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社区首页 >问答首页 >碎片NullPointerException全球定位系统

问碎片NullPointerException全球定位系统
EN

Stack Overflow用户
提问于 2015-07-06 18:47:36
回答 3查看 307关注 0票数 1

我已经创建了一个操作栏导航选项卡布局，在其中一个选项卡中，我希望显示google并获取我的当前位置，我使用了LocationListener来获取位置，但这是重放错误，这是我的代码。

包装com.example.prototype.tabs；

代码语言：javascript
复制
import java.util.Timer;









import com.example.prototype.MainActivity;
import com.example.prototype.R;
import com.example.prototype.utility.GpsTracker;
import com.google.android.gms.maps.CameraUpdate;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.GoogleMapOptions;
import com.google.android.gms.maps.MapFragment;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.Circle;
import com.google.android.gms.maps.model.CircleOptions;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.Marker;
import com.google.android.gms.maps.model.MarkerOptions;

import android.support.v4.app.Fragment;
import android.app.FragmentManager;
import android.content.Context;
import android.graphics.Color;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;

public class NearByPlacesFragment extends Fragment  implements OnMapReadyCallback, LocationListener {

    GoogleMap gmap;
    Marker mp;
    LatLng ll;
    Location l;
    Context ctx=getActivity();
    double lat,lon;
    boolean isGpsEnabled,isNetworkAvailable,isLocationSet;
    LocationManager lmgr;
    long minTime = 60*1000*1;
    long minDistance = 10;
    Location loc;

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

        View rootView = inflater.inflate(R.layout.nearbyplaces, container, false);
         l=getLocation();
        if(l==null){Toast.makeText(getActivity(), "null", Toast.LENGTH_LONG).show();}
        SupportMapFragment mapFragment = (SupportMapFragment) getChildFragmentManager()
                    .findFragmentById(R.id.map);
            mapFragment.getMapAsync(this);

        return rootView;

    }



    @Override
    public void onMapReady(GoogleMap map) {
        // TODO Auto-generated method stub

            map.getUiSettings().setAllGesturesEnabled(true);
            map.setMapType(GoogleMap.MAP_TYPE_HYBRID);
            map.setMyLocationEnabled(true);
            if(l!=null)
            ll = new LatLng(l.getLatitude() , l.getLongitude());
            map.addMarker(new MarkerOptions().position(ll).title("Marker in Sydney"));


    }



     public Location getLocation(){

         lmgr=(LocationManager) ctx.getSystemService(Context.LOCATION_SERVICE);


         if(lmgr==null){Toast.makeText(getActivity(), "null manager", Toast.LENGTH_LONG).show();}


         isGpsEnabled=lmgr.isProviderEnabled(LocationManager.GPS_PROVIDER);
         isNetworkAvailable=lmgr.isProviderEnabled(LocationManager.NETWORK_PROVIDER);

         if(isGpsEnabled==true){
        setLocationManager("gps");
         }
         else if(isNetworkAvailable==true){
             setLocationManager("network");
          }



         return loc;




     }

     private boolean setLocationManager(String s){

         if(s.equals("gps")){

                lmgr.requestLocationUpdates(LocationManager.GPS_PROVIDER, minTime, minDistance, this);
                loc=lmgr.getLastKnownLocation(LocationManager.GPS_PROVIDER);        
         }

         else{

                lmgr.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, minTime, minDistance, this);
                loc=lmgr.getLastKnownLocation(LocationManager.GPS_PROVIDER);

         }


         return isLocationSet;
     }



    @Override
    public void onLocationChanged(Location location) {
        // TODO Auto-generated method stub

    }



    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
        // TODO Auto-generated method stub

    }



    @Override
    public void onProviderEnabled(String provider) {
        // TODO Auto-generated method stub

    }



    @Override
    public void onProviderDisabled(String provider) {
        // TODO Auto-generated method stub

