有一点没看明白

[sofiaoffen]

// Create a new Java object
jobject newObj = jni::NewObject(env, "java/lang/StringBuilder", "()V");
jni::CallMethod<void这里为什么是void?>(env, newObj, "append", "(Ljava/lang/String;)Ljava/lang/StringBuilder;", "Hello, JNI!");
jstring result = jni::CallMethod(env, newObj, "toString", "()Ljava/lang/String;");