FindClass cannot find custom Java class
I have a purely native app, as I use the android_native_app_glue and the entrypoint to my app is
android_main(..)
I also have a Java helper type class:
package abc.def.ghi
public class MyJavaClass extends Activity
{
public void callback()
{
Log.v(TAG, "In MyJavaClass");
}
}
I want to call the 'callback' method from native. I do so by:
jclass myClass = env->FindClass("abc/def/ghi/MyJavaClass");
if( myClass == NULL )
LOGI("myClass null");
jmethodID mid = m_pEnv->GetMethodID(myClass, "callback", "()V");
if( mid == NULL )
LOGI("MID null");
m_pEnv->CallVoidMethod(myClass, mid);
However this results in a message that myClass is null. My 'env' pointer should be okay because when I pass "android/os/build" in FindClass, it finds it, but cannot find my custom class.
In the LOGCAT, I see: "JNI Warning: Can't call Labc/def/ghi; callback on instance of Ljava/Lang/Class;"
I th开发者_运维技巧ink this means something is wrong with the first parameter of my CallVoidMethod.
I noticed in the other examples that most people perform their CallVoidMethod within a function with a signature that is generated by javah, and they use the obj
parameter in their CallVoidMethod
:
JNIEXPORT void JNICALL function(JNIEnv *env, jobject obj, jstring s)
However I cannot use this because my app's entry point is in native.
However this results in a message that myClass is null. My 'env' pointer should be okay because when I pass "android/os/build" in FindClass, it finds it, but cannot find my custom class.
This would suggest your custom classes are not on the classpath.
Note that when you create a VM you can pass options, including setting the classpath to include the current directory ( or wherever you like ).
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