Android - 作为 InputStream 的原始资源

Question

So I'm trying to make an HTTPS connection with Android, using a client certificate to validate. I've imported this certificate into a BKS store, and inserted in my res/raw.

All good.

However, when I come to run, I get a constant NullPointerException.
For context, I have a Connection class, extending Application, and the basic constructor should just open the cert as an InputStream and hold it ready. When I come to make the connection, this will be used. As follows (abridged):

public class RCPHandshake2 extends Application {

   InputStream in;

   public RCPHandshake2(){
    super.onCreate();
    in = getResources().openRawResource(R.raw.test);        
   }

}

The build-up to this runs fine, however, when we get to there (line 36 in real version), the stack trace is like so:

java.lang.RuntimeException: Unable to start activity   ComponentInfo{com.<company>.t1v2/com.<company>.t1v2.SplashAndText}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2496)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512)
at android.app.ActivityThread.access$2200(ActivityThread.java:119)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1863)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:123)
at android.app.ActivityThread.main(ActivityThread.java:4363)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:521)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at android.content.ContextWrapper.getResources(ContextWrapper.java:80)
at com.<company>.<component>.RCPHandshake2.<init>(RCPHandshake2.java:36)
at com.<company>.t1v2.SplashAndText.onCreate(SplashAndText.java:43)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2459)
... 11 more

This seems unexpected. Has anyone come across similar before?
Eternal love and appreciation in exchange for any solutions/hints/tips/pointers from someone a bit more experienced with it that me!!

PS - Basically, even though I know the raw resource is there, and it appears in R.java, this seems to think it's unable to access it? Is this the case, or am I missing something blinding?

Answer 1

It seems you can't access resources from constructor, as the object has not been initilized yet. Try to call it later, when you really need this first time.

Answer 2

I had the same problem. Turned out that I used a wrong (empty) Context, so there actually were no resources to access via getResource() -> NullPointerException...

Answer 3

To open these resources with a raw InputStream, call Resources.openRawResource() with the resource ID, which is R.raw.filename.