Having two single-selection groups in ActionBar doesn't work, but attaching a pop up menu instead doesn't work either

问题

I am writing an Android app where the user must choose how and what to display on a graph. These options are expressed in two single-selection menu groups (radio buttons), both of which should be accessible from the action bar.

The first group works fine. It's added at the end of my ActionBar XML like this:

<group android:checkableBehavior="single" android:showAsAction="never" >
    <item android:id="@+id/menu_choice_1" android:title="Choice 1" />
    <item android:id="@+id/menu_choice_2" android:title="Choice 2" android:checked="true"/>
</group>

When I add a second <group> below the first one, however, the two merge into one single-selection list. In other words, the options from both lists are rendered together and if I choose an option pertaining to the first list, I cannot choose anything from the second.

Instead, I want two separate lists of radio buttons. My next idea was to add another button the ActionBar that, when clicked, would launch a pop-up menu. But when I click the button, I get an IllegalStateException, saying that my "MenuPopupHelper cannot be used without an anchor".

Here is my attempted pop-up menu code:

In my ActionBar XML:

<item android:id="@+id/menu_openothermenu"
  android:title="@string/openothermenustr"
  android:showAsAction="always" />

My new menu XML:

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <group android:checkableBehavior="single">
        <item android:id="@+id/menu_2_choice_1" android:title="@string/2_choice_1" />
        <item android:id="@+id/menu_2_choice_2" android:title="@string/2_choice_2" android:checked="true"/>
    </group>
</menu>

Code in my Activity:

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0);
    SharedPreferences.Editor editor;

    switch (item.getItemId()) {
    case R.id.openothermenu:
        Menu m = (Menu) findViewById(R.menu.other_menu);
        PopupMenu popup = new PopupMenu(this, findViewById(R.menu.main_menu));
        popup.setOnMenuItemClickListener(this);
        MenuInflater inflater = popup.getMenuInflater();
        inflater.inflate(R.menu.other_menu, popup.getMenu());
        /* This commented block doesn't work either, and prevents execution
        // Restore saved chosen value
        int chosen = settings.getInt(MENU_2_PREFS, -1);
        switch(chosen)
        {
            case 1:
                m.findItem(R.id.menu_1_choice_1).setChecked(true);
                updateVisibleThings();
                break;
            default:
            case 2:
                m.findItem(R.id.menu_2_choice_2).setChecked(true);
                updateOtherVisibleThings();
                break;
        }
        */
        popup.show();
        return true;
    default:
        return super.onOptionsItemSelected(item);
    }
}

@Override
public boolean onMenuItemClick(MenuItem item) {
    SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0);
    SharedPreferences.Editor editor;

    switch(item.getItemId()) {
    case R.id.menu_2_choice_1:
        if (item.isChecked()) item.setChecked(false);
        else item.setChecked(true);
        updateVisibleThings();

        // save chosen setting
        editor = settings.edit();
        editor.putInt(MENU_2_PREFS, 1);
        editor.commit(); // Commit the edits!

        return true;
    case R.id.menu_2_choice_2:
        if (item.isChecked()) item.setChecked(false);
        else item.setChecked(true);
        updateOtherVisibleThings();

        // save chosen setting
        editor = settings.edit();
        editor.putInt(MENU_2_PREFS, 2);
        editor.commit(); // Commit the edits!

        return true;
    default:
        return true;
    }
}

How can I create two sets of checkable menu items such that both are attached to the ActionBar?

回答1:

I found an elegant way to solve this that was unfortunately not in the documentation. Add the following code to your ActionBar menu XML:

<item android:id="@+id/menu_openothermenu"
      android:title="@string/openothermenustr"
      android:showAsAction="always">
    <menu>
        <group android:checkableBehavior="single">
            <item android:id="@+id/menu_2_choice_1" android:title="@string/2_choice_1"  android:showAsAction="never" />
            <item android:id="@+id/menu_2_choice_2" android:title="@string/2_choice_2"  android:showAsAction="never" android:checked="true" />
        </group>
     </menu>
</item>

No extra handler code or popup menu implementation is necessary for such a menu to appear.

来源：https://stackoverflow.com/questions/12505362/having-two-single-selection-groups-in-actionbar-doesnt-work-but-attaching-a-po