Android谷歌地图问题。空指针异常。地图在片段活动中为空

我有这个代码.... 想要在实际纬度和经度上放一个标记。首先，我想在地图上显示地图和位置，稍后是小菜一碟，以便将这些变量添加到标记中。给我带来一个错误：“JavaNullPointer异常”...并且在调试时地图为空它。Android谷歌地图问题。空指针异常。地图在片段活动中为空

谷歌类：

package com.testuni; 


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 android.app.Activity; 
import android.app.FragmentTransaction; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.Button; 
import android.widget.Toast; 

import android.app.Activity; 
import android.location.Criteria; 
import android.location.Location; 
import android.location.LocationListener; 
import android.location.LocationManager; 
import android.os.Bundle; 
import android.support.v4.app.FragmentActivity; 
import android.support.v4.app.FragmentManager; 
import android.view.View; 
import android.widget.Button; 
import android.widget.Toast; 

//extends FragmentActivity 

public class google extends FragmentActivity implements LocationListener { 


    Button btnShowLocation; 

    // GPSTracker class 
GPSTracker gps; 
// GoogleMap googleMap; 

LatLng myPosition; 

private SupportMapFragment map; 
private GoogleMap mMapView; 


// add all necessary things 

protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_google); 

     btnShowLocation = (Button) findViewById(R.id.btnShowLocation); 

     // show location button click event 
     btnShowLocation.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View arg0) {   
       // create class object 
       gps = new GPSTracker(google.this); 

       // check if GPS enabled  
       if(gps.canGetLocation()){ 

        double latitude = gps.getLatitude(); 
        double longitude = gps.getLongitude(); 

        // \n is for new line 
        Toast.makeText(getApplicationContext(), "Your Location is - \nLat: " + latitude + "\nLong: " + longitude, Toast.LENGTH_LONG).show();  
       }else{ 
        // can't get location 
        // GPS or Network is not enabled 
        // Ask user to enable GPS/network in settings 
        gps.showSettingsAlert(); 
       } 

      } 
     }); 


// if Google Play Services are available then 

      // Getting reference to the SupportMapFragment of activity_main.xml 
      // SIRVE ... SupportMapFragment fm = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map); 


    /* fm = SupportMapFragment.newInstance(); 
     FragmentTransaction fragmentTransaction = 
       getChildFragmentManager().beginTransaction(); 
     fragmentTransaction.add(R.id.map, fm); 
     fragmentTransaction.commit(); */ 

      // SupportMapFragment fm = (SupportMapFragment) getFragmentManager().findFragmentById(R.id.map); 
     FragmentManager fm = getSupportFragmentManager(); 
     map = (SupportMapFragment) fm.findFragmentById(R.id.map); 
     if (map == null) { 
      map = SupportMapFragment.newInstance(); 
      fm.beginTransaction().replace(R.id.map, map).commit(); 
     } 

     // GoogleMap = mMapFragment.getMap(); 

      // Getting GoogleMap object from the fragment 
     // mMapView = fm.getMap(); 
     mMapView = map.getMap(); 
      // Enabling MyLocation Layer of Google Map 
     mMapView.setMyLocationEnabled(true); 

      // Getting LocationManager object from System Service LOCATION_SERVICE 
      LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE); 

      // Creating a criteria object to retrieve provider 
      Criteria criteria = new Criteria(); 

      // Getting the name of the best provider 
      String provider = locationManager.getBestProvider(criteria, true); 

      // Getting Current Location 
      Location location = locationManager.getLastKnownLocation(provider); 

      if(location!=null){ 
      // Getting latitude of the current location 
      double latitude = location.getLatitude(); 

      // Getting longitude of the current location 
      double longitude = location.getLongitude(); 

      // Creating a LatLng object for the current location 
      LatLng latLng = new LatLng(latitude, longitude); 

      myPosition = new LatLng(latitude, longitude); 

      mMapView.addMarker(new MarkerOptions().position(myPosition).title("Start")); 

      } 

} 

@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 

} 

}

的服务GPS：

package com.testuni; 

import android.app.AlertDialog; 
import android.app.Service; 
import android.content.Context; 
import android.content.DialogInterface; 
import android.content.Intent; 
import android.location.Location; 
import android.location.LocationListener; 
import android.location.LocationManager; 
import android.os.Bundle; 
import android.os.IBinder; 
import android.provider.Settings; 
import android.util.Log; 

public class GPSTracker extends Service implements LocationListener { 

    private final Context mContext; 

    // flag for GPS status 
    boolean isGPSEnabled = false; 

    // flag for network status 
    boolean isNetworkEnabled = false; 

    // flag for GPS status 
    boolean canGetLocation = false; 

    Location location; // location 
    double latitude; // latitude 
    double longitude; // longitude 

    // The minimum distance to change Updates in meters 
    private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; // 10 meters 

    // The minimum time between updates in milliseconds 
    private static final long MIN_TIME_BW_UPDATES = 1000 * 60 * 1; // 1 minute 

    // Declaring a Location Manager 
    protected LocationManager locationManager; 

    public GPSTracker(Context context) { 
     this.mContext = context; 
     getLocation(); 
    } 

    public Location getLocation() { 
     try { 
      locationManager = (LocationManager) mContext 
        .getSystemService(LOCATION_SERVICE); 

