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

     <group android:checkableBehavior="single">

         <item

                 android:id="@+id/contact_us"

                 android:orderInCategory="1"

                 android:showAsAction=""

                 android:title="联系我们"/>

         <item android:title="关于我们"/>

     </group>

    <group>

        <item android:title="系统设置"

              android:orderInCategory="2"

              android:icon="@drawable/ic_launcher"

              android:id="@+id/system_setting"

                >

            <menu>

                <item android:title="亮度设置" android:id="@+id/liangdu"/>

                <item android:enabled="false" android:title="主题设置" android:id="@+id/theme"/>

            </menu>

        </item>

    </group>

</menu>

 @Override

    public boolean onCreateOptionsMenu(Menu menu) {

        new MenuInflater(this).inflate(R.menu.option_menu_main, menu);

        return super.onCreateOptionsMenu(menu);

    }

    @Override

    public boolean onOptionsItemSelected(MenuItem item) {

        switch (item.getItemId()) {

            case R.id.liangdu:

                Toast.makeText(this, "点击了亮度", 1).show();

                startActivity(new Intent(this, LiangduActivity.class));

                break;

            case R.id.contact_us:

                Toast.makeText(this, "点击了关于我们", 1).show();

                break;

        }

        return true;

    }