Intent gets lost when using "up" button in master/detail template

Question

I'm using the master/detail template in my Android app which works well on the tablet. However, in the handset version I keep getting a nullpointer exception when clicking the "up" button in the ListActivity.

When debugging I see that when clicking the "up" button in the detail fragment I return to the parent activity (the listactivity) and get back into the onCreate() method. In there I'm doing:

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_gamelist);
    String systemStr = getIntent().getStringExtra("systemObj");
    ...
}

But when returning to this from the detail fragment the intent is null and therefore I'm getting a nullpointer exception when accessing systemStr.

What do I need to do in order to avoid this nullpointer exception when I click "up" in the detail fragment to get back to the list activity? As mentioned above, the tablet (two pane) version works, the problem is just in the handset version.

Answer 1

I couldn't find any solution for the problem so I ended up using this code in the detail activity to avoid the nullpointer exception:

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
    // When pressing the UP button in the action bar simulate the "back" button.
    case android.R.id.home:
        onBackPressed();
        return true;
    }
    return super.onOptionsItemSelected(item);
}

At least that solution won't crash my app.