有没有办法在片段中显示活动

Question

我在我的地图应用程序中使用导航抽屉，我设法在主页上显示地图。遇到的问题是我无法将地图片段（在布局“xml”中）连接到 MapsActivity（java 文件）。

我尝试使用MapsActivity extends Fragment 而不是MapsActivity extends FragmentActivity，但这当然行不通。

主要的xml布局：

<!-- A DrawerLayout is intended to be used as the top-level content view using match_parent for both width and height to consume the full space available. -->
<android.support.v4.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">

<!-- As the main content view, the view below consumes the entire
     space available using match_parent in both dimensions. -->
<FrameLayout android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent">


 <!-- *****The problem I am having is in the following fragment could not link it to the MapsActivity-->
 <fragment
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:id="@+id/map"
        tools:context=".MapsActivity"
        android:name="com.google.android.gms.maps.SupportMapFragment"/>


</FrameLayout>


<!-- android:layout_gravity="start" tells DrawerLayout to treat
     this as a sliding drawer on the left side for left-to-right
     languages and on the right side for right-to-left languages.
     If you're not building against API 17 or higher, use
     android:layout_gravity="left" instead. -->
<!-- The drawer is given a fixed width in dp and extends the full height of
     the container. -->
<fragment android:id="@+id/navigation_drawer"
    android:layout_width="@dimen/navigation_drawer_width"
    android:layout_height="match_parent"
    android:layout_gravity="start"
    android:name="com.example.famfelimban.mydiet.NavigationDrawerFragment"
    tools:layout="@layout/fragment_navigation_drawer" />

但是，我有一个单独的地图 xml 布局，它工作正常 与 MapsActivity 配合使用的 activity_maps.xml

<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"/>

地图活动

    public class MapsActivity extends FragmentActivity {

    private GoogleMap mMap; // Might be null if Google Play services APK is not available.

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

    @Override
    protected void onResume() {

    }

    private void setUpMapIfNeeded() {

    }

    private void setUpMap() {

    }
}

Answer 1

不，Activitys 是 Fragments 的持有者，Fragments 不能持有活动。

这个问题可能很有趣：How to show different Activities in Fragment implementation?

Answer 2

您在这里要做的是将您的Activity 代码移植到Fragment。这并不难，一个片段具有几乎相同的生命周期。唯一的区别是，不是在onCreate 中抓取和修改Views，而是需要在onCreateView 中进行，并且需要实现static newInstance() 方法。

将 xml 中的 FrameLayout 留空。只有FragmentManager 才能将片段膨胀到其中。对代码的两处更改

在Activity

@Override
protected void onStart() {
    super.onStart();

    Fragment mapFragment = MapFragment.newInstance(/*args*/);
    getFragmentManager()  //you may need getSupportFragmentMananger()
            .beginTransaction()
            .replace(R.id.container, mapFragment)
            .commit()
    //this inflates the Fragment into the FrameLayout
}

并创建一个Fragment，其功能类似于您的Activity 版本

public class MapFragment extends Fragment {
    ...
    public MapFragment() {/*should be empty*/}
    ...
    public static MapFragment newInstance(/*args*/) {
        Fragment fragment = new MapFragment();

        Bundle args = new Bundle();
        //put whatever information you need for your activity to run here
        fragment.setArguments(args);
        return fragment;
    }
    ...
    @Overide
    public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle savedInstanceState) {
        //this basically takes the place of onCreate in the Activity version
        View root = inflater.inflate(R.layout.fragment_map, parent);

        View yourView = root.findViewById(R.id.your_view);
        ...
        return root;
    }
    ...
}

祝你好运。