android - 如何在抽屉导航 Activity fragment 中正确使用谷歌地图 fragment

Question

我试图将 Google map fragment 放入我的应用程序中，但当我尝试在 Locations 类中扩充 View 时，我不断收到此错误:

android.view.InflateException: Binary XML file line #37: Binary XML file line #37: Error inflating class fragment
Caused by: android.view.InflateException: Binary XML file line #37: Error inflating class fragment
Caused by: android.app.Fragment$InstantiationException: Trying to instantiate a class com.google.android.gms.maps.SupportMapFragment that is not a Fragment

---

我想将 map fragment 放在另一个 fragment 中，并使用抽屉导航加载到主 Activity 中。

这是我加载 map 应该进入的位置 fragment 的代码:

@Override
    public boolean onNavigationItemSelected(MenuItem item) {
        // Handle navigation view item clicks here.
        int id = item.getItemId();
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);

        Fragment fragment = new Race();
        toolbar.setTitle(R.string.nav_name_race);
        FragmentManager fragmentManager = getFragmentManager();

        if (id == R.id.nav_race) {
            toolbar.setTitle(R.string.nav_name_race);
            fragment = new Race();
        } else if (id == R.id.nav_pilot) {
            toolbar.setTitle(R.string.nav_name_pilot);
            fragment = new Pilot();
        } else if (id == R.id.nav_locations) {
            toolbar.setTitle(R.string.nav_name_locations);
            fragment = new Locations();
        } else if (id == R.id.nav_channelpicker) {
            toolbar.setTitle(R.string.nav_name_channelpicker);
            fragment = new Channelpicker();
        } else if (id == R.id.nav_band_overview) {
            toolbar.setTitle(R.string.nav_name_band_overview);
            fragment = new BandOverview();
        }

        fragmentManager.beginTransaction()
                .replace(R.id.mainframelayout, fragment)
                .commit();


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

位置类:

public class Locations extends Fragment implements OnMapReadyCallback {

    private View view;
    private GoogleMap map;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        this.view = inflater.inflate(R.layout.content_locations, container, false);
        SupportMapFragment mapFragment = (SupportMapFragment) (((FragmentActivity) getActivity()).getSupportFragmentManager().findFragmentById(R.id.map));
        mapFragment.getMapAsync(this);


        //set fab onClickListener
        FloatingActionButton fabtop = (FloatingActionButton) view.findViewById(R.id.fabtop);
        assert fabtop != null;
        fabtop.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Toast.makeText(view.getContext(), "top", Toast.LENGTH_SHORT).show();
            }
        });

        FloatingActionButton fabbottom = (FloatingActionButton) view.findViewById(R.id.fabbottom);
        assert fabbottom != null;
        fabbottom.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Toast.makeText(view.getContext(), "bottom", Toast.LENGTH_SHORT).show();
            }
        });

        return this.view;
    }

    @Override
    public void onMapReady(GoogleMap googleMap)
    {
        map = googleMap;

        // Add a marker in Sydney and move the camera
        LatLng sydney = new LatLng(-34, 151);
        map.addMarker(new MarkerOptions().position(sydney).title("Marker in Sydney"));
        map.moveCamera(CameraUpdateFactory.newLatLng(sydney));
    }
}

布局文件:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:paddingTop="?android:attr/actionBarSize"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context=".MainActivity">

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fabtop"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="right|bottom"
        android:src="@drawable/ic_menu_mylocation"
        app:backgroundTint="#FFFFFF"
        android:layout_above="@+id/fabbottom"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:layout_marginRight="@dimen/fab_margin" />

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fabbottom"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="right|bottom"
        android:src="@mipmap/ic_add_white_48dp"
        android:layout_alignParentBottom="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:layout_margin="@dimen/fab_margin" />
    
    <fragment xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/map"
        tools:context=".MapsActivity"
        android:name="com.google.android.gms.maps.SupportMapFragment" />

</RelativeLayout>

我认为问题在于 fragment 中有一个 fragment ，因为如果我为 map 创建一个新的 Activity 一切正常。我仍然是使用 fragment 的初学者，不知道在我的应用程序中插入 map fragment 的正确方法。

感谢每个提示。

Answer 1

您不需要在 fragment 中调用 (SupportMapFragment) (((FragmentActivity) getActivity()).getSupportFragmentManager()，因为 getFragmentManager() 在 Fragment。但是当使用 Nested Fragments 时，您应该使用 getChildFragmentManager() 而不是 getFragmentManager()(参见 documentation)。

针对您的问题，您只需将代码更新为:

SupportMapFragment mapFragment = (SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.map);
if (mapFragment != null) {
    mapFragment.getMapAsync(this);
}

如果您遇到ID 重复、标记为空或父 ID 与 com.google.android.gms.maps.MapFragment 的另一个 fragment 等问题。您可以尝试讨论的任何解决方案 here .或者试试这个:

private View mContentView;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    if (mContentView == null) {
        mContentView = inflater.inflate(R.layout.content_locations, container, false);
    }
    return mContentView;
}

它不会每次都膨胀布局，因此您不会遇到重复 ID、标签 null 或父 ID 与另一个 fragment 的 com.google.android.gms.maps.MapFragment 问题。但是请确保您在 attachToRoot(inflater.inflate 的最后一个参数)中传递了 false，否则您可能会遇到类似指定的子项已经有一个父项的异常。