I want to create a common service and common request as shown below: Then implement this service as shown below: However, although CompanyARequest is inherited from CommonRequest, createOrUpdate method throws “Method does not override method from its superclass” error. On the other hand, if I use …
Tag: inheritance
Java Inheritance, instanceof, casting – how to accept a children object throught parent object?
I have three classes: (Parent) Animal, (Child) Bird & Monkey Monkey has weight & two pet Animals, which can be another Monkey, or bird Bird has weight & a name (weight, name) Together, they form a TREE, where leaf nodes are Bird, and non-leaf nodes are Monkeys (SEE VISUAL) While recursively traver…
How to write constructor where the types are from another class in Java?
I’m doing a UML diagram for a Connect four game. It is a two-player connection board game, in which the players choose a color and then take turns dropping colored discs into a seven-column, six-row vertically suspended grid. I have a problem with the UML Diagram. The class game has 2 variables that cam…
Should I keep an enum attribute when it has always the same value as a result of a new inheritance?
I have these classes: Imagine that for some reason, I need to make Car a superclass for two new classes: CombustionCar and ElectricCar. One of the new requierements is that ElectricCar’s brand attribute must be always TESLA value and not any of the other ones values. I’ve thougth some solutions: I…
Printing String Attribute Inherited from SuperClass shows Null
I am extending a class and using the super keyword to in my subclass constructors. However, when I attempt to print the inherited attribute String. It returns null } So when I create a TrueFalseQuestion object and call its getQuestion() method, I get output: null True/False? Why is it not printing the questio…
How to inher variables values from one page to another in java?
I’m new to java and I’m stuck with this. I have one BasePage class that contains a “global” List and an int value like this; Moreover, I’ve two classes that extend that page; And other: Then, when I access “stringList” and “number” after calling that who c…
If only one object is created during inheritance then what is super keyword referencing to?
In the following code, what is super keyword referencing to? If no objects/instances of super class are created, then what is super keyword referencing to as it is a reference variable and supposed to reference super class instance? Answer Note that super is a bit different from this, in that super is not a p…
Why can’t I add a type parameter to an overriding method?
I need to implement a method from a class Foo, in my subclass Bar: As you can see, my method would benefit from a type parameter: (I could also use raw types because I know it’ll work, but everything I’ve read says you really shouldn’t do that) Unfortunately, this is illegal – my metho…
Composition or Inheritance for classes with almost similar implementations but different input and outputs for methods?
I have the following classes, which have quite similar method implementations. Only the classes’ method inputs and outputs seem to be of different types. When I put it like this, it sounds like a case for inheritance, however, the fact that the inputs and outputs are different and are related to two lam…
Java Inheritance: Paint Program only shows a black screen but doesn’t have any errors
I know its a lot of code but I could really use some help identifying my problem. Thank you! I am just now being introduced to inheritance and am challenging myself with this application to a painting program. The program is meant to draw different shapes (lines, oval, rectangles, etc.) and I used trial and e…