我在Android中制作了一个简单的基于GPS /谷歌地图的应用程序，当它刚刚抛出这个可怕的错误时我就完成了它。我真的不知道从哪里开始尝试调试这个，因为它并没有停止在我放在主要活动的任何断点，我不熟悉android，java或eclipse。 所以很烦人，因为我只是要将整个主文件转储到这里
基本上，应用程序的重点是它会找到你的位置，然后你可以选择根据你的位置提出维基百科文章
编辑：我已经尝试重新启动模拟器，日食，清理和重建
任何帮助都将受到大力赞赏
logcat的：
05-21 03:41:45.283: E/AndroidRuntime(1846): FATAL EXCEPTION: main
05-21 03:41:45.283: E/AndroidRuntime(1846): Process: com.example.playservicestest, PID: 1846
05-21 03:41:45.283: E/AndroidRuntime(1846): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.playservicestest/com.example.playservicestest.MainActivity}: java.lang.NullPointerException
05-21 03:41:45.283: E/AndroidRuntime(1846): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
05-21 03:41:45.283: E/AndroidRuntime(1846): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
05-21 03:41:45.283: E/AndroidRuntime(1846): at android.app.ActivityThread.access$800(ActivityThread.java:135)
05-21 03:41:45.283: E/AndroidRuntime(1846): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
05-21 03:41:45.283: E/AndroidRuntime(1846): at android.os.Handler.dispatchMessage(Handler.java:102)
05-21 03:41:45.283: E/AndroidRuntime(1846): at android.os.Looper.loop(Looper.java:136)
05-21 03:41:45.283: E/AndroidRuntime(1846): at android.app.ActivityThread.main(ActivityThread.java:5017)
05-21 03:41:45.283: E/AndroidRuntime(1846): at java.lang.reflect.Method.invokeNative(Native Method)
05-21 03:41:45.283: E/AndroidRuntime(1846): at java.lang.reflect.Method.invoke(Method.java:515)
05-21 03:41:45.283: E/AndroidRuntime(1846): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
05-21 03:41:45.283: E/AndroidRuntime(1846): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
05-21 03:41:45.283: E/AndroidRuntime(1846): at dalvik.system.NativeStart.main(Native Method)
05-21 03:41:45.283: E/AndroidRuntime(1846): Caused by: java.lang.NullPointerException
05-21 03:41:45.283: E/AndroidRuntime(1846): at com.example.playservicestest.MainActivity.onCreate(MainActivity.java:101)
05-21 03:41:45.283: E/AndroidRuntime(1846): at android.app.Activity.performCreate(Activity.java:5231)
05-21 03:41:45.283: E/AndroidRuntime(1846): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
05-21 03:41:45.283: E/AndroidRuntime(1846): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
05-21 03:41:45.283: E/AndroidRuntime(1846): ... 11 more
源：
package com.example.playservicestest;
import java.io.IOException;
import java.util.List;
import java.util.Locale;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.MapFragment;
import com.google.android.gms.maps.model.CameraPosition;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;
import com.google.android.maps.GeoPoint;
import com.google.android.maps.MapController;
import com.google.android.maps.MapView;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.location.Address;
import android.location.Criteria;
import android.location.Geocoder;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends Activity {
//Map globals
LocationManager mLocationManager ;
Criteria mCriteria = new Criteria();
String mBestProvider;
Location mLocation;
GoogleMap mMap;
GeoPoint mMapPosition;
//String globals
String localityString;
String countryString;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Widget assigning
TextView tLocationText = (TextView) findViewById(R.id.Location_text);
//Location Initialising
mLocationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
mBestProvider = mLocationManager.getBestProvider(mCriteria, false);
mLocation = mLocationManager.getLastKnownLocation(mBestProvider);
mCriteria.setAccuracy(Criteria.ACCURACY_COARSE);
mCriteria.setPowerRequirement(Criteria.POWER_LOW);
mCriteria.setAltitudeRequired(false);
mCriteria.setBearingRequired(false);
mCriteria.setSpeedRequired(false);
mCriteria.setCostAllowed(true);
localityString = "Nothing yet!";
countryString = "Nothing yet!";
int iminTime = 2000;
int iminDistance = 50;
LocationListener mLocationListener = new LocationListener()
{
public void onLocationChanged(Location location)
{
// Update application based on new location.
updateLocation(location);
}
public void onProviderDisabled(String provider)
{
// Update application if provider disabled.
updateLocation(null);
}
public void onProviderEnabled(String provider)
{
// Update application if provider enabled.
