关于Activity回调中的@override注释

Question

It seems in an Activity , for example, the onCreate() method, it does not make much difference if I have the @Override annotation or not. They both work. (As long as I call super.onCreate() inside the callback , it will call the parent class' method.)

Can someone tell me why we need to have the @Override annotation for life-cycle callbacks in Activity ?

I ask this because I tested without @Override annotation, my app still running successfully.

Answer 1

This is more like a good development practice.

If by mistake you want to override a method that doesn't exist in the super class (or interfaces implemented) you'll get an error.

Think that you want to override "onCreate" but you misspell it and write "onCreatee". With that annotation, you'll get an error. Without it, you'd end up spend a lot time trying to understand why your initialization method was not working properly.

Answer 2

The @Override annotation is used just to tell the compiler that we are overriding a method in our code. This is used for safety purposes to let the compiler know the aim of our function (ie to override) and if we are overloading a function by any chance, the compiler will return an error. Hence with this annotation, we can detect overloading mistakes easily.

Answer 3

Some already mentioned that it is very useful to catch potential bugs with wrongly spelled names.

I would like to add that it also shows which methods are new methods specific to your class and which are inherited from the parent class (or interface). It might not sound like much, but I personally find it very useful.

So you should always use @Override and configure your IDE to flag an error if you forget it.