SupportMapFragment的的GetMap（）返回null [英] SupportMapFragment's getMap() returns null

问题描述

我想一个 SupportMapFragment 动态创建，并把它放在一个的FrameLayout 容器

我的问题是， mMapFragment.getMap（）返回空 ...

任何人都可以帮忙吗？

CenterMapFragment.java

 公共类CenterMapFragment扩展片段{

    私人SupportMapFragment mMapFragment;

    @覆盖
    公共查看onCreateView（LayoutInflater充气，容器的ViewGroup，捆绑savedInstanceState）{

        返回inflater.inflate（R.layout.center_map_fragment，集装箱，假）;
    }

    @覆盖
    公共无效onActivityCreated（包savedInstanceState）{
        super.onActivityCreated（savedInstanceState）;

        如果（GooglePlayServicesUtil.isGooglePlayServicesAvailable（getActivity（））== ConnectionResult.SUCCESS）{
            setUpMapIfNeeded（）;
        }
    }


    私人无效setUpMapIfNeeded（）{

        如果（mMapFragment == NULL）{

            mMapFragment = SupportMapFragment.newInstance（）;
            FragmentTransaction fragmentTransaction =
                            。getChildFragmentManager（）的BeginTransaction（）;
            fragmentTransaction.replace（R.id.map，mMapFragment）;
            fragmentTransaction.commit（）;

            setUpMap（）;
        }
    }

    私人无效setUpMap（）{

        GoogleMap的地图= mMapFragment.getMap（）;

        //地图为空！

    }

    @覆盖
    公共无效onResume（）
    {
        super.onResume（）;
        setUpMapIfNeeded（）;
    }
}
 

center_map_fragment.xml

 ＆LT; XML版本=1.0编码=UTF-8＆GT？;
＆LT; RelativeLayout的的xmlns：机器人=htt​​p://schemas.android.com/apk/res/android
    机器人：layout_width =match_parent
    机器人：layout_height =match_parent＆GT;

    ＆LT;的FrameLayout
        机器人：ID =@ + ID /图
        机器人：layout_width =match_parent
        机器人：layout_height =match_parent＆GT;
    ＆LT; /的FrameLayout＆GT;

    ＆LT;按钮
        机器人：ID =@ + ID / btn_loc
        机器人：layout_width =60dp
        机器人：layout_height =50dp
        机器人：layout_alignParentBottom =真
        机器人：layout_alignParentRight =真
        机器人：背景=@可绘制/ locbtn/＆GT;

＆LT; / RelativeLayout的＆GT;
 

解决方案

提交（）在 FragmentTransaction 做不立即执行的操作。到时候你叫 setUpMap（）， onCreateView（）不会一直呼吁 SupportMapFragment ，因此有 将尚未是地图。

一种方法是不使用嵌套的片段，选举，而不是有 CenterMapFragment 延长 SupportMapFragment ，在这种情况下的GetMap（）在 onCreateView应该工作的任何时间（）（例如， onActivityCreated（））。

I'm trying to create a SupportMapFragment dynamically and to put it in a FrameLayout container.

My issue is that mMapFragment.getMap() returns null...

Anybody can help?

CenterMapFragment.java

public class CenterMapFragment extends Fragment {

    private SupportMapFragment mMapFragment;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        return inflater.inflate(R.layout.center_map_fragment, container, false);
    }

    @Override
    public void onActivityCreated (Bundle savedInstanceState){
        super.onActivityCreated(savedInstanceState);

        if (GooglePlayServicesUtil.isGooglePlayServicesAvailable(getActivity()) == ConnectionResult.SUCCESS) {
            setUpMapIfNeeded();
        }
    }


    private void setUpMapIfNeeded() {

        if (mMapFragment == null) {

            mMapFragment = SupportMapFragment.newInstance();
            FragmentTransaction fragmentTransaction =
                            getChildFragmentManager().beginTransaction();
            fragmentTransaction.replace(R.id.map, mMapFragment);
            fragmentTransaction.commit(); 

            setUpMap();
        }
    }

    private void setUpMap() {       

        GoogleMap map = mMapFragment.getMap();  

        // map is null!

    }

    @Override
    public void onResume()
    {
        super.onResume();
        setUpMapIfNeeded();     
    }
}

center_map_fragment.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <FrameLayout
        android:id="@+id/map"
        android:layout_width="match_parent"
        android:layout_height="match_parent" >
    </FrameLayout>

    <Button
        android:id="@+id/btn_loc"
        android:layout_width="60dp"
        android:layout_height="50dp"
        android:layout_alignParentBottom="true"
        android:layout_alignParentRight="true"
        android:background="@drawable/locbtn" />

</RelativeLayout>

解决方案

commit() on a FragmentTransaction does not perform its operations immediately. By the time you call setUpMap(), onCreateView() will not have been called on the SupportMapFragment, and hence there will not yet be a map.

One approach is to not use nested fragments, electing instead to have CenterMapFragment extend SupportMapFragment, in which case getMap() should work any time after onCreateView() (e.g., onActivityCreated()).

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