}
public void onStatusChanged(String provider, int status,Bundle extras)
{
// Update application if provider hardware status changed.
}
};
updateLocation(mLocation);
mLocationManager.requestLocationUpdates(mBestProvider, iminTime, iminDistance, mLocationListener);
mMap = ((MapFragment) getFragmentManager().findFragmentById(R.id.map_fragment)).getMap();
LatLng CurrPos = new LatLng(mLocation.getLatitude(),mLocation.getLongitude());
mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(CurrPos, 13));
Button bCurrentPosition = (Button)findViewById(R.id.Current_pos);
bCurrentPosition.setOnClickListener(CurrentPositionListener);
Button bChangePosition = (Button)findViewById(R.id.Change_pos);
bChangePosition.setOnClickListener(ChangePositionListener);
}
public void callIntent(View view)
{
Intent intent = null;
if(view.getId()==R.id.Find_info)
{
if(localityString!="Somewhere in")
{
intent = new Intent(Intent.ACTION_VIEW,Uri.parse("http://en.wikipedia.org/wiki/"+localityString));
}
else if(countryString!="the middle of the ocean")
{
intent = new Intent(Intent.ACTION_VIEW,Uri.parse("http://en.wikipedia.org/wiki/"+countryString));
}
else
{
intent = new Intent(Intent.ACTION_VIEW,Uri.parse("http://en.wikipedia.org/wiki/Ocean"));
}
}
startActivity(intent);
}
View.OnClickListener CurrentPositionListener = new View.OnClickListener()
{
@Override
public void onClick(View v)
{
findCurrentPosition();
}
};
View.OnClickListener ChangePositionListener = new View.OnClickListener()
{
@Override
public void onClick(View v)
{
setTargetPosition();
}
};
public void updateLocation(Location location)
{
TextView mtextview = (TextView)findViewById(R.id.Location_text);
if(location !=null)
{
mtextview.setText("Lat: "+location.getLatitude()+"\nLong: "+location.getLongitude()+"\n");
}
else
{
mtextview.setText("No Location found");
}
}
public void findCurrentPosition()
{
if(mLocation !=null)
{
LatLng CurrPos = new LatLng(mLocation.getLatitude(),mLocation.getLongitude());
mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(CurrPos, 5.0f));
double lat = mLocation.getLatitude();
double lng = mLocation.getLongitude();
LatLng Point = new LatLng(lat,lng);
setAddressMarker(Point);
}
}
public void setTargetPosition()
{
TextView tLocationText = (TextView) findViewById(R.id.Location_text);
CameraPosition TargetPosition = mMap.getCameraPosition();
double lat = TargetPosition.target.latitude;
double lng = TargetPosition.target.longitude;
LatLng Point = new LatLng(lat,lng);
setAddressMarker(Point);
}
void setAddressMarker(LatLng Point)
{
TextView tLocationText = (TextView) findViewById(R.id.Location_text);
Geocoder gc = new Geocoder(this);
try{
List<Address> addresses = gc.getFromLocation(Point.latitude, Point.longitude, 1);
//targetAddress.getLocale()
if(addresses.size()>0)
{
Address targetAddress = addresses.get(0);
if(targetAddress.getLocality()!=null)
{
localityString = targetAddress.getLocality();
}
else
{
localityString = "Somewhere in";
}
if(targetAddress.getCountryName()!=null)
{
countryString = targetAddress.getCountryName();
}
else
{
countryString = "the middle of the ocean";
}
}
else
{
localityString = "Somewhere in";
countryString = "the middle of the ocean";
}
}
catch (IOException e)
{
e.printStackTrace();
}
tLocationText.setText("You're target is: "+ localityString +" "+ countryString);
mMap.addMarker(new MarkerOptions()
.title(localityString)
.snippet(countryString)
.position(Point));
}
}
清单文件：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.playservicestest"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="11"
android:targetSdkVersion="18" />
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.CHANGE_NETWORK_STATE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES"/>
<!-- The following two permissions are not required to use
Google Maps Android API v2, but are recommended. -->
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-feature
android:glEsVersion="0x00020000"
android:required="true"/>
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<meta-data android:name="com.google.android.gms.version"
android:value="@integer/google_play_services_version" />
<meta-data
android:name="com.google.android.maps.v2.API_KEY"
android:value="AIzaSyA4XfZDxD_pzC4wyF4nsQPjvMZIl3V-Mew"/>
<activity
android:name="com.example.playservicestest.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
答案 0 :(得分：1)
所以问题是位置，从互联网查看一些如何使用它的例子。像这样https://thenewcircle.com/s/post/311/tutorial_android_location_service_example