正在开发GPS跟踪应用程序。当我按下登录按钮时，它必须显示纬度经度和准确度。它无法正常工作，应用程序崩溃。请帮我解决这个问题。提前谢谢。
这是我的activity.class：
btnShowLocation = (Button) findViewById(R.id.btnShowLocation);
// show location button click event
btnShowLocation.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
AndroidGPSTrackingActivity.this.startService(new Intent(AndroidGPSTrackingActivity.this, GPSTracker.class));
// create class object
// MyTimerTask myTask = new MyTimerTask();
Context c = getApplicationContext();
SharedPreferences app_preferences = PreferenceManager.getDefaultSharedPreferences(c);
@SuppressWarnings("unused")
SharedPreferences.Editor editor = app_preferences.edit();
TimerTask scanTask;
final Handler handler = new Handler();
Timer t = new Timer();
scanTask = new TimerTask() {
GPSTracker gps;
List<Double> l = new ArrayList<Double>();
TreeMap<Double,List<Double>> list = new TreeMap<Double,List<Double>>();
public void run() {
handler.post(new Runnable() {
// @SuppressLint("UseValueOf")
@SuppressLint("UseValueOf")
public void run() {
Context c = getApplicationContext();
SharedPreferences app_preferences = PreferenceManager.getDefaultSharedPreferences(c);
SharedPreferences.Editor editor = app_preferences.edit();
int counter = app_preferences.getInt("counter", 0);
Log.i("log", "maaaap"+list);
Double latitude=new Double(0.0d);
Double longitude=new Double(0.0d);
l = new ArrayList<Double>();
gps = new GPSTracker(AndroidGPSTrackingActivity.this);
// check if GPS enabled
if(gps.canGetLocation()){
l.add(gps.getLatitude());
l.add(gps.getLongitude());
list.put(gps.getAccur(),l);
Toast.makeText(getApplicationContext(), "Your Location is - \nLat: " + gps.getLatitude() + "\nLong:" + gps.getLongitude()+ "\nAccracy:"+gps.getAccur(), Toast.LENGTH_SHORT).show();
Log.i("log", "latitude"+gps.getLatitude());
Log.i("log", "longitude"+gps.getLongitude());
Log.i("log", "gps.getAccur()"+gps.getAccur());
Log.d("tag", "Finding Latitude");
latitude = gps.getLatitude();
Log.d("tag", "Lat: "+String.valueOf(latitude));
Log.d("tag", "Finding Longitude");
longitude = gps.getLongitude();
Log.d("tag", "Lon: "+String.valueOf(longitude));
String Text =
"\nLat: " + gps.getLatitude() +
"\nLan:" + gps.getLongitude()+"\nAcrcy="+gps.getAccur();
//txtData.setText(Text);
sendSMS(readfromFilesms(), Text);
}
if(counter<12)
{
if(gps.getAccur()<=3.0D)
{
Double d = (Double)list.firstKey();
Log.i("log", "gps.firstKey()"+d);
@SuppressWarnings("rawtypes")
List l1 = (List)list.get(d);
Log.i("log", "gps.l1()"+(Double)l1.get(0));
Log.i("log", "gps.l2"+(Double)l1.get(1));
latitude = (Double)l1.get(0);
longitude = (Double)l1.get(1);
// String[] s = {"manjugowda.manju2@gmail.com"};
//SendMail(s,latitude.toString(),longitude.toString(),"22");
editor.putInt("counter", 0);
editor.commit(); // Very important
finish();
//Toast.makeText(getApplicationContext(), "Your Location is - \nLong: "+d , Toast.LENGTH_LONG).show();
}
else
{
counter = app_preferences.getInt("counter", 0);
Log.i("log", "counter"+counter);
editor.putInt("counter", ++counter);
editor.commit();
finish();// Very important
}
}
else
{
Double d = (Double)list.firstKey();
Log.i("log", "gps.firstKey()"+d);
@SuppressWarnings("rawtypes")
List l1 = (List)list.get(d);
Log.i("log", "gps.l1()"+(Double)l1.get(0));
Log.i("log", "gps.l2"+(Double)l1.get(1));
latitude = (Double)l1.get(0);
longitude = (Double)l1.get(1);
//@SuppressWarnings("unused")
//String[] s = {"manjugowda.manju2@gmail.com"};
// SendMail(s,latitude.toString(),longitude.toString(),"22");
editor.putInt("counter", 0);
editor.commit(); // Very important
finish();
//Toast.makeText(getApplicationContext(), "Your Accurecy is - \n: "+d , Toast.LENGTH_LONG).show();
