我想在片段中制作地图，我在谷歌的教程中尝试，然后我发现了一些错误。我尝试在堆栈溢出中搜索它但仍然无法/没有找到答案所以我需要你的帮助伙伴为什么这个错误发生我想知道我的代码是错的
所以这里是我的代码：
package qualitas.co.id.projectdelivery.fragment;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
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;
import java.util.ArrayList;
import java.util.List;
import qualitas.co.id.projectdelivery.MainActivity;
import qualitas.co.id.projectdelivery.R;
import qualitas.co.id.projectdelivery.adapter.MyAdapter;
import qualitas.co.id.projectdelivery.model.RetailModel;
public class FragmentMap extends Fragment {
private static View view;
/**
* Note that this may be null if the Google Play services APK is not
* available.
*/
private static GoogleMap mMap;
private static Double latitude, longitude;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
if (container == null) {
return null;
}
view = (RelativeLayout) inflater.inflate(R.layout.mapfragment, container, false);
// Passing harcoded values for latitude & longitude. Please change as per your need. This is just used to drop a Marker on the Map
latitude = 26.78;
longitude = 72.56;
setUpMapIfNeeded(); // For setting up the MapFragment
return view;
}
public 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) getChildFragmentManager()
.findFragmentById(R.id.location_map)).getMap();
/* 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));
}
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
// TODO Auto-generated method stub
if (mMap != null)
setUpMap();
if (mMap == null) {
// Try to obtain the map from the SupportMapFragment.
mMap = ((SupportMapFragment) MainActivity.fragmentManager
.findFragmentById(R.id.location_map)).getMap(); // getMap is deprecated
// Check if we were successful in obtaining the map.
if (mMap != null)
setUpMap();
}
}
/**** 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;
}
}
}
这里布局：
<?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" >
<fragment
android:id="@+id/location_map"
android:layout_width="match_parent"
android:layout_height="match_parent"
class="com.google.android.gms.maps.SupportMapFragment" />
</RelativeLayout>
错误：
03-17 09:03:19.163 28682-28682/qualitas.co.id.projectdelivery E/AndroidRuntime: FATAL EXCEPTION: main
Process: qualitas.co.id.projectdelivery, PID: 28682
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
at qualitas.co.id.projectdelivery.fragment.FragmentMap.setUpMapIfNeeded(FragmentMap.java:59)
at qualitas.co.id.projectdelivery.fragment.FragmentMap.onCreateView(FragmentMap.java:49)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:1974)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1067)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1252)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:738)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1617)
at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:517)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:6117)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)
有人可以帮助我吗？
答案 0 :(得分：2)
改变这个：
mMap = ((SupportMapFragment) getChildFragmentManager()
.findFragmentById(R.id.location_map)).getMap();
用这个：
mMap = ((SupportMapFragment) getActivity().getSupportFragmentManager()
.findFragmentById(R.id.location_map)).getMap();