    }








}

日志是：

代码语言：javascript
复制
07-07 00:05:02.424: E/dalvikvm(22824): Could not find class 'android.app.AppOpsManager', referenced from method com.google.android.gms.common.GooglePlayServicesUtil.zza
07-07 00:05:02.491: E/dalvikvm(22824): Could not find class 'android.app.AppOpsManager', referenced from method com.google.android.gms.common.ij.a
07-07 00:05:02.755: E/AndroidRuntime(22824): FATAL EXCEPTION: main
07-07 00:05:02.755: E/AndroidRuntime(22824): java.lang.NullPointerException
07-07 00:05:02.755: E/AndroidRuntime(22824):    at com.example.prototype.tabs.NearByPlacesFragment.getLocation(NearByPlacesFragment.java:92)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at com.example.prototype.tabs.NearByPlacesFragment.onCreateView(NearByPlacesFragment.java:62)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at android.support.v4.app.Fragment.performCreateView(Fragment.java:1789)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:955)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1138)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:740)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1501)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:490)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at android.support.v4.view.ViewPager.populate(ViewPager.java:1105)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at android.support.v4.view.ViewPager.setCurrentItemInternal(ViewPager.java:551)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at android.support.v4.view.ViewPager.setCurrentItemInternal(ViewPager.java:513)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at android.support.v4.view.ViewPager.setCurrentItem(ViewPager.java:494)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at com.example.prototype.MainActivity.onTabSelected(MainActivity.java:172)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at com.android.internal.app.ActionBarImpl.selectTab(ActionBarImpl.java:570)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at com.android.internal.app.ActionBarImpl$TabImpl.select(ActionBarImpl.java:1067)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at com.android.internal.widget.ScrollingTabContainerView$TabClickListener.onClick(ScrollingTabContainerView.java:519)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at android.view.View.performClick(View.java:4211)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at android.view.View$PerformClick.run(View.java:17446)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at android.os.Handler.handleCallback(Handler.java:725)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at android.os.Handler.dispatchMessage(Handler.java:92)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at android.os.Looper.loop(Looper.java:153)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at android.app.ActivityThread.main(ActivityThread.java:5297)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at java.lang.reflect.Method.invokeNative(Native Method)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at java.lang.reflect.Method.invoke(Method.java:511)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
07-07 00:05:02.755: E/AndroidRuntime(22824):    at dalvik.system.NativeStart.main(Native Method)
07-07 00:05:03.027: E/NativeCrypto(22824): ssl=0x60ac2588 cert_verify_callback x509_store_ctx=0x6151aab0 arg=0x0
07-07 00:05:03.027: E/NativeCrypto(22824): ssl=0x60ac2588 cert_verify_callback calling verifyCertificateChain authMethod=ECDHE_ECDSA
android
android-fragments
gps
location
EN

回答 3

Stack Overflow用户

回答已采纳

发布于 2015-07-06 18:59:00

主要的问题是，在进行此操作之前，您正在调用getActivity()：

代码语言：javascript
复制
 Context ctx=getActivity();

相反，在getActivity()中调用onCreateView()

代码语言：javascript
复制
public class NearByPlacesFragment extends Fragment  implements OnMapReadyCallback, LocationListener {

    GoogleMap gmap;
    Marker mp;
    LatLng ll;
    Location l;
    Context ctx; //modified
    double lat,lon;
    boolean isGpsEnabled,isNetworkAvailable,isLocationSet;
    LocationManager lmgr;
    long minTime = 60*1000*1;
    long minDistance = 10;
    Location loc;

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

        ctx=getActivity(); //added

        View rootView = inflater.inflate(R.layout.nearbyplaces, container, false);
         l=getLocation();
        if(l==null){Toast.makeText(getActivity(), "null", Toast.LENGTH_LONG).show();}
        SupportMapFragment mapFragment = (SupportMapFragment) getChildFragmentManager()
                    .findFragmentById(R.id.map);
            mapFragment.getMapAsync(this);

        return rootView;

    }

您还应该确保不尝试使用空位置放置标记：

代码语言：javascript
复制
@Override
public void onMapReady(GoogleMap map) {
    // TODO Auto-generated method stub

        map.getUiSettings().setAllGesturesEnabled(true);
        map.setMapType(GoogleMap.MAP_TYPE_HYBRID);
        map.setMyLocationEnabled(true);

        //added brackets:
        if(loc!=null){
            ll = new LatLng(loc.getLatitude() , loc.getLongitude());
            map.addMarker(new MarkerOptions().position(ll).title("Marker in Sydney"));
        }


}

您还应该使用位置回调来更新loc。

代码语言：javascript
复制
@Override
public void onLocationChanged(Location location) {
    // TODO Auto-generated method stub
    loc = location;
    if(loc!=null){
        ll = new LatLng(loc.getLatitude() , loc.getLongitude());
        map.addMarker(new MarkerOptions().position(ll).title("Marker in Sydney"));
    }


}
票数 0
EN

Stack Overflow用户

发布于 2015-07-06 18:55:29

代码语言：javascript
复制
if(lmgr==null){{Toast.makeText(getActivity(), "null manager", Toast.LENGTH_LONG).show();}

}

你正在做一个空检查，但它所做的只是打开一个烤面包。你还是想打电话给isGpsEnabled=lmgr.isProviderEnabled(LocationManager.GPS_PROVIDER);

票数 0
EN

Stack Overflow用户

发布于 2015-07-06 19:14:55

将以下代码添加到片段中：

代码语言：javascript
复制
@Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        ctx = activity;
    }

这将修复Null指针异常。

关于ApOps问题，请重新提供以下链接：

android.app.AppOpsManager not find in android project

Could not find class 'android.app.AppOpsManager', referenced from method com.google.android.gms.common.GooglePlayServicesUtil.zza

票数 0
EN
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：

https://stackoverflow.com/questions/31253353

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