I have a problem with adding the fragment transactions to the back stack. I have a Main activity in which I populate my layout with a Menu Fragment:
public class MainActivity extends ActionBarActivity{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
getFragmentManager().beginTransaction().add(R.id.frag_container, new MainMenuFragment()).commit();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
Then, inside the MainMenuFragment, the user chooses some option which results in replacing the menu fragment with some other fragment:
public class MainMenuFragment extends Fragment implements OnItemClickListener{
GridView grid;
FragmentManager manager;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View root = inflater.inflate(R.layout.main_menu_fragment, container, false);
manager = getActivity().getFragmentManager();
grid = (GridView) root.findViewById(R.id.gridView1);
grid.setAdapter(new MenuTileAdapter(getActivity()));
grid.setOnItemClickListener(this);
return root;
}
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
FragmentTransaction trans = manager.beginTransaction();
if (position == 0){
trans.replace(R.id.frag_container, new BasicSettingsFragment());
trans.addToBackStack(null);
trans.commit();
}
}
}
For what i understand, this should make it so that when the user presses back button on their device, they will be brought back to the menu fragment, but instead this quits the app. What am i doing wrong?
You can get a reference to the FragmentActivity by calling getActivity() on your current Fragment and then call from the Activity retrieved onBackPressed() method.
Calling addToBackStack() commits the transaction to the back stack. The user can later reverse the transaction and bring back the previous fragment by pressing the Back button. If you added or removed multiple fragments within a single transaction, all of those operations are undone when the back stack is popped.
Calling setRetainInstance(true) will prevent the Fragment from being re-created. But, right now the Activity is always re-creating the DrawerFragment and forcefully re-creating the HomeFragment , resulting in the behavior you are seeing. In your Activity. onCreate() check the savedInstanceState is null .
The title of the toolbar should change between the two fragments (from "First Fragment" to "Second Fragment"). The second fragment should have a "back button" (arrow left icon) in the toolbar that, on click, lets the user go back to the first fragment.
In your Activity overwrite:
@Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() > 0) {
getFragmentManager().popBackStack();
} else {
super.onBackPressed();
}
}
And probably you need to use in every commited fragment transaction:
FragmentTransaction.addToBackStack(null);
Your code is a mixup, you use ActionBarActivity from appcompat and not using getSupportFragmentManager() and the fragments import should be the appcompat one if you decide to use it. If not, use Activity instead of ActionBarActivity and the simple Fragment import with FragmentManager
Add this to your activity android:configChanges="keyboardHidden|orientation|screenSize"
This will stop your activity from restarting when you rotate.
use setRetainInstance(true)
on fragments.
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