更改我的自定义操作栏标题

嘿，有人请帮我更改我的工具栏标题对齐方式，我想将其设置为中心

并在标题下画一条长色线。

这是我的 xml 布局包含在活动布局中。

我的布局：

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 
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"
xmlns:ads="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.tiger.alahedclub.activity.navigation">



<android.support.design.widget.AppBarLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        app:titleTextColor="@android:color/black"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="@color/yellow"
        app:layout_scrollFlags="scroll|enterAlways"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />
    <android.support.design.widget.TabLayout
        android:id="@+id/tabs"
        android:background="@color/yellow"
        app:tabTextColor="@android:color/black"
        app:tabSelectedTextColor="@android:color/black"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:tabMode="fixed"
        app:tabGravity="fill"  />

 </android.support.design.widget.AppBarLayout>
 <android.support.v4.view.ViewPager
    android:id="@+id/viewpager"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/cardview_back"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"/>
<com.google.android.gms.ads.AdView
    android:id="@+id/adView"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_alignParentBottom="true"
    ads:adSize="SMART_BANNER"
    android:layout_gravity="bottom"
    ads:adUnitId="@string/banner_ad_unit_id">

</com.google.android.gms.ads.AdView>

我的活动课：

public class navigation extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener {
private TabLayout tabLayout;
private InterstitialAd mInterstitialAd;
private Button mNextLevelButton;
private TextView mTextView;
private ViewPager viewPager;
private int[] tabIcons = {
        R.drawable.ic_newsfeed,
        R.drawable.ic_livestream,
        R.drawable.ic_matches,
        R.drawable.ic_sort
};
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_navigation);


    MobileAds.initialize(getApplicationContext(), ""
    AdView mAdView = (AdView) findViewById(R.id.adView);
    AdRequest adRequest = new AdRequest.Builder().build();
    mAdView.loadAd(adRequest);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    if ((getIntent().getFlags() & Intent.FLAG_ACTIVITY_BROUGHT_TO_FRONT ) != 0) {
        // Activity was brought to front and not created,
        // Thus finishing this will get us to the last viewed activity
        finish();
        return;
    }

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
            this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
    drawer.setDrawerListener(toggle);
    toggle.syncState();

    NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
    navigationView.setNavigationItemSelectedListener(this);
    viewPager = (ViewPager) findViewById(R.id.viewpager);
    setupViewPager(viewPager);

    tabLayout = (TabLayout) findViewById(R.id.tabs);
    tabLayout.setupWithViewPager(viewPager);
    setupTabIcons();
}

private void setupTabIcons() {
    tabLayout.getTabAt(0).setIcon(tabIcons[0]);
    tabLayout.getTabAt(1).setIcon(tabIcons[1]);
    tabLayout.getTabAt(2).setIcon(tabIcons[2]);
 //   tabLayout.getTabAt(3).setIcon(tabIcons[3]);

}

private void setupViewPager(ViewPager viewPager) {
   ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
    adapter.addFrag(new OneFragment(),getString(R.string.newsfeed));
 //   adapter.addFrag(new TwoFragment(), getString(R.string.livestream));
    adapter.addFrag(new ThreeFragment(),getString(R.string.matches));
    adapter.addFrag(new FourFragment(),getString(R.string.schedule));
    viewPager.setAdapter(adapter);
}
class ViewPagerAdapter extends FragmentPagerAdapter {
    private final List<Fragment> mFragmentList = new ArrayList<>();
    private final List<String> mFragmentTitleList = new ArrayList<>();

    public ViewPagerAdapter(FragmentManager manager) {
        super(manager);
    }

    @Override
    public Fragment getItem(int position) {
        return mFragmentList.get(position);
    }

    @Override
    public int getCount() {
        return mFragmentList.size();
    }

    public void addFrag(Fragment fragment, String title) {
        mFragmentList.add(fragment);
        mFragmentTitleList.add(title);
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return mFragmentTitleList.get(position);
    }
}



@Override
public void onBackPressed() {

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    if (drawer.isDrawerOpen(GravityCompat.START)) {
        drawer.closeDrawer(GravityCompat.START);
    } else {

        super.onBackPressed();
    }
}






@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    int id = item.getItemId();

    if (id == R.id.share) {

     //share();

    } else if (id == R.id.check) {
       //check();

    } else if (id == R.id.rateus) {
       // rateMe();

    }

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}}

请问有什么建议吗？

更新：

我已将此文本视图添加到工具栏标签

<TextView
 android:id="@+id/action_bar_title"                 
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:text="@string/app_name"
            android:textColor="@android:color/black"
            android:textSize="24sp" />

但现在的问题是我得到了这个：

两个标题在同一个工具栏上被覆盖

更新 2：我想在应用程序标题下显示一行，如下图：