Question

Been going crazy with ANDROID’s regex using the pattern / matcher methods. I’ve been pretty unsuccessful for several days now. And yes I have been searching SO for help prior to asking for direct help. Ok, here’s the deal: my incoming stream looks like this

Time in UTC (HhMmSs): 154653
Status (A=OK,V=KO): V
Latitude: 4428.2011
Direction (N/S): N

Longitude: 00440.5161

Direction (E/W): W

Speed in knots: 000.5

Direction in degrees: 342.8

Date in UTC (DdMmAa): 050407

Magnetic variation:

Variation (E/W):

Mode: A

All I want for now is the Latitude and Longitude values.

My code looks like this:

public class NmeaParser {
/**
 * Tag used for log messages
 */
public String nmeaData;
public String lat; //latitude
public String lon; //longitude

private static final String LOG_TAG = "NPGPS";



public String longitude, latitude;
//find the text pattern
public static final Pattern NMEA_PATTERN = Pattern.
            compile(
                    "\\d{6}" +
                    ":\\s\\D" +
                    "\\w+\\S\\s\\d{4}.\\d+" +
                    ":\\s\\D" +
                    "\\w+\\S\\s\\d{5}.\\d+" +
                    ":\\s\\D" +
                    "\\d{3}.\\d{1}" +
                    "\\d{3}.\\d{1}" +
                    "\\d{6}" +
                    ":\\s\\D" +
                    ":\\s\\D"
                    //".*" //this works as a test
                    );

public String parseNmeaSentence(String gpsSentence) {
        Matcher rmcMatcher = NMEA_PATTERN.matcher(gpsSentence);
        //Log.i(LOG_TAG, "dataNP: "+ rmcMatcher);
        if (rmcMatcher.find()) {
                //Log.d("Matcher", "PATTERN MATCHES!");
            //else
                //Log.d("MATCHER", "PATTERN DOES NOT MATCH!");
            //String time = rmcMatcher.group(1);
          latitude = rmcMatcher.group(3);
          nmeaData = latitude;

        }
            return nmeaData;
  }
}

and I keep getting these errors:

09-17 11:37:36.936: E/AndroidRuntime(8756): FATAL EXCEPTION: main
09-17 11:37:36.936: E/AndroidRuntime(8756): java.lang.NullPointerException
09-17 11:37:36.936: E/AndroidRuntime(8756):     at                 android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:394)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.widget.ArrayAdapter.getView(ArrayAdapter.java:362)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.widget.AbsListView.obtainView(AbsListView.java:2058)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.widget.ListView.measureHeightOfChildren(ListView.java:1244)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.widget.ListView.onMeasure(ListView.java:1155)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.view.View.measure(View.java:12723)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4698)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1369)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.widget.LinearLayout.measureVertical(LinearLayout.java:660)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.widget.LinearLayout.onMeasure(LinearLayout.java:553)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.view.View.measure(View.java:12723)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4698)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:293)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.view.View.measure(View.java:12723)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.widget.LinearLayout.measureVertical(LinearLayout.java:812)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.widget.LinearLayout.onMeasure(LinearLayout.java:553)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.view.View.measure(View.java:12723)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4698)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:293)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2092)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.view.View.measure(View.java:12723)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1064)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2442)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.os.Handler.dispatchMessage(Handler.java:99)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.os.Looper.loop(Looper.java:137)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at android.app.ActivityThread.main(ActivityThread.java:4575)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at java.lang.reflect.Method.invokeNative(Native Method)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at java.lang.reflect.Method.invoke(Method.java:511)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
09-17 11:37:36.936: E/AndroidRuntime(8756):     at dalvik.system.NativeStart.main(Native Method)

Clearly I’m screwing up with my regex syntax within the pattern / matcher methods.
Any help is clearly appreciated.
thanks!

Answer 1

From your trace it appears that android.widget.ArrayAdapter is missing a resource in your code so this is the real issue why you can’t proceed.

Re your regex, you don’t have any capturing groups in your regular expression and your pattern doesn’t match your input string.

The best approach when using many expressions is to match up 1 or 2 expressions at a time to get those working first.

As you only wanted latitude & longitude, here is that regex code to get you (re-)started:

Pattern NMEA_PATTERN = Pattern.compile(
                ".*Latitude: (\\d{4}.\\d+).*" + 
                "Longitude: (\\d{5}.\\d+).*");
Matcher m = NMEA_PATTERN.matcher(gpsSentence);

if (m.matches()) {
    String latitude = m.group(1);
    String longitude = m.group(2);
    ...
}