Question

我一直在尝试将Google地图实现为一个viewpager片段，我已经遵循了许多不同的教程，但每次都惨遭失败。如果有人有任何煽动如何得到这样的工作，我会很高兴！以下是我使用的源代码：

的Src / MainActivity.java

public class MainActivity extends FragmentActivity {

    private PagerAdapter mPagerAdapter;
    public static FragmentManager fragmentManager;
    Context Map;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout._layout);
        inistialisePaging();

        //initialising the object of the FragmentManager.
        fragmentManager = getSupportFragmentManager();

    }

的Src / Map.java

package joe.wit.app.locophoto;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.RelativeLayout;

import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;

public class Map extends Fragment {



    private static GoogleMap mMap;
    private static Double latitude, longitude;
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {

        if(container == null){
            return null;

        }

        latitude = 26.78;
        longitude = 72.56;

        setUpMapIfNeeded(); // For setting up the MapFragment



        return (RelativeLayout) inflater.inflate(R.layout.map_layout, 
                container, false);  


    }

    /***** Sets up the map if it is possible to do so *****/
    public static 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) MainActivity.fragmentManager
                    .findFragmentById(R.id.location_map)).getMap();
            // Check if we were successful in obtaining the map.
            if (mMap != null)
                setUpMap();
        }
        }
        /**
         * This is where we can add markers or lines, add listeners or move the
         * camera.
         * <p>
         * This should only be called once and when we are sure that {@link #mMap}
         * is not null.
         */
        private static void setUpMap() {
            // For showing a move to my loction button
            mMap.setMyLocationEnabled(true);
            // For dropping a marker at a point on the Map
            mMap.addMarker(new MarkerOptions().position(new LatLng(latitude, longitude)).title("My Home").snippet("Home Address"));
            // For zooming automatically to the Dropped PIN Location
            mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(latitude,
                    longitude), 12.0f));
        }


        /**** The mapfragment's id must be removed from the FragmentManager
         **** or else if the same it is passed on the next time then 
         **** app will crash ****/
        @Override
        public void onDestroyView() {
            super.onDestroyView();
            if (mMap != null) {
                MainActivity.fragmentManager.beginTransaction()
                    .remove(MainActivity.fragmentManager.findFragmentById(R.id.location_map)).commit();
                mMap = null;
            }
        }
}

RES / map_layout.xml

 <?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="#00FF00"
    android:orientation="vertical" >

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

</RelativeLayout>

LOGCAT错误

02-26 13:34:25.176: E/AndroidRuntime(9065): FATAL EXCEPTION: main
02-26 13:34:25.176: E/AndroidRuntime(9065): Process: joe.wit.app.locophoto, PID: 9065
02-26 13:34:25.176: E/AndroidRuntime(9065): java.lang.NullPointerException: Attempt to invoke virtual method 'com.google.android.gms.maps.GoogleMap com.google.android.gms.maps.SupportMapFragment.getMap()' on a null object reference
02-26 13:34:25.176: E/AndroidRuntime(9065):     at joe.wit.app.locophoto.Map.setUpMapIfNeeded(Map.java:52)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at joe.wit.app.locophoto.Map.onCreateView(Map.java:36)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.support.v4.app.Fragment.performCreateView(Fragment.java:1786)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:947)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1126)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:739)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1489)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:486)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.support.v4.view.ViewPager.populate(ViewPager.java:1073)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.support.v4.view.ViewPager.populate(ViewPager.java:919)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1441)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.view.View.measure(View.java:17525)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:727)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:463)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.view.View.measure(View.java:17525)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5478)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:430)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.view.View.measure(View.java:17525)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5478)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at com.android.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:447)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.view.View.measure(View.java:17525)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5478)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:430)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2629)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.view.View.measure(View.java:17525)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2102)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1218)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1435)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1106)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6018)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.view.Choreographer$CallbackRecord.run(Choreographer.java:792)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.view.Choreographer.doCallbacks(Choreographer.java:596)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.view.Choreographer.doFrame(Choreographer.java:557)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:778)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.os.Handler.handleCallback(Handler.java:739)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.os.Handler.dispatchMessage(Handler.java:95)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.os.Looper.loop(Looper.java:155)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at android.app.ActivityThread.main(ActivityThread.java:5696)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at java.lang.reflect.Method.invoke(Native Method)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at java.lang.reflect.Method.invoke(Method.java:372)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1028)
02-26 13:34:25.176: E/AndroidRuntime(9065):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:823)

非常感谢任何帮助 问候乔

Answer 1

我不敢编译（不可动摇的类型：android.app.Fragment vs com.google.android.gms.maps.SupportMapFragment）。

这对我有用：

mMap = ((SupportMapFragment) ((FragmentActivity) getActivity()).getSupportFragmentManager().findFragmentById(R.id.location_map)).getMap();

Answer 2

尝试使用 getChildFragmentManager（）而不是 getFragmentManager（）。

像：

mMap = ((SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.map)).getMap();

{需要帮助!!} Google地图在Viewpager Fragment中

2 个答案: