Filelist Throws NullPointerException

Question

I have the following code in my app:

String[] filelist = APP.getContext().filelist();  

...

public class APP extends Application {
    static Context theContext;

    public void onCreate() {
        super.onCreate();
        theContext = this;
    }

    public static Context getContext() {
        Log.v("APP", "APP.getContext() called.");
        return theContext;
    }
}

The method Context.filelist() returns a NullPointerException no matter how I rewrite this code. Why would it do that?

I can confirm that the VERBOSE log in getContext() displays.

Logcat:

D/AndroidRuntime(  342): >>>>>> AndroidRuntime START com.android.internal.os.RuntimeInit <<<<<<
D/AndroidRuntime(  342): CheckJNI is ON
D/AndroidRuntime(  342): Calling main entry com.android.commands.am.Am
I/ActivityManager(   83): Starting: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10000000 cmp=com.gobernador/.TopPage } from pid 342
I/ActivityManager(   83): Start proc com.gobernador for activity com.gobernador/.TopPage: pid=350 uid=10036 gids={3002}
D/AndroidRuntime(  342): Shutting down VM
D/dalvikvm(  342): GC_CONCURRENT freed 102K, 69% free 319K/1024K, external 0K/0K, paused 1ms+1ms
D/dalvikvm(  342): Debugger has detached; object registry had 1 entries
I/AndroidRuntime(  342): NOTE: attach of thread 'Binder Thread #3' failed
W/dalvikvm(  350): Exception Ljava/lang/NullPointerException; thrown while initializing Lcom/gobernador/APP;
W/dalvikvm(  350): Class init failed in newInstance call (Lcom/gobernador/APP;)
D/AndroidRuntime(  350): Shutting down VM
W/dalvikvm(  350): threadid=1: thread exiting with uncaught exception (group=0x40015560)
I/ARMAssembler(   83): generated scanline__00000177:03515104_00001002_00000000 [ 87 ipp] (110 ins) at [0x444ea6f0:0x444ea8a8] in 1886492 ns
E/AndroidRuntime(  350): FATAL EXCEPTION: main
E/AndroidRuntime(  350): java.lang.ExceptionInInitializerError
E/AndroidRuntime(  350):    at java.lang.Class.newInstanceImpl(Native Method)
E/AndroidRuntime(  350):    at java.lang.Class.newInstance(Class.java:1409)
E/AndroidRuntime(  350):    at android.app.Instrumentation.newApplication(Instrumentation.java:957)
E/AndroidRuntime(  350):    at android.app.Instrumentation.newApplication(Instrumentation.java:942)
E/AndroidRuntime(  350):    at android.app.LoadedApk.makeApplication(LoadedApk.java:461)
E/AndroidRuntime(  350):    at android.app.ActivityThread.handleBindApplication(ActivityThread.java:3260)
E/AndroidRuntime(  350):    at android.app.ActivityThread.access$2200(ActivityThread.java:117)
E/AndroidRuntime(  350):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:969)
E/AndroidRuntime(  350):    at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime(  350):    at android.os.Looper.loop(Looper.java:123)
E/AndroidRuntime(  350):    at android.app.ActivityThread.main(ActivityThread.java:3683)
E/AndroidRuntime(  350):    at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(  350):    at java.lang.reflect.Method.invoke(Method.java:507)
E/AndroidRuntime(  350):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
E/AndroidRuntime(  350):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
E/AndroidRuntime(  350):    at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime(  350): Caused by: java.lang.NullPointerException
E/AndroidRuntime(  350):    at com.gobernador.ReaderWriter.<init>(ReaderWriter.java:20)
E/AndroidRuntime(  350):    at com.gobernador.APP.<clinit>(APP.java:11)
E/AndroidRuntime(  350):    ... 16 more
W/ActivityManager(   83):   Force finishing activity com.gobernador/.TopPage

PER ACCEPTED ANSWER: The code I had written was out of order. I moved the constructor (which contained the line above) to the line after theContext = this;.

You don't have to initialize the array, a declaration is enough. — Andreas Dolk, Mar 01 '12 at 21:03
APP is very similar to [this](http://stackoverflow.com/questions/987072/using-application-context-everywhere) way of doing things. Should I redesign the way I do this? — gobernador, Mar 01 '12 at 21:23
Not necessarily, but you should certainly show your relevant code... — kabuko, Mar 01 '12 at 21:27

score 0 · Answer 1 · answered Mar 01 '12 at 21:13

0

The "new String [9]" is useless. You can simply write it this way :

final String[] filelist = APP.getContext().filelist();

But it won't resolve your problem. The thing is that either "APP" is null or "APP.getContext()" returns null

answered Mar 01 '12 at 21:13

n1r3

8,593
3
18
19

score 0 · Accepted Answer · answered Mar 04 '12 at 04:27

0

theContext is not initialized until your class is instantiated, so it will be null until then.

Make the getContext() method non-static and call it from an instance of that class

One way is call

((APP)(this.getApplication())).getContext().filelist()

from another Activity in your application.

answered Mar 04 '12 at 04:27

Matthieu

16,103
10
59
86

Accepted because you made me realize that I was calling the constructor containing the line of code in question before I had actually stored any value to `theContext` by way of `APP.onCreate()`. Thank you! – gobernador Mar 04 '12 at 04:35

Filelist Throws NullPointerException

2 Answers2