}
}
});
}};
t.schedule(scanTask,1000,90000000);
finish();
}
});
logcat错误：
04-08 18:27:01.438: E/ActivityThread(23915): at java.lang.reflect.Method.invoke(Method.java:515)
04-08 18:27:01.438: E/ActivityThread(23915): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
04-08 18:27:01.438: E/ActivityThread(23915): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
04-08 18:27:01.438: E/ActivityThread(23915): at dalvik.system.NativeStart.main(Native Method)
04-08 18:27:01.904: I/log(23915): maaaap{}
04-08 18:27:01.925: D/GPS Enabled(23915): GPS Enabled
04-08 18:27:01.925: I/System.out(23915): inside location manager
04-08 18:27:01.929: D/AndroidRuntime(23915): Shutting down VM
04-08 18:27:01.929: W/dalvikvm(23915): threadid=1: thread exiting with uncaught exception (group=0x416c8d40)
04-08 18:27:01.948: E/AndroidRuntime(23915): FATAL EXCEPTION: main
04-08 18:27:01.948: E/AndroidRuntime(23915): Process: com.example.gpstracking, PID: 23915
04-08 18:27:01.948: E/AndroidRuntime(23915): java.lang.NullPointerException
04-08 18:27:01.948: E/AndroidRuntime(23915): at com.example.gpstracking.AndroidGPSTrackingActivity$1$1$1.run(AndroidGPSTrackingActivity.java:163)
04-08 18:27:01.948: E/AndroidRuntime(23915): at android.os.Handler.handleCallback(Handler.java:733)
04-08 18:27:01.948: E/AndroidRuntime(23915): at android.os.Handler.dispatchMessage(Handler.java:95)
04-08 18:27:01.948: E/AndroidRuntime(23915): at android.os.Looper.loop(Looper.java:136)
04-08 18:27:01.948: E/AndroidRuntime(23915): at android.app.ActivityThread.main(ActivityThread.java:5102)
04-08 18:27:01.948: E/AndroidRuntime(23915): at java.lang.reflect.Method.invokeNative(Native Method)
04-08 18:27:01.948: E/AndroidRuntime(23915): at java.lang.reflect.Method.invoke(Method.java:515)
04-08 18:27:01.948: E/AndroidRuntime(23915): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
04-08 18:27:01.948: E/AndroidRuntime(23915): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
04-08 18:27:01.948: E/AndroidRuntime(23915): at dalvik.system.NativeStart.main(Native Method)
04-08 18:27:03.605: I/Process(23915): Sending signal. PID: 23915 SIG: 9
GPSTracker.class：
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
Double accur;
public Double getAccur() {
return accur;
}
public void setAccur(Double accur) {
this.accur = accur;
}
// The minimum distance to change Updates in meters
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 12; // 10 meters
// The minimum time between updates in milliseconds
private static final long MIN_TIME_BW_UPDATES = 0; // 1 sec
// Declaring a Location Manager
protected LocationManager locationManager;
public Object getAccuracy;
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){
System.out.println("inside location");
latitude = location.getLatitude();
System.out.println("lat"+latitude);
longitude = location.getLongitude();
}
}
}*/
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) {
System.out.println("inside location manager");
location = locationManager
.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (location != null) {
System.out.println("inside location");
latitude = location.getLatitude();
System.out.println("lat"+latitude);
longitude = location.getLongitude();
}
}
}
}
if(location!=null)
{
setAccur(new Double(location.getAccuracy()));
}
} 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;
}
}
答案 0 :(得分：1)
根据您的代码。我找到了崩溃的问题。可能是你的gps的实例是null或者被改为null。先检查一下
if(gps!=null){
//your code
}else{
Log.i("Your Classs Name::","GPS Object is null")
}
我确定你会收到日志消息，因为GPS对象为空..
如果仍然获得Null，则重新初始化gps对象。