java - Program crashes when I call CallVoidMethodA -

i try call several non-static java methods c. i've checked if of object, method or env variables null, none of them are. program works when use static methods instead of non-static

javavm *jvm; jobject g_obj; jmethodid g_mid;  void func(){   jclass dtk_anpr_test;   jmethodid dtk_anpr;   dtk_anpr_test = (*env)->findclass(env, "dtkanprtest");   g_mid = (*env)->getmethodid(env, dtk_anpr_test, "anpr", "(i)v");   jobject obj = (*env)->newobjecta(env, dtk_anpr_test, g_mid, val);   g_obj = (*env)->newglobalref(env, dtk_anpr_test);  } 

and call (*env)->callvoidmethoda(env, g_obj, g_mid, val); same method or method, program crashes @ point. problem object or else ?

p.s. use attachcurrentthread , detachcurrentthread call method time native code

p.s. there similar thread, didn't solve problem: jni crashes when calling callvoidmethod

to return constructor function of class getmethodid, pass <init> method name, not class name. the docs:

jobject newobjecta(jnienv *env, jclass clazz, jmethodid methodid, const jvalue *args);

constructs new java object. method id indicates constructor method invoke. id must obtained calling getmethodid() <init> method name , void (v) return type.

so change code to:

g_mid = (*env)->getmethodid(env, dtk_anpr_test, "<init>", "(i)v"); 

also, aren't saving reference object creating newobjecta. change code this:

g_obj = (*env)->newglobalref(env, obj); 

the reason code working static methods class object used rather object instance when calling static method.