Android JNI Java is symmetric associated with C + + objects (JNI optimized design to ensure the stability of JNI calls)

Reprint please declare: Original translation from: http://www.cnblogs.com/xiezie/p/5930503.html

Android JNI Java and C + + objects establish symmetric Association 1. Java objects hold pointers to C + + objects

1. Create a variable of type int (such as int mobj) in the Java class to store pointers to C + + objects
2. In a local method that creates a C + + object (such as Mycplusobj), a pointer to a C + + object is stored in a Java variable (mobj)

 jniexport void   Jnicall Java_nativemethod ( jnienv  *env, Jobject thiz) {mycplusobj  *obj = new   Mycplusobj (); Jclass clazz  = (jclass) (*env).    Getobjectclass (Thiz); Jfieldid FID  = (jfieldid) (*env). Getfieldid (Clazz,  " mobj   ", "  i   ); ( *env). Setintfield (Thiz, FID, (jint) obj);}  

• If you want to get a C + + object, get a pointer to the C + + object through Mobj

  Jclass Objclazz = (jclass) env->getobjectclass (obj); // obj is the corresponding Java object " Mobj " " I "  = (jlong) env->*cplusobj = (mycplusobj *) p; // cplusobj C + + objects that correspond to Java objects

2.c++ object holds a reference to a Java object

1. Create a variable of type jint (such as Jint mobj) in a C + + class to store a reference to a Java object
2. Storing a reference to a Java object when creating a C + + object

   Jobject gthiz = (jobject) env->newglobalref (thiz); // thiz for Java objects (*obj). Javaobj = (jint) gthiz;

Android JNI Java is symmetric associated with C + + objects (JNI optimized design to ensure the stability of JNI calls)