How to add an item to a menu group in NavigationView

Question

In a word game for Android I currently have a hardcoded menu inflated from left_drawer_menu.xml and consisting of 3 groups (my turn, opponent turn and finally other stuff):

mLeftDrawer = (NavigationView) findViewById(R.id.left_drawer);
mLeftDrawer.setNavigationItemSelectedListener(
        new NavigationView.OnNavigationItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(final MenuItem menuItem) {
                Menu menu = mLeftDrawer.getMenu();

                if (menuItem.getGroupId() == R.id.my_move) {
                    menu.setGroupCheckable(R.id.my_move, true, true);
                    menu.setGroupCheckable(R.id.his_move, false, false);
                    menu.setGroupCheckable(R.id.extras, false, false);
                } else if (menuItem.getGroupId() == R.id.his_move) {
                    menu.setGroupCheckable(R.id.my_move, false, false);
                    menu.setGroupCheckable(R.id.his_move, true, true);
                    menu.setGroupCheckable(R.id.extras, false, false);
                } else if (menuItem.getGroupId() == R.id.extras) {
                    menu.setGroupCheckable(R.id.my_move, false, false);
                    menu.setGroupCheckable(R.id.his_move, false, false);
                    menu.setGroupCheckable(R.id.extras, true, true);
                }

                menuItem.setChecked(true);
                mLeftItem = menuItem.getItemId();
                mDrawerLayout.closeDrawer(mLeftDrawer);
                mHandler.postDelayed(new Runnable() {
                    @Override
                    public void run() {
                        if (mLeftItem == R.id.start) {
                            startNewGame();
                        } 
                    }
                },DRAWER_CLOSE_DELAY);

                return true;
            }
        });

Now I am trying to change that menu dynamically.

I have SQLite instance containing all game data and use IntentService to read/write the database - that part works fine.

My current difficulty is: with the following code, the new items are added outside the R.id.my_move group:

if (mLeftItem == R.id.start) {
    startNewGame();

    Random r = new Random();
    int i = r.nextInt(100);
    menu.add(R.id.my_move, i, i, "Item " + i);   // why is my_move ignored?
} 

UPDATE:

As a further test I have tried assigning even and not even items to 2 separate groups with this code:

Random r = new Random();
int i = r.nextInt(100);
int group = 1 + (i % 2); // can be 1 or 2
menu.add(group, i, i, "Item " + i);

However the result looks chaotic:

Also I have discovered the (probably already fixed?) Issue 176300 and wonder if maybe sub-menus should be better used instead of menu groups?

Answer 1

On checking MenuItemImpl source code

     ...
     *    @param group Item ordering grouping control. The item will be added after
     *            all other items whose order is <= this number, and before any
     *            that are larger than it. This can also be used to define
     *            groups of items for batch state changes. Normally use 0.
     ...

    MenuItemImpl(MenuBuilder menu, int group, int id, int categoryOrder, int ordering,
        CharSequence title, int showAsAction) {

So you should define ordering in your xml (give same order to items in one group and increment in each following group)

<menu xmlns:android="http://schemas.android.com/apk/res/android">

    <group android:id="@+id/my_move" android:checkableBehavior="single">
        <item
            android:orderInCategory="0"
            android:id="@+id/game1"
            android:icon="@drawable/ic_stars_black_24dp"
            android:title="Game #1" />
        <item
            android:orderInCategory="0"
            android:id="@+id/game2"
            android:icon="@drawable/ic_stars_black_24dp"
            android:title="Game #2" />
    </group>
    <group android:id="@+id/his_move" android:checkableBehavior="single">
        <item
            android:orderInCategory="1"
            android:id="@+id/game5"
            android:icon="@drawable/ic_clock_black_24dp"
            android:title="Game #5" />
        <item
            android:orderInCategory="1"
            android:id="@+id/game6"
            android:icon="@drawable/ic_clock_black_24dp"
            android:title="Game #6" />
        <item
            android:orderInCategory="1"
            android:id="@+id/game7"
            android:icon="@drawable/ic_clock_black_24dp"
            android:title="Game #7" />
    </group>
    .....

</menu>

and give an appropriate order value while adding the item in your code. So if you want to add the item at the end of first group, add it as:

menu.add(R.id.my_move, Menu.NONE, 0, "Item1");

and if you want to add to second group, add it as:

menu.add(R.id.his_move, Menu.NONE, 1, "Item2");

The problem with your code could be that all items in the xml have default orderInCategory 0 and so the new item gets added after all these items.

UPDATE

To add icon use setIcon method for MenuItem

menu.add(R.id.my_move, Menu.NONE, 0, "Item1").setIcon(R.drawable.ic_stars_black_24dp);