // be the cause of the performance issue. 
                myDate = dateFormat.parse(savedInstanceState.getString(STATE_DATE));
                catch(ParseException e){
                }
            }

            //myDate is being set by a different fragment using the setDate method

            if (tvDate != null)
                tvDate.setText(dateFormat.format(myDate));

            return rootView;

        }
    }

    @Override
    public void onSaveInstanceState(Bundle savedInstanceState) {
        super.onSaveInstanceState(savedInstanceState);
        // Remove the date formatter here. Try to format your date immediately when storing it in the variable.
        // When restoring your date from your savedInstanceState you're already formatting it.
        savedInstanceState.putString(STATE_DATE, myDate);
    }