添加导航栏后 TabLayout 不显示选项卡

Question

我正在使用 ViewPager + TabLayout。它工作正常，但在我添加导航栏后，TabLayout 没有显示选项卡。我寻找解决方案，但没有一个有帮助。如果有人告诉我为什么会发生这种情况，那将非常有帮助。

MainActivity.java

    ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);

    SimpleFragmentPageAdapter adapter = new SimpleFragmentPageAdapter(this, getSupportFragmentManager());

    viewPager.setAdapter(adapter);

    TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);

    tabLayout.setupWithViewPager(viewPager);

    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.addDrawerListener(toggle);
    toggle.syncState();

    NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
    navigationView.setNavigationItemSelectedListener(this);

content_main.xml

    <android.support.design.widget.TabLayout
    android:id="@+id/tabs"
    style="@style/CategoryTab"
    android:background="@color/colorPrimary"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:tabTextColor="#ddd"
    app:tabSelectedTextColor="#fff" />

    <android.support.v4.view.ViewPager
    android:id="@+id/viewpager"
    android:background="#fff"
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>

Answer 1

请参考此代码。在 appbar 布局中添加选项卡布局。试试这个

<android.support.design.widget.AppBarLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginTop="200dp"
    android:id="@+id/appBarLayout2">


    <android.support.design.widget.TabLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/tabLayout2"
        app:tabMode="fixed"
        app:tabGravity="fill"

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

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

<android.support.v4.view.ViewPager
    android:layout_width="match_parent"
    android:layout_height="300dp"
    android:layout_alignParentStart="true"
    android:layout_alignParentBottom="true"
    android:id="@+id/viewPager2"
    android:layout_below="@+id/appBarLayout2">

</android.support.v4.view.ViewPager>