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Android Build a Weather App (2015) Hooking Up the Model to the View Setting the Weather Icon

Sølvi Qorda
Sølvi Qorda
14,194 Points
Posted by Sølvi Qorda
Sølvi Qorda
14,194 Points

Getting a fatal runtime error for OKHttp, and my log doesn't appear to show any retrieval of Forecast data.

Hi community!

I'm still struggling to retrieve any data, and my app crashes on startup. Any ideas much appreciated!

E/AndroidRuntime: FATAL EXCEPTION: main java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{qorda_projects....}: java.lang.NullPointerException

Gavin Ralston
Gavin Ralston
28,770 Points
Gavin Ralston
Gavin Ralston
28,770 Points

Usually there's a few lines after this that say things like "at (line number)" and maybe even the method which is throwing the error.

That'll help narrow it down a bit. Null pointer exceptions are annoying, but it might help to see what you're trying to point at to see what's missing. Then you can hunt down the culprit (the object that wasn't instantiated, the array index that was out of bounds, etc)

Sølvi Qorda
Sølvi Qorda
14,194 Points
Sølvi Qorda
Sølvi Qorda
14,194 Points

Hi Gavin,

thanks for your answer - so I'm looking for a null pointer exception at the lines listed below? What should I try to change?

Kind regards

 FATAL EXCEPTION: OkHttp Dispatcher
                                                                            Process: qorda_projects.stormzystormz, PID: 3656
                                                                            java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
                                                                                at qorda_projects.stormzystormz.CurrentWeather.<init>(CurrentWeather.java:50)
                                                                                at qorda_projects.stormzystormz.MainActivity.getCurrentDetails(MainActivity.java:179)
                                                                                at qorda_projects.stormzystormz.MainActivity.access$400(MainActivity.java:32)
                                                                                at qorda_projects.stormzystormz.MainActivity$2.onResponse(MainActivity.java:119)
                                                                                at com.squareup.okhttp.Call$AsyncCall.execute(Call.java:168)
                                                                                at com.squareup.okhttp.internal.NamedRunnable.run(NamedRunnable.java:33)
                                                                                at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
                                                                                at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
                                                                                at java.lang.Thread.run(Thread.java:818)

(apologies, it's formatted so that you have to scroll right to see the main body of text)

1 Answer

Gavin Ralston
Gavin Ralston
28,770 Points
Gavin Ralston
Gavin Ralston
28,770 Points

Ok so, remember the stack trace is "upside down" showing from the bottom up a list of methods that called the next one, which called the next one... til it broke down. I edited it down a little so it'd fit.

java.lang.NullPointerException: [Tried to do a string comparison on nothing] 'boolean
java.lang.String.equals(java.lang.Object)' on a null object reference

at qorda_projects.stormzystormz.CurrentWeather.<init>(CurrentWeather.java:50)
at qorda_projects.stormzystormz.MainActivity.getCurrentDetails(MainActivity.java:179)
at qorda_projects.stormzystormz.MainActivity.access$400(MainActivity.java:32)
at qorda_projects.stormzystormz.MainActivity$2.onResponse(MainActivity.java:119)

So where I'd start is around line 119 in MainActivity (which looks like it's in the onResponse() callback) then follow along and watch what's happening.

You wind up calling getCurrentDetails() and then you create a new CurrentWeather object, and then somewhere you're messing around with a string that doesn't exist. (That's where I put my "summary" of the error message in brackets in the stack trace above)

You can post the code if you want from MainActivity if you want extra eyes on it, but I think the problem probably exists in the CurrentWeather class.

If I were a betting man, I'd look into the "if/else" statements for the getIconId() method, where the tutorial had you doing a lot of checking out the icon type strings (like clear-day, or cloudy-night) in order to properly set the iconID from your project resources.

If you want to confirm that, try setting a debug point right at the spot where you call .setIcon() on the CurrentWeather object inside your getCurrentDetails() method and then step through and watch the variables change... or watch your code break, and try to figure out what the culprit is. Or if you want to check it a little closer, set the debug point one line into the CurrentWeather.getIconId() method and watch as it checks each icon name value.