Android 如何显示子片段工具栏的返回箭头

我有一个主要活动包含很多片段，主要活动布局如下：

<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/drawerLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.user.taiwandigestionsociety_v11.MainActivity">


    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#FFFFFF">

//----------------------here is my toolbar------------------------
<include layout="@layout/toolbar"/>

        <FrameLayout
            android:id="@+id/mainFrame"
            android:layout_gravity="end"
            android:layout_width="match_parent"
            android:layout_height="match_parent">

        </FrameLayout>

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


    <android.support.design.widget.NavigationView
        android:id="@+id/nav_view"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:background="@android:color/transparent"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header">
    </android.support.design.widget.NavigationView>


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

    @Override
      public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                     Bundle savedInstanceState) {
      View view =inflater.inflate(R.layout.activity_list_fragment,container, false);
//try to let the fragment has a back arrow toolbar , and has the onClick to previous layout     
      ((MainActivity) getActivity()).setBackArrow();

      return view;
      }

我的开关功能：

private void switchFragment(Fragment fragment) {
        FragmentManager manager = getActivity().getSupportFragmentManager();
        FragmentTransaction transaction = manager.beginTransaction();
        transaction.replace(R.id.mainFrame, fragment, null);
        //transaction.addToBackStack(null);
        transaction.commit();
    }

我在下一个片段中这样称呼它：

<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/drawerLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.user.taiwandigestionsociety_v11.MainActivity">


    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#FFFFFF">

//----------------------here is my toolbar------------------------
<include layout="@layout/toolbar"/>

        <FrameLayout
            android:id="@+id/mainFrame"
            android:layout_gravity="end"
            android:layout_width="match_parent"
            android:layout_height="match_parent">

        </FrameLayout>

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


    <android.support.design.widget.NavigationView
        android:id="@+id/nav_view"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:background="@android:color/transparent"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header">
    </android.support.design.widget.NavigationView>


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

    @Override
      public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                     Bundle savedInstanceState) {
      View view =inflater.inflate(R.layout.activity_list_fragment,container, false);
//try to let the fragment has a back arrow toolbar , and has the onClick to previous layout     
      ((MainActivity) getActivity()).setBackArrow();

      return view;
      }

我可以切换到下一个片段，然后首先单击返回

但我遇到的问题是，当我回到以前的布局时，我丢失了原来的工具栏菜单函数，将其替换为void setBackArrow（），导航图标始终为R.drawable.nav_Icon_arrow_18x18_白色

---

让我的子片段具有返回箭头并可以更改为以前的布局的最佳方法是什么？

使用

AppCompatActivity

而不是

Activity

以下步骤描述了总体思路

onCreate（）

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(); 

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

<resources>
    <string name="navigation_drawer_open">Open navigation drawer</string>
    <string name="navigation_drawer_close">Close navigation drawer</string>
</resources>

在附加片段/切换片段完成后设置以下代码

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(); 

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

<resources>
    <string name="navigation_drawer_open">Open navigation drawer</string>
    <string name="navigation_drawer_close">Close navigation drawer</string>
</resources>

onBackButtonHit（）

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

string.xml

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(); 

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

<resources>
    <string name="navigation_drawer_open">Open navigation drawer</string>
    <string name="navigation_drawer_close">Close navigation drawer</string>
</resources>

打开导航抽屉
关闭导航抽屉

mainLayout.xml

<?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
       <!-- AppBarLayout -->
       <!-- Fragment holer etc..--> />

    <android.support.design.widget.NavigationView
        android:id="@+id/nav_view"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header_main"
        app:menu="@menu/activity_main_drawer" />

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

/>