android - 如何显示子 fragment 工具栏的后退箭头

Question

我有一个包含很多 fragment 的主要 Activity ，主要 Activity 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>

当我将页面切换到下一个 fragment 时，我希望该 fragment 在工具栏上有一个后退箭头，它可以返回上一个 Activity ，也许是 fragment 。

我尝试在主要 Activity 上设置功能:

public void setBackArrow() {
    toolbar.setNavigationIcon(R.drawable.nav_icon_arrow_18x18_white);
    toolbar.setNavigationOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            switchFragment(NewsInformation.newInstance());
        }
    });
}

我的开关函数:

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 fragment 中这样调用它:

    @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 fragment ，然后先点击返回。

但我遇到的问题是当我回到以前的布局时，我失去了原来的工具栏菜单功能，void setBackArrow() 替换它，并且导航图标始终是 R.drawable.nav_icon_arrow_18x18_white。

让我的子 fragment 具有后退箭头并且它可以更改为以前的布局的最佳方法是什么？

Answer 1

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(); 

在 fragment 附加/switchFragment 完成后设置下面的代码

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

onBackButtonHit()

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

string.xml

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

ma​​inLayout.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>