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POAndroid: calling Java class from C++ Native Activity
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  1. POAndroid: calling Java class from C++ Native Activity
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    copied!<p>Java code:</p> <pre class="lang-java prettyprint-override"><code> package local.ttt; import android.graphics.Bitmap; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.Typeface; public class Text2Bitmap { static Bitmap getBitmap(String text,int fontsize) { Paint paint=new Paint(); paint.setStyle(Paint.Style.FILL); paint.setColor(Color.WHITE); paint.setTextSize(fontsize); paint.setAntiAlias(true); paint.setTypeface(Typeface.DEFAULT); int outwidth=(int)Math.round(paint.measureText(text)); Bitmap bitmap=Bitmap.createBitmap(outwidth,fontsize,Bitmap.Config.ALPHA_8); Canvas canvas=new Canvas(bitmap); canvas.drawText(text,0,fontsize-1,paint); return bitmap; } } </code></pre> <p>C source: </p> <pre><code> ... MY_ASSERT(vm_cached!=NULL); JNIEnv* env; jint res=vm_cached->AttachCurrentThread(&env,NULL); MY_ASSERT(res==0); jclass activityClass=env->FindClass("android/app/NativeActivity"); MY_ASSERT(activityClass!=NULL); jmethodID getClassLoader=env->GetMethodID(activityClass,"getClassLoader","()Ljava/lang/ClassLoader;"); MY_ASSERT(getClassLoader!=NULL); MY_ASSERT(nativeActivityObjHnd!=NULL); jobject cls=env->CallObjectMethod(nativeActivityObjHnd,getClassLoader); jclass classLoader=env->FindClass("java/lang/ClassLoader"); MY_ASSERT(classLoader!=NULL); jmethodID findClass=env->GetMethodID(classLoader,"loadClass","(Ljava/lang/String;)Ljava/lang/Class;"); MY_ASSERT(findClass!=NULL); jstring strClassName=env->NewStringUTF("Llocal/ttt/Text2Bitmap;"); jclass text2bitmapClass=(jclass)env->CallObjectMethod(cls,findClass,strClassName); //fails here MY_ASSERT(text2bitmapClass!=NULL); res=vm_cached->DetachCurrentThread(); MY_ASSERT(res==0); ... </code></pre> <p>it fails with:</p> <pre> W/dalvikvm(5614): dvmFindClassByName rejecting 'Llocal/ttt/Text2Bitmap;' W/dalvikvm(5614): threadid=9: thread exiting with uncaught exception (group=0x4002d560) E/AndroidRuntime(5614): FATAL EXCEPTION: Thread-10 E/AndroidRuntime(5614): java.lang.ClassNotFoundException: Llocal/ttt/Text2Bitmap; in loader dalvik.system.PathClassLoader[.] E/AndroidRuntime(5614): at dalvik.system.PathClassLoader.findClass(PathClassLoader.java:240) E/AndroidRuntime(5614): at java.lang.ClassLoader.loadClass(ClassLoader.java:551) E/AndroidRuntime(5614): at java.lang.ClassLoader.loadClass(ClassLoader.java:511) E/AndroidRuntime(5614): at dalvik.system.NativeStart.run(Native Method) </pre> <p>Any hint what I'm doing wrong, please?</p>
 

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