CODEWITHSUNDEEP
androidandroid-fragmentsandroid-fragmentactivityback-button
hahahakebab
hahahakebab

Reputation: 326

Back navigation in title bar - fragment

There are many questions like this asked but everything I have tried seems to not work. Essentially I have a main activity that calls different fragments depending on what the user clicks with the home fragment being default. I would like to have a back button on the title bar, to go back to the previous fragment.

My fragment is called from the main activity like so:

    Fragment fragment = null;
    fragment = new nextFragment();

    if (fragment != null) {
        FragmentManager fragmentManager = getFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

        fragmentTransaction.replace(R.id.frame_container, fragment).addToBackStack(null);
        fragmentTransaction.commit();
        fragmentTransaction.addToBackStack(null);

    } else {
        // error in creating fragment
        Log.e("MainActivity", "Error in creating fragment");
    }

But since ActionBarActivity activity is deprecated I need to extend AppCompatActivity instead of FragmentActivity so I can use actionbar (I'm assuming this is what I need). However then I am unable to switch to my fragment. So does anyone know how I could implement a back button in my fragment or how to use AppCompatActivity in this situation. Thanks for any help.

Upvotes: 1

Views: 9358

Answers (3)

XepterX
XepterX

Reputation: 1011

You've saved the last fragment used by calling

addToBacktack(null).commit()

So the next step forward to call it is by overriding onBackPressed() in the activity hosting the fragment.

@Override
public void onBackPressed() {
    if (getFragmentManager().getBackStackEntryCount() > 0 ){
        getFragmentManager().popBackStack();
    }
    else {
        super.onBackPressed();
    }
}

So whenever you call the activity's onBackPressed() from the fragment, the fragment would go back to the last saved fragment.

Upvotes: 1

Siu
Siu

Reputation: 1432

Please try this if you extend AppCompatActivity:

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //Include these 2 lines ONLY if need to use Toolbar from layout xml as Action Bar
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        //Add back navigation in the title bar
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);

        //
        //Other works to be done in onCreate.....
        //
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if (item.getItemId() == android.R.id.home) {
            //Title bar back press triggers onBackPressed()
            onBackPressed();
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    //Both navigation bar back press and title bar back press will trigger this method
    @Override
    public void onBackPressed() {
        if (getFragmentManager().getBackStackEntryCount() > 0 ) { 
            getFragmentManager().popBackStack(); 
        } 
        else { 
            super.onBackPressed(); 
        }
    }
}

Upvotes: 8

Abhi
Abhi

Reputation: 3511

To add Back Button in title bar, you must add the following code to your Fragment.

 Toolbar toolbar = (Toolbar)view.findViewById(R.id.app_bar);
 AppCompatActivity AppCompatActivity = (AppCompatActivity)getActivity();
 AppCompatActivity.setSupportActionBar(toolbar);
 AppCompatActivity.getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    return view;
}

Don't forget to extend your MainActivity to AppCompatActivity.

You must then use this Java code in my Fragment class to react to the user tapping the back/up icon in the action bar. 

@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
    case android.R.id.home:            
        getActivity().onBackPressed();
        return true;
    default:
        return super.onOptionsItemSelected(item);
}
}

Upvotes: 3

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