Why does AndroidJavaClass exist?

Question

AndroidJavaClass just inherits AndroidJavaObject, and has no overrides. What is it use?

Answer 1

Answer by Bunny83 · Jan 06, 2017 at 05:10 PM

I answered this question already on your comment over here. As i said both classes serve a different purpose. It does have an override, the constructor.

AndroidJavaClass is a wrapper class for a native Java class. All the constructor does is finding the Java class with the given name.
AndoidJavaObject is a wrapper class for a native Java class instance. The constructor of this class does create an instance of the Java class and serves as wrapper for that class instance.

Both classes have a distinct usage.
AndroidJavaClass allows you to access a Java class type and access static members of that class. In this case no instance of that class is created.
AndoidJavaObject will create an instance of a Java class and allows you to access instance members as well as static members.

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brunoleos · Jan 09, 2017 at 03:19 PM 0

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The constructor of AndroidJavaClass partially initializes the base class (AndroidJavaObject), as it lets a null pointer for the class instance (the object). So the specific need for AndroidJavaClass is just to get an exception if I try to access an instance member?

If that's the case, I see a bad architecture for AndroidJavaClass. I'm worried if I can have all the functionality using just AndroidJavaObject, which would make the code simpler and intuitive.

Bunny83 brunoleos · Jan 10, 2017 at 02:30 AM 0

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Are you sure you read my answer carefully? When you create an instance of "AndroidJavaObject" you actually create an instance of the wrapped class inside the Java V$$anonymous$$ which is not the case when you use AndroidJavaClass. You seem to always concentrate on the irrelevant things and ignore the actual reason for the two classes. You can not use AndroidJavaObject directly to get access to a Java class without creating an instance of that Java class.

Also keep in $$anonymous$$d that both classes are just wrappers around the JNI bridge. You don't have to use those two classes at all, but they simplify the usage of the JNI bridge by a lot. But if you want, just use AndroidJNI directly. Though most methods of AndroidJavaObject and AndroidJavaClass would require several JNI calls.

brunoleos Bunny83 · Jan 10, 2017 at 12:47 PM 0

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Hi Bunny83, I'm carefully studying this problem, and your comments, you don't need to worry about this. The case is that AndroidJavaObject also wraps a java.lang.class object. This is accessible with GetRawClass(). I've also inspected the initialization of the returned wrapped java.lang.class object, and it is the same for constructors with string argument (m_jClass = AndroidJNI.NewGlobalRef(androidJavaObject.GetRawObject())).

So it seems the use forAndroidJavaClass is when I don't want to have a java.lang.object initialized, as you suggested. It makes sense if initializing this object is expensive, and if you don't have already an AndroidJavaObject initialized.

But... An AndroidJavaObject is initialized in the constructor of AndroidJavaClass, which break your comments.

Why does AndroidJavaClass exist?

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