NavigationViewFragmentAdapters

A small library containing two adapters which allow for easy fragment management with a NavigationView or BottomNavigationView.

The library handles replacing the fragments and saving/restoring the fragment state, including showing the right fragment when opening an app again after it was killed.

Usage

First, decide which adapter suits your use case better.

The NavigationViewFragmentAdapter detaches fragments after another menu item is selected. This means that each Fragment for a menu item is kept in memory, but there is no overhead for recreating when it is attached again.

The NavigationViewStateFragmentAdapter saves the state and removes the fragment after another menu item is selected. This means that only the fragment for the current menu item is kept in memory, but there is overhead for recreating other fragments when they are selected again.

After you decided, create your adapter implementation:

private class MyNavigationViewAdapter extends NavigationViewFragmentAdapter {

    public MyNavigationViewAdapter(FragmentManager fragmentManager, @IdRes int containerId, @IdRes int defaultMenuItemId, Bundle savedInstanceState) {
        super(fragmentManager, containerId, defaultMenuItemId, savedInstanceState);
    }

    @NonNull
    @Override
    public Fragment getFragment(@IdRes int menuItemId) {
        switch (menuItemId) {
            case R.id.navitem_1:
                return SampleFragment.newInstance("Fragment 1");
            case R.id.navitem_2:
                return SampleFragment.newInstance("Fragment 2");
            case R.id.navitem_3:
                return SampleFragment.newInstance("Fragment 3");
            default:
                return SettingsFragment.newInstance();
        }
    }
}

Now, create an instance and attach it to your NavigationView in your Activity onCreate():

adapter = new MyNavigationViewAdapter(getSupportFragmentManager(), R.id.container, R.id.navitem_1, savedInstanceState);
adapter.attachTo(navigationView);

Also, don't forget to call adapter.onSaveInstanceState() in your Activity onSaveInstanceState().

Now you have your navigation drawer or bottom navigation view up and running, including state saving of the fragments.

Advanced Usage

OnNavigationItemSelectedListener

An additional OnNavigationItemSelectedListener can be provided via setNavigationItemSelectedListener(). This can be used to add behavior after the fragment transaction was commited. If you just want to close the drawer, the lib includes a CloseDrawerNavigationItemSelectedListener.

Back Stack

There are cases when some menu items (e.g. settings) should not simply replace the current fragment, but also be added to the back stack. To do this, override shouldAddToBackStack() in your adapter:

@Override
public boolean shouldAddToBackStack(@IdRes int menuItemId) {
    return menuItemId == R.id.navitem_settings;
}

Custom Actions

If you don't want to handle fragments when a menu item is selected (e.g. to start an Activity), you can override shouldHandleMenuItem() in your adapter:

@Override
public boolean shouldHandleMenuItem(@IdRes int menuItemId) {
    return menuItemId != R.id.navitem_sample_activity;
}

Don't forget to set an additional OnNavigationItemSelectedListener via setNavigationItemSelectedListener(), where you have to handle these menu items:

adapter.setNavigationItemSelectedListener(new CloseDrawerNavigationItemSelectedListener(drawerLayout) {
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        if(item.getItemId() == R.id.navitem_sample_activity) {
            startActivity(new Intent(MainActivity.this, SampleActivity.class));
        }

        return super.onNavigationItemSelected(item);
    }
});

Animations

You can provide custom animations for your fragment transactions via setCustomAnimations(). Separate animations can be set for when you add the transaction to the back stack via setBackStackCustomAnimations().

Sample

A basic sample app with example Activities for both adapters is available in the sample project.

Setup

The library is available on jCenter. Add the following to your build.gradle:

dependencies {
    compile 'com.patloew.navigationviewfragmentadapters:adapters:0.3.0'
}

License

Copyright 2016 Patrick Löwenstein

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.