How to read crash reports from Developer Console

Question

I'm trying to track down the source of a bug, based on a crash report submitted by a user, and have come to the conclusion that I need some basic training on how to interpret a crash report.

As an example, the crash report is as follows:

java.lang.NumberFormatException: Invalid int: ""
    at java.lang.Integer.invalidInt(Integer.java:138)
    at java.lang.Integer.parseInt(Integer.java:358)
    at java.lang.Integer.parseInt(Integer.java:334)
    at java.lang.Integer.valueOf(Integer.java:525)
    at com.cloud3squared.meteogram.MeteogramService.cacheFileName(MeteogramService.java)
                                                    cacheBaseName(MeteogramService.java)
                                                    getAppWidgetId(MeteogramService.java)
                                                    createAdhocWidgetUpdateIntent(MeteogramService.java)
                                                    setupBasicClickStuff(MeteogramService.java)
                                                    setAdhocAppWidgetAlarm(MeteogramService.java)
                                                    setNextClockWidgetUpdateAlarm(MeteogramService.java)
                                                    cancelAppWidgetAlarm(MeteogramService.java)
                                                    cancelAppWidgetAlarms(MeteogramService.java)
                                                    logAction$3aaf2084(MeteogramService.java)
                                                    logActionAgainstAllWidgets$62dc3a79(MeteogramService.java)
                                                    updateAppWidget(MeteogramService.java)
                                                    showButtons(MeteogramService.java)
                                                    hideButtons(MeteogramService.java)
                                                    fetchOk(MeteogramService.java)
                                                    getViewId(MeteogramService.java)
                                                    putBitmapIntoWidget(MeteogramService.java)
                                                    lngNow(MeteogramService.java)
                                                    showNotification(MeteogramService.java)
                                                    showMessageInWidget(MeteogramService.java)
                                                    sharpen(MeteogramService.java)
                                                    removeFromRequestsList(MeteogramService.java)
                                                    removeFromRequestsList$204347ff(MeteogramService.java)
                                                                           MeteogramService.java)
                                                    displayStuffInWidget(MeteogramService.java)
                                                    access$000(MeteogramService.java)
                                                    access$100(MeteogramService.java)
                                                    access$300(MeteogramService.java)
    at com.cloud3squared.meteogram.MeteogramService$GetServerWidgetAsyncTask.onPostExecute(MeteogramService.java)
    at android.os.AsyncTask.finish(AsyncTask.java:651)
    at android.os.AsyncTask.access$500(AsyncTask.java:180)
    at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:668)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:224)
    at android.app.ActivityThread.main(ActivityThread.java:5526)
    at java.lang.reflect.Method.invoke(Method.java)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

Is this showing the order of calls leading up to the NumberFormatException, and if so, in what order? Do I read the at lines from bottom to top? What is access nested inside MeteogramService?... there is no access method in that class. How do I determine inside which function the NumberFormatException actually occurs? Logically I would say inside cacheFileName but there is nothing in there that might lead to such an exception... the parsing of a String to an int happens before that... the parsed int is simply passed into cacheFileName.

Any help gratefully received.

EDIT

Further code snippets to refer to in comments below:

static String cacheFileName(Context context, int appWidgetId, int pxWidth, int pxHeight) {
    String fileName = cacheBaseName(appWidgetId) + "_" + pxWidth + "x" + pxHeight + ".png";
    logAction(context, appWidgetId, "cacheFileName " + fileName, TAG);
    return fileName;
}

static String cacheBaseName(int appWidgetId) {
    return (appWidgetId == AppWidgetManager.INVALID_APPWIDGET_ID) ? "widget_" : "widget_" + appWidgetId;
}

Answer 1

You have to read it BOTH from top to bottom and bottom to top.

It's typically more specific from the top to broader at the bottom.

From the TOP: you will find the precise cause of exception

Which in this case is java.lang.NumberFormatException which blows up at cacheFileName's cacheBaseName

From the BOTTOM: you will find the general area of the problem

GetServerWidgetAsyncTask.onPostExecute

What this looks like to me is that it could be some value finished in the background work in the AsyncTask is improperly formatted and used as an int in onPostExecute.

Where I would start off is to debug the values of: pxWidth, pxHeight, and appWidgetId in String fileName = cacheBaseName(appWidgetId) + "_" + pxWidth + "x" + pxHeight + ".png";

Integer.valueOf means it was probably trying to parse a string into an int, example: String "13" into int 13.

Out of those 3 variables, the most probable relation is the appWidgetId since there is another tip about getAppWidgetId. But to be sure, log all 3! =)

Answer 2

The error is in MeteogramService.java file.

The error NumberFormatException is due to an invalid int value, which is possibly because of passing a string or invalid variable into an int.

The list of class names or method names is the order from top to bottom in which the variable has been accessed. Verify if you are passing an int, and in case if it is user defined value, then use a try/catch block and show toast whenever they enter a non-int value.