Android Working with BottomNavigationView

/res/layout/activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="iterator.ir.a053.MainActivity">

    <android.support.design.widget.BottomNavigationView
        android:id="@+id/bottomNavigationView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        app:itemBackground="@android:color/holo_green_light"
        app:itemIconTint="@android:color/white"
        app:itemTextColor="@android:color/black"
        app:menu="@menu/navigation_menu">

    </android.support.design.widget.BottomNavigationView>

</RelativeLayout>

/res/menu/navigation_menu.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:android="http://schemas.android.com/apk/res/android">

    <item
        android:id="@+id/itemAdd"
        android:checkable="false"
        android:enabled="true"
        android:icon="@drawable/ic_add"
        android:title="Add"
        android:visible="true"
        app:showAsAction="ifRoom" />
    <item
        android:id="@+id/itemEdit"
        android:checkable="false"
        android:enabled="true"
        android:icon="@drawable/ic_edit"
        android:title="Edit"
        android:visible="true"
        app:showAsAction="ifRoom" />
    <item
        android:id="@+id/itemDelete"
        android:checkable="false"
        android:enabled="true"
        android:icon="@drawable/ic_delete"
        android:title="Delete"
        android:visible="true"
        app:showAsAction="ifRoom" />
</menu>

/res/drawable/nav_item_color_state.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@color/white" android:state_enabled="true" />
    <item android:drawable="@color/gray" android:state_enabled="false" />
</selector>

MainActivity.java

public class MainActivity extends AppCompatActivity {

    BottomNavigationView bottomNavigationView;

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

        bottomNavigationView= (BottomNavigationView) findViewById(R.id.bottomNavigationView);

        bottomNavigationView.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {

                item.setChecked(true);

                switch (item.getItemId())
                {
                    case R.id.itemAdd:
                        Toast.makeText(MainActivity.this,"Add",Toast.LENGTH_SHORT).show();
                        break;
                    case R.id.itemEdit:
                        Toast.makeText(MainActivity.this,"Edit",Toast.LENGTH_SHORT).show();
                        break;
                    case R.id.itemDelete:
                        Toast.makeText(MainActivity.this,"Delete",Toast.LENGTH_SHORT).show();
                        break;
                }

                return true;
            }
        });
    }
}

References
https://github.com/mhdr/AndroidSamples/tree/master/053
https://www.youtube.com/watch?v=wcE7IIHKfRg
https://developer.android.com/reference/android/support/design/widget/BottomNavigationView.html
https://medium.com/@hitherejoe/exploring-the-android-design-support-library-bottom-navigation-drawer-548de699e8e0#.8sgxtnkhb