Hi,
I am porting one multi-threaded native code to android platform,
created shared library,
I am using some of the Android java applications by using JNI, when i
call Java code from C, i am getting NoClassDefFoundError Exception on
runtime,
E/MY-ALSA ( 3508): JNI_OnLoad called
E/MY-ALSA ( 3508): initClassHelper: failed to get class reference
W/dalvikvm( 3508): Exception Ljava/lang/NoClassDefFoundError; thrown
while initializing Lcom/example/hellojni/HelloJni;
W/dalvikvm( 3508): Class init failed in newInstance call (Lcom/example/
hellojni/HelloJni;)
D/AndroidRuntime( 3508): Shutting down VM
W/dalvikvm( 3508): threadid=1: thread exiting with uncaught exception
(group=0xb586a4f0)
Below is the Java and native code, and please help me to resolve it, i
am new to java.
/* ---------------------------------------------------- Java code
--------------------------------------------------------------------
*/
public class HelloJni extends Activity
{
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
/* Create a TextView and set its content.
* the text is retrieved by calling a native
* function.
*/
TextView tv = new TextView(this);
tv.setText( stringFromJNI() );
setContentView(tv);
}
public boolean javaFunc(String s)
{
/* Do some application work */
return true;
}
/* A native method that is implemented by the
* 'hello-jni' native library, which is packaged
* with this application.
*/
public native String stringFromJNI();
static {
System.loadLibrary("hello-jni");
}
}
/* ---------------------------------------------------- Jni code
--------------------------------------------------------------------
*/
/* Global data */
JavaVM* javaVM;
jobject obj;
jstring
Java_com_example_hellojni_HelloJni_stringFromJNI( JNIEnv* env_var,
jobject thiz)
{
/* here i am initializing few native threads */
return (*env)->NewStringUTF(env, "Hello from JNI!");
}
oneThreadFun()
{
int status;
JNIEnv *env;
bool isAttached = false;
status = (*javaVM)->GetEnv(javaVM, (void **) &env,
JNI_VERSION_1_4);
if(status < 0) {
__android_log_print(ANDROID_LOG_ERROR, "NativeCode",
"callback_handler: failed to get JNI environment, "
"assuming native thread");
status = (*javaVM)->AttachCurrentThread(javaVM, &env, NULL);
if(status < 0) {
__android_log_print(ANDROID_LOG_ERROR, "NativeCode",
"callback_handler: failed to attach "
"current thread");
return;
}
isAttached = true;
}
/* Construct a Java string */
//jstring js = env->NewStringUTF(s);
jclass interfaceClass = (*env)->GetObjectClass(env, obj);
if(!interfaceClass) {
__android_log_print(ANDROID_LOG_ERROR, "NativeCode",
"callback_handler: failed to get class reference");
if(isAttached) (*javaVM)->DetachCurrentThread(javaVM);
return;
}
/* Find the callBack method ID */
jmethodID method = (*env)->GetStaticMethodID(env, interfaceClass,
"javaFunc", "(Ljava/lang/String;)V");
if(!method) {
__android_log_print(ANDROID_LOG_ERROR, "NativeCode",
"callback_handler: failed to get method ID");
if(isAttached) (*javaVM)->DetachCurrentThread(javaVM);
return;
}
jstring js;
(*env)->CallStaticVoidMethod(env, interfaceClass, method, js);
if(isAttached) (*javaVM)->DetachCurrentThread(javaVM);
return;
}
static jobject io;
jint JNI_OnLoad(JavaVM* vm, void* reserved)
{
JNIEnv *env;
javaVM = vm;
jclass cls;
// LOGI("JNI_OnLoad called");
__android_log_write(ANDROID_LOG_ERROR, "JNI_OnLoad", "JNI_OnLoad
called");
if ((*vm)->GetEnv(vm, (void**) &env, JNI_VERSION_1_4) != JNI_OK) {
//LOGE("Failed to get the environment using GetEnv()");
__android_log_write(ANDROID_LOG_ERROR, "JNI_OnLoad", "Failed to
get
the environment using GetEnv()");
return JNI_VERSION_1_4;
}
cls = (*env)->FindClass(env, "com/examples/hellojni/HelloJni");
if(!cls) {
__android_log_write(ANDROID_LOG_ERROR, "JNI_OnLoad",
"initClassHelper: failed to get class reference");
return JNI_VERSION_1_4;
}
__android_log_print(ANDROID_LOG_ERROR, "JNI_OnLoad", "FindClass->
%p", cls);
jmethodID constr = (*env)->GetMethodID(env, cls, "<init>", "()V");
if(!constr) {
__android_log_write(ANDROID_LOG_ERROR, "JNI_OnLoad",
"initClassHelper: failed to get constructor");
return JNI_VERSION_1_4;
}
__android_log_print(ANDROID_LOG_ERROR, "JNI_OnLoad", "GetMethodID ->
%p", constr);
obj = (*env)->NewObject(env, cls, constr);
if(!obj) {
__android_log_print(ANDROID_LOG_ERROR, "MY-ALSA",
"initClassHelper: failed to create a object");
return JNI_VERSION_1_4;
}
obj = (*env)->NewGlobalRef(env, obj);
return JNI_VERSION_1_4;
}
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