FragmentStateManager

An Android library that holds fragment states for BottomNavigationView. Saves fragment back stack even after activity rotation. Implementation derived from FragmentStatePagerAdapter.

Installation

Add Jitpack to project level gradle file

allprojects {
    repositories {
        maven { url "https://jitpack.io" }
    }
}

Then add library to module level gradle file

dependencies {
  compile 'com.github.okaybroda:FragmentStateManager:1.+'
}

Usage

Create a FragmentStateManager instance in the OnCreate function of your Activity

FragmentStateManager fragmentStateManager;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // ... your code ...
    FrameLayout content = findViewById(R.id.content);
    fragmentStateManager = new FragmentStateManager(content, getSupportFragmentManager()) {
            @Override
            public Fragment getItem(int position) {
                switch (position) {
                    case 0:
                        return new MainFragment();
                    case 1:
                        return new SearchFragment();
                    case 2:
                        return new MeFragment();
                }
            }
        };
}

To change current fragment, call

fragmentStateManager.changeFragment(0); // 0 is the index of the fragment

Integration with BottomNavigationView

Add item selected listener

navigation.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem item) {
        int position = getNavPositionFromMenuItem(item);
        if (position != -1) {
            fragmentStateManager.changeFragment(getNavPositionFromMenuItem(item));
            return true;
        }

        return false;
    }
});

(Optional) Add item reselected listener. This will reset the fragment to it's original state

navigation.setOnNavigationItemReselectedListener(new BottomNavigationView.OnNavigationItemReselectedListener() {
    @Override
    public void onNavigationItemReselected(@NonNull MenuItem item) {
        int position = getNavPositionFromMenuItem(item);
        if (position != -1) {
            fragmentStateManager.removeFragment(position);
            fragmentStateManager.changeFragment(position);
        }
    }
});