i am getting exceptiion like below

LocationManager lm = (LocationManager)getSystemService(Context.LOCATION_SERVICE); 
                    Location location = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
                     double longitude = location.getLongitude(开发者_如何学JAVA);
                     double latitude = location.getLatitude();


                if(location == null){
                   longitude = 0.0;
                   latitude = 0.0;
                   Log.i("CURRENT LONGITUDE", ""+longitude);
                   Log.i("CURRENT LATITUDE", ""+latitude);
                }

                Log.i("CURRENT LONGITUDE", ""+longitude);
                Log.i("CURRENT LATITUDE", ""+latitude); 

I am getting problem at line "double longitude = location.getLongitude();" which is line 93 in MainActivity;

03-18 16:52:26.928: ERROR/AndroidRuntime(9598): java.lang.NullPointerException
03-18 16:52:26.928: ERROR/AndroidRuntime(9598):     at com.demo.parsing.MainActivity$1.onClick(MainActivity.java:93)
03-18 16:52:26.928: ERROR/AndroidRuntime(9598):     at android.view.View.performClick(View.java:2364)
03-18 16:52:26.928: ERROR/AndroidRuntime(9598):     at android.view.View.onTouchEvent(View.java:4179)
03-18 16:52:26.928: ERROR/AndroidRuntime(9598):     at android.widget.TextView.onTouchEvent(TextView.java:6540)
03-18 16:52:26.928: ERROR/AndroidRuntime(9598):     at android.view.View.dispatchTouchEvent(View.java:3709)
03-18 16:52:26.928: ERROR/AndroidRuntime(9598):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
03-18 16:52:26.928: ERROR/AndroidRuntime(9598):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
03-18 16:52:26.928: ERROR/AndroidRuntime(9598):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
03-18 16:52:26.928: ERROR/AndroidRuntime(9598):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
03-18 16:52:26.928: ERROR/AndroidRuntime(9598):     at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1659)
03-18 16:52:26.928: ERROR/AndroidRuntime(9598):     at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1107)
03-18 16:52:26.928: ERROR/AndroidRuntime(9598):     at android.app.Activity.dispatchTouchEvent(Activity.java:2061)
03-18 16:52:26.928: ERROR/AndroidRuntime(9598):     at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1643)
03-18 16:52:26.928: ERROR/AndroidRuntime(9598):     at android.view.ViewRoot.handleMessage(ViewRoot.java:1691)
03-18 16:52:26.928: ERROR/AndroidRuntime(9598):     at android.os.Handler.dispatchMessage(Handler.java:99)
03-18 16:52:26.928: ERROR/AndroidRuntime(9598):     at android.os.Looper.loop(Looper.java:123)
03-18 16:52:26.928: ERROR/AndroidRuntime(9598):     at android.app.ActivityThread.main(ActivityThread.java:4363)
03-18 16:52:26.928: ERROR/AndroidRuntime(9598):     at java.lang.reflect.Method.invokeNative(Native Method)
03-18 16:52:26.928: ERROR/AndroidRuntime(9598):     at java.lang.reflect.Method.invoke(Method.java:521)
03-18 16:52:26.928: ERROR/AndroidRuntime(9598):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
03-18 16:52:26.928: ERROR/AndroidRuntime(9598):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
03-18 16:52:26.928: ERROR/AndroidRuntime(9598):     at dalvik.system.NativeStart.main(Native Method)

This is strange:

  double longitude = location.getLongitude();
  double latitude = location.getLatitude();
  if(location == null){

It seems you expect that location can be NULL. But the two lines above that use location to call a member function. If it is NULL, then you will get a nullpointerexception.

in response to your comment: You could easily fix it by changing the order of things:

Location location = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER)
double latitude;
double longitude;
if(location == null){
    longitude = 0.0;
    latitude = 0.0;
    Log.i("CURRENT LONGITUDE", ""+longitude);
    Log.i("CURRENT LATITUDE", ""+latitude);
}else{
    longitude = location.getLongitude();
    latitude = location.getLatitude();
}

Edit 2 If you would just take a quick look at the manual: http://developer.android.com/reference/android/location/LocationManager.html

you would have read this: (emph mine)

Returns a Location indicating the data from the last known location fix obtained from the given provider. This can be done without starting the provider. Note that this location could be out-of-date, for example if the device was turned off and moved to another location. If the provider is currently disabled, null is returned.

You check if location is null only after you used it. It might be null during assignment to longtitude /latitude.