I’m just starting to learn OOP in Java, so this might be a dumb question. The Cat class extends Animal, they have a constructor, a static array, a method that fills the array, and a method that creates an object of the Moving class. On this created object of class Moving, the walk() method can be invoke…
Tag: extends
Why do I have to set AuthenticationManager twice
In my application I’ve implemented X.509 authentication I created the following class named X509AuthenticationFilter that extends AbstractPreAuthenticatedProcessingFilter provided by spring security by default. I added my own AuthenticationManager to the class And also included the following setter The …
Use Class as a method signature
In the method signature, I need a parameter that is any class type that extends from Collection (List, Set, etc), so I can return any of them. To try to achieve this I did use the following method: However when I try to use it like: The following error arises: I did search for an answer already solved in Stac…
How to properly add a value change listener to Map.Entry?
A project im working on currently requires me to ensure that while looping through a map’s entries, if Entry.setValue is called, it would trigger a value change event. I see I can try something like adding a listener into an extension of the Map class on the .put method. My question is, would entries be…
super.a = b instead of super(b)
I’m learning the super keyword and accidentally get this, here’s an example : The usual way to do this as in the tutorials is super(b) to reusing its parent constructor, but what is wrong with super.a = b? Answer When you write your class A like this: you overwrite the default constructor and in t…
Extending the Graphics class in Java
I need to extend the Graphics class in order to @Override some methods including drawRect(int,int,int,int) and drawRoundRect(int,int,int,int,int,int). However, I have no idea how to do that. This is what I’ve got so far: I get an error on class declaration line saying: myGraphics is not abstract and doe…