      // getting GPS status 
      isGPSEnabled = locationManager 
        .isProviderEnabled(LocationManager.GPS_PROVIDER); 

      // getting network status 
      isNetworkEnabled = locationManager 
        .isProviderEnabled(LocationManager.NETWORK_PROVIDER); 

      if (!isGPSEnabled && !isNetworkEnabled) { 
       // no network provider is enabled 
      } else { 
       this.canGetLocation = true; 
       if (isNetworkEnabled) { 
        locationManager.requestLocationUpdates(
          LocationManager.NETWORK_PROVIDER, 
          MIN_TIME_BW_UPDATES, 
          MIN_DISTANCE_CHANGE_FOR_UPDATES, this); 
        Log.d("Network", "Network"); 
        if (locationManager != null) { 
         location = locationManager 
           .getLastKnownLocation(LocationManager.NETWORK_PROVIDER); 
         if (location != null) { 
          latitude = location.getLatitude(); 
          longitude = location.getLongitude(); 
         } 
        } 
       } 
       // if GPS Enabled get lat/long using GPS Services 
       if (isGPSEnabled) { 
        if (location == null) { 
         locationManager.requestLocationUpdates(
           LocationManager.GPS_PROVIDER, 
           MIN_TIME_BW_UPDATES, 
           MIN_DISTANCE_CHANGE_FOR_UPDATES, this); 
         Log.d("GPS Enabled", "GPS Enabled"); 
         if (locationManager != null) { 
          location = locationManager 
            .getLastKnownLocation(LocationManager.GPS_PROVIDER); 
          if (location != null) { 
           latitude = location.getLatitude(); 
           longitude = location.getLongitude(); 
          } 
         } 
        } 
       } 
      } 

     } catch (Exception e) { 
      e.printStackTrace(); 
     } 

     return location; 
    } 

    /** 
    * Stop using GPS listener 
    * Calling this function will stop using GPS in your app 
    * */ 
    public void stopUsingGPS(){ 
     if(locationManager != null){ 
      locationManager.removeUpdates(GPSTracker.this); 
     }  
    } 

    /** 
    * Function to get latitude 
    * */ 
    public double getLatitude(){ 
     if(location != null){ 
      latitude = location.getLatitude(); 
     } 

     // return latitude 
     return latitude; 
    } 

    /** 
    * Function to get longitude 
    * */ 
    public double getLongitude(){ 
     if(location != null){ 
      longitude = location.getLongitude(); 
     } 

     // return longitude 
     return longitude; 
    } 

    /** 
    * Function to check GPS/wifi enabled 
    * @return boolean 
    * */ 
    public boolean canGetLocation() { 
     return this.canGetLocation; 
    } 

    /** 
    * Function to show settings alert dialog 
    * On pressing Settings button will lauch Settings Options 
    * */ 
    public void showSettingsAlert(){ 
     AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext); 

     // Setting Dialog Title 
     alertDialog.setTitle("GPS is settings"); 

     // Setting Dialog Message 
     alertDialog.setMessage("GPS is not enabled. Do you want to go to settings menu?"); 

     // On pressing Settings button 
     alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() { 
      public void onClick(DialogInterface dialog,int which) { 
       Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS); 
       mContext.startActivity(intent); 
      } 
     }); 

     // on pressing cancel button 
     alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() { 
      public void onClick(DialogInterface dialog, int which) { 
      dialog.cancel(); 
      } 
     }); 

     // Showing Alert Message 
     alertDialog.show(); 
    } 

    @Override 
    public void onLocationChanged(Location location) { 
    } 

    @Override 
    public void onProviderDisabled(String provider) { 
    } 

    @Override 
    public void onProviderEnabled(String provider) { 
    } 

    @Override 
    public void onStatusChanged(String provider, int status, Bundle extras) { 
    } 

    @Override 
    public IBinder onBind(Intent arg0) { 
     return null; 
    } 

}

我activity_google.xml〜

<?xml version="1.0" encoding="utf-8"?> 


<AbsoluteLayout 
    xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    > 
    <RelativeLayout 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" > 


    <fragment 
     android:id="@+id/map" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentTop="true" 
     class="com.google.android.gms.maps.MapFragment" /> 

    <Button 
     android:id="@+id/btnShowLocation" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_alignParentRight="true" 
     android:layout_alignParentTop="true" 
     android:layout_marginRight="17dp" 
     android:layout_marginTop="18dp" 
     android:text="Button" /> 

    </RelativeLayout> 


</AbsoluteLayout>

其实我正尝试修复它....任何帮助将不胜感激...谢谢nn

来源

2014-05-05 Arnoldo Bazaldua

注意：这与您的问题无关，但对于信息，从API 3开始已弃用“AbsoluteLayout”。 – Fllo

好的，谢谢您的评论！我删除它...只剩左da Relativelayout –

对于刚刚发布的人！谢谢！！ –

试图改变这一点：

class="com.google.android.gms.maps.MapFragment"

这一类：

class="com.google.android.gms.maps.SupportMapFragment"

，因为你正在使用SupportMapFragment类检索片段。

来源

2014-05-05 16:09:39 Fllo

Android谷歌地图问题。空指针异常。地图在片段活动中为空

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