android - 试图将 map 放入 fragment Activity 中

Question

在我的 Android 应用程序中，我在扩展 Fragment 的类中显示 Google map map 。

目前，只显示 map ，但我无法从 SupportFragmentManager 获取 map 。

我所做的是使 Android Studio 中的 MapActivity 适应我的应用。

这是我的代码:

public class Tab2 extends Fragment {

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

    private double latitud_del_hotel, longitud_del_hotel;
    private String nombre_del_hotel;
    private GoogleMap map;

    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.tab_2, container, false);
        //setUpMapIfNeeded();
        return v;
    }

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


    }

    private void setUpMapIfNeeded() {
        // Do a null check to confirm that we have not already instantiated the map.
        if (mMap == null) {
            // Try to obtain the map from the SupportMapFragment.
            mMap = ((SupportMapFragment) getActivity().getSupportFragmentManager().findFragmentById(R.id.map))
                    .getMap();
            // Check if we were successful in obtaining the map.
            if (mMap != null) {
                setUpMap();
            }
        }
    }

    private void setUpMap() {
        mMap.addMarker(new MarkerOptions().position(new LatLng(0, 0)).title("Marker"));
    }

}

我遇到异常:java.lang.NullPointerException 在 com.solinpromex.elpasojuarezexperience.Tab2.setUpMapIfNeeded

我已经尝试从两种方法调用方法 setUpMapIfNeeded():onCreateView 和 onActivityCreated。两种情况都会抛出异常。

如果我删除 setUpMapIfNeeded()，则会显示 map ，但我想添加 map 对象。

欢迎任何帮助..

编辑

来自 logcat 的完整异常日志:

09-16 00:34:09.614  13999-13999/com.solinpromex.elpasojuarezexperience E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.solinpromex.elpasojuarezexperience, PID: 13999
    java.lang.NullPointerException
            at com.solinpromex.elpasojuarezexperience.Tab2.setUpMapIfNeeded(Tab2.java:66)
            at com.solinpromex.elpasojuarezexperience.Tab2.onActivityCreated(Tab2.java:57)
            at android.support.v4.app.Fragment.performActivityCreated(Fragment.java:1797)
            at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:979)
            at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1138)
            at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:740)
            at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1501)
            at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:490)
            at android.support.v4.app.FragmentStatePagerAdapter.finishUpdate(FragmentStatePagerAdapter.java:163)
            at android.support.v4.view.ViewPager.populate(ViewPager.java:1105)
            at android.support.v4.view.ViewPager.populate(ViewPager.java:951)
            at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1473)
            at android.view.View.measure(View.java:16857)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5378)
            at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1621)
            at android.widget.LinearLayout.measureVertical(LinearLayout.java:742)
            at android.widget.LinearLayout.onMeasure(LinearLayout.java:607)
            at android.view.View.measure(View.java:16857)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5378)
            at android.widget.FrameLayout.onMeasure(FrameLayout.java:340)
            at android.support.v7.internal.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:124)
            at android.view.View.measure(View.java:16857)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5378)
            at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1621)
            at android.widget.LinearLayout.measureVertical(LinearLayout.java:742)
            at android.widget.LinearLayout.onMeasure(LinearLayout.java:607)
            at android.view.View.measure(View.java:16857)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5378)
            at android.widget.FrameLayout.onMeasure(FrameLayout.java:340)
            at android.view.View.measure(View.java:16857)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5378)
            at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1621)
            at android.widget.LinearLayout.measureVertical(LinearLayout.java:742)
            at android.widget.LinearLayout.onMeasure(LinearLayout.java:607)
            at android.view.View.measure(View.java:16857)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5378)
            at android.widget.FrameLayout.onMeasure(FrameLayout.java:340)
            at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2332)
            at android.view.View.measure(View.java:16857)
            at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2271)
            at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1334)
            at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1532)
            at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1211)
            at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6282)
            at android.view.Choreographer$CallbackRecord.run(Choreographer.java:788)
            at android.view.Choreographer.doCallbacks(Choreographer.java:591)
            at android.view.Choreographer.doFrame(Choreographer.java:560)
            at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:774)
            at android.os.Handler.handleCallback(Handler.java:808)
            at android.os.Handler.dispatchMessage(Handler.java:103)
            at android.os.Looper.loop(Looper.java:193)
            at android.app.ActivityThread.main(ActivityThread.java:5299)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:825)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:641)
            at dalvik.system.NativeStart.main(Native Method)

编辑 2

布局文件tab_2

<?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">

    <LinearLayout
        android:orientation="vertical"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent">

        <fragment xmlns:android="http://schemas.android.com/apk/res/android"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:name="com.google.android.gms.maps.MapFragment"
            android:id="@+id/map"
            android:layout_alignParentTop="true"
            android:layout_alignParentBottom="true"
            android:layout_alignParentLeft="true"
            android:layout_alignParentRight="true" />
    </LinearLayout>
</RelativeLayout>

Answer 1

如果您使用最新的 GooglePlayServices，您可以使用 getMapAsync 函数，它会自动初始化 map 系统和 View 。

在布局中也使用MapView

这就是我在 fragment 中添加 map 的方式。

public class MapFragment extends Fragment implements OnMapReadyCallback {

     @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
            view = inflater.inflate(R.layout.fragment_tab_fragment1, container, false);

            FragmentManager manager = getFragmentManager();
            FragmentTransaction transaction = manager.beginTransaction();
            SupportMapFragment fragment = new SupportMapFragment();
            transaction.add(R.id.mapView, fragment);
            transaction.commit();

            fragment.getMapAsync(this);

            return view;
        }

   @Override
   public void onMapReady(GoogleMap map) {
      //map is ready
      map.addMarker(...
 }
}

在xml中

<com.google.android.gms.maps.MapView
    android:id="@+id/mapView"
    class="com.google.android.gms.maps.SupportMapFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

要使用最新的 GooglePlayService，请将其放入 gradle

compile 'com.google.android.gms:play-services:8.3.0'