Android native code crash

I have a test case where java is calling a simple routine in C with a couple of args and it returns a string and it works.

However, when I coded up my real code the same way it crashes with an "Invocation Target Exception". I then simplified it to just a call and return of a string and it still crashes.

One difference between the two cases is that one of the calls has 6 floating-point args, and the other one has 14 floating ars. The 6-arg one gets called first (a setup) and I get the exception.

Is there any practical limitation on number of args that can be in a call to native code? Or should I continue looking at my code for the problem elsewhere?

Sorry - I couldn't get the logcat to format as a comment so I'm posting it as an edit instead. Here's the logcat, any suggestion where I should look? What does "No implementation found" mean?

D/dalvikvm(  531): Added shared lib /data/data/com.kinyur.etold/lib/libgalib.so 0x405133e0
D/dalvikvm(  531): No JNI_OnLoad found in /data/data/com.kinyur.etold/lib/libgalib.so 0x405133e0, skipping init
W/dalvikvm(  531): No implementation found for native Lcom/kinyur/etold/NativeLib;.setup (FFFFFF)Ljava/lang/String;
D/AndroidRuntime(  531): Shutting down VM
W/dalvikvm(  531): threadid=1: thread exiting with uncaught exception (group=0x40015560)
E/Androi开发者_C百科dRuntime(  531): FATAL EXCEPTION: main

The routine is called with 6 floats and returns a String type. And the "setup" is the name of the routine I called when it crashed.

I'm not aware of any limitations of the number of arguments of a JNI method

Sorry for the distraction, I spent all day on this and found that the problem was just a stupid typo on my part, probably a copy-and-paste problem.

Interesting also that I had protected the native call with a try...catch block, but the program still crashed instead of getting an exception.

I had two problems. The first primary one was:

The decorated name of the routine in my .C file was wrong. In my test case that worked, I was using:

JNIEXPORT jstring JNICALL Java_com_example_atest_NativeLib_hello

and in my real case I wanted:

JNIEXPORT jstring JNICALL Java_com_kinyur_etold_NativeLib_doSetup

but what I had was:

JNIEXPORT jstring JNICALL Java_com_example_atest_NativeLib_doSetup

so I had cruft left over from when I copied the case that worked into the new one. I don't know how many times I looked at it today and didn't notice it. :-(

And interestingly enough, according to logcat, it seemed to link to the library OK and failed when it ran (using the routine name 'hello' instead of 'doSetup'):

D/dalvikvm(  460): Trying to load lib /data/data/com.kinyur.etold/lib/libgalib.so 0x40515840
D/dalvikvm(  460): Added shared lib /data/data/com.kinyur.etold/lib/libgalib.so0x40515840
D/dalvikvm(  460): No JNI_OnLoad found in /data/data/com.kinyur.etold/lib/libgalib.so 0x40515840, skipping init
W/dalvikvm(  460): No implementation found for native Lcom/kinyur/etold/NativeLib;.hello ()Ljava/lang/String;
D/AndroidRuntime(  460): Shutting down VM
W/dalvikvm(  460): threadid=1: thread exiting with uncaught exception (group=0x40015560)
E/AndroidRuntime(  460): FATAL EXCEPTION: main
E/AndroidRuntime(  460): java.lang.UnsatisfiedLinkError: hello
E/AndroidRuntime(  460):        at com.kinyur.etold.NativeLib.hello(Native Method)
E/AndroidRuntime(  460):        at com.kinyur.etold.ComFields.<init>(ComFields.java:33)
E/AndroidRuntime(  460):        at com.kinyur.etold.EtMain.onCreate(EtMain.java:28)
E/AndroidRuntime(  460):        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)

The SECOND problem I found while hunting for the first one was that I was incorrectly returning a string in the C routine.

I had:

char* aString = "1234";
return aString;

What was needed was:

return (*env)->NewStringUTF(env, aString);