Android 工具栏上的图标不显示'；t打开导航抽屉并且不'；不要在滚动时自动消失

我正在尝试与选项卡一起实现NavigationView。 下面是活动代码：

public class DashBoardActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {

    private Toolbar toolbar;
    private ViewPager viewPager;
    private TabLayout tabLayout;
    private ActionBarDrawerToggle toggle;
    private NavigationView navigationView;
    private DrawerLayout drawer;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.main_activity);

        init();

        decorate();

        setListeners();
    }

    private void init() {
        toolbar = (Toolbar) findViewById(R.id.toolbar);
        viewPager = (ViewPager) findViewById(R.id.viewpager);
        tabLayout = (TabLayout) findViewById(R.id.tabs);
        drawer = (DrawerLayout) findViewById(R.id.drawer_layout);

        toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);

        navigationView = (NavigationView) findViewById(R.id.nav_view);
    }

    private void decorate() {
        setSupportActionBar(toolbar);
        setupViewPager(viewPager);
        tabLayout.setupWithViewPager(viewPager);
        toggle.syncState();
    }

    private void setListeners() {
        drawer.setDrawerListener(toggle);
    }

    private void setupViewPager(ViewPager viewPager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getFragmentManager());
        adapter.addFrag(new EventsFragment(), getString(R.string.all_events_tab));
        adapter.addFrag(new EventsFragment(), getString(R.string.soon_tab));
        viewPager.setAdapter(adapter);
    }

    @Override
    public boolean onNavigationItemSelected(MenuItem item) {

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

和main_activity.xml层次结构：

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout 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"
    android:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:openDrawer="start">

    <include
        layout="@layout/app_bar_main"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

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

</android.support.v4.widget.DrawerLayout>

app\u bar\u main.xml：

<?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"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:context=".activities.DashBoardActivity">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            app:layout_scrollFlags="scroll|enterAlways|snap"
            app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />

        <android.support.design.widget.TabLayout
            android:id="@+id/tabs"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />

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

    <android.support.v4.view.ViewPager
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />

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

---

有两个问题：

工具栏上的汉堡图标无法打开导航抽屉

滚动时工具栏不会消失

我在实施过程中遗漏了什么？原因可能是什么

---

谢谢

将这段代码添加到解决汉堡图标问题的活动中

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
       case android.R.id.home:
            mDrawerLayout.openDrawer(GravityCompat.START);  // OPEN DRAWER
            return true;
        ....
    }
    return super.onOptionsItemSelected(item);
}

对于工具栏部分，您是否尝试过像这样放置布局\u滚动标记

<android.support.v7.widget.Toolbar
                 ...
                 app:layout_scrollFlags="scroll|enterAlways"/>

谢谢你的回答

.openDrawer（GravityCompat.START）

起作用，但

滚动|始终输入“

标志对我没有帮助。@MarkKorzhov我不知道你想要什么样的行为。但是，请按照此操作并将

layout\u scrollFlag

的类型设置为您想要显示完整的app\u bar\u main.xml吗？@GPack已在帖子中进行了更改。是否尝试不使用snap flag？是，我尝试了大量不同的组合：）我认为问题可能在于ViewPager的内容片段：必须有一个实现NestedScrollingChild接口的视图，如RecyclerView或NestedScrollView