CODEWITHSUNDEEP
javaandroidandroid-fragments
Tony Starkus
Tony Starkus

Reputation: 576

BottomNavigation Item Selected Animation onBackPressed

I have a app with BottomNavigation (3 Items). The Item 1 load Fragment 1, Item 2 load fragment 2 and Item 3 load fragment 3. When one item is selected in the BottomNavigation, the view of this item keep blue and the text is more big. I have implemented onBackPressed, for it back the fragment history (BackStack). But, when i'm backing, the views in BottomNavigation are stoppe. So, if i'm in fragment 3, and i press back button and it back to fragment 2, the BottomNavigationView show that i'm in fragment 3, and if i press back button again, i go to fragment1, but the BottomNavigationView don't update, it keep in Fragment 3. The screenshorts will show what i'm talking about. Sorry my bad english and my bad explanation.

enter image description here

enter image description here

MainActivity.java

public class MainActivity extends AppCompatActivity {

private TextView mTextMessage;

private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
        = new BottomNavigationView.OnNavigationItemSelectedListener() {

    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem item) {
        Fragment selectedFragment = null;
        switch (item.getItemId()) {
            case R.id.navigation_home:
                selectedFragment = Fragment1.newInstance();
                getSupportFragmentManager().beginTransaction().replace(R.id.content, selectedFragment).addToBackStack(null).commit();
                return true;
            case R.id.navigation_dashboard:
                selectedFragment = Frament2.newInstance();
                getSupportFragmentManager().beginTransaction().replace(R.id.content, selectedFragment).addToBackStack(null).commit();
                return true;
            case R.id.navigation_notifications:
                selectedFragment = Fragment3.newInstance();
                getSupportFragmentManager().beginTransaction().replace(R.id.content, selectedFragment).addToBackStack(null).commit();
                return true;
        }
        return false;
    }

};

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

    BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
    navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
}

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

Upvotes: 0

Views: 742

Answers (1)

Ben P.
Ben P.

Reputation: 54204

From the Material Design guidelines for bottom navigation:

On Android, the Back button does not navigate between bottom navigation bar views.

And from the Developer Training for Back Navigation:

Note: You should not add transactions to the back stack when the transaction is for horizontal navigation (such as when switching tabs)

So you should not use the back stack when replacing fragments based on user interaction with your BottomNavigationView.

If you choose to ignore these guidelines, probably the answer is to look into FragmentManager.OnBackStackChangedListener and activate the appropriate navigation item when you pop the back stack.

Upvotes: 1

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