class « Inheritance « Java Class Q&A

Java Class Q&A
1.abstract class
2.Base class
3.class hierarchy
4.class name
5.class version
14.equal method
15.extend Class
19.inner class
21.main class
26.object reference
28.parent class
31.Private Field
35.Static Class
39.Wrapper Class
Java Class Q&A » Inheritance » class 

1. Classname + $ . What causes it?

I have a class A. I have a reference ref of class A pointing to an object of type x. What kind of object makes ref.getClass() print A$1 ? And what does ...

2. Java classes inheritance

Here, it says that:

This gives MountainBike all the same fields and methods as Bicycle, yet allows its code to focus exclusively on the features that make ...

3. How to deal with interchangable base classes in Java

I have an issue with some inheritance I'm doing. Basically, I have an abstract class called LineCalculator, which, as it suggests, calculates lines of an equation. From there, I inherit this ...

4. About Java Assignment Operator

If i define

class A {

public int a;
public float b;
public A() { 
a = 10;

class B extends A {

public B() {
a = 2;

class C extends A {

public C() {
b = 2.0f;
And in ...

5. Java inheritance

Why does is print last "I'm a Child Class." ?

public class Parent
    String parentString;
    public Parent()

6. How do I call a class from another class(not inheritance) in Java?

I can't remember what it's called when another class's method in java for example in a main class you call the scanner class to scan in user input?

7. Java class initialization conundrum

I am using NetBeans' GUI Designer to create some JDialogs, which I then subclass from my own EditorDialog class. Before I go further, consider this sample code:

class MyDialog extends EditorDialog {

8. Java inheriting from two classes

I'm using an interface in java, pdj, that comunicates my classes with PureData. In order to do so, my classes have to extend a given class (MaxObject). While designing my class, ...

9. Class Self-Reference

I have the following code. The angle function needs some information from the class it was called from. What's the best way to do this?

class MyScannedRobotEvent extends robocode.ScannedRobotEvent {


10. Deprecate class inheritance only

I would like to deprecate only the extension of a given class, not all the methods and fields contained within a class, using the @Deprecated annotation. That is, a warning will occur ...

11. Java Utility Classes and Extension through Inheritance

I have a utility class with some static methods which I use in some places around my code. I am facing a problem now. I want to replace the functions in ...

12. Inheriting classes for a text-based game

I'm trying to create a text-based game for class and i'm stuck on trying to get my main class, GCPUAPP, to read from my Artifact class. Here's the code i've inputed for ...

13. Classes in Java

I am new in Java so it will be a newbie question, here it is: I have a class Airplane. But I must have different Airplanes (like PassengerPlane or CargoPlane) Then I have ...

14. Java "trick", redefining daughter class member

I'm training for a Java exam, and I've come across something I don't understand in last year subject. Here is the code

class Mother {
    int var = 2;


15. Haskell type class hierarchy in Java

I write a library with Java interfaces resembling Haskell type classes, and abstract classes implementing all "derivable" methods (e.g. Monad.join can be written using >>= and return). This is ...

16. Sharing data across 2 classes

I have to share a String[] across two classes. One class sets the array and the other gets the array. I made four classes. One contains the Array at superclass level ...

17. Runtime determination of base class at runtime in Java

I have two classes, one which is hardware-dependent and one which is not (let's call them HardwareDependent and HardwareIndependent respectively). The Hardware dependent class extends the hardware independent class. ...

18. Why do we use Base classes in Java

While doing a desing/framework it is a usual practice to have a Base Class for Value Objects, Services, DAOs etc. For example if we create a new VO, it extends from ...

19. java class inheritance

I have a superclass and child classes.
I am in a child class and in a super method I want to check if a certain parameter object is of the certain child ...

20. Adding new functionality to a non extendable class java

Is the a way to add a new functionality to a non extend-able class i.e(final class ) in Java , I know a way to add a property to it using ...

21. inheriting a class

22. class inheritance details

Of the three classes you've mentioned only two are legal (also watch the spelling on implements) class A extends class B { } class A implements class b{ } In the cases above extends denotes that you are inheriting from a class. implements denotes that you are using an interface. Check out the java tutorial for more information on interfaces. Also ...

24. class inheritance

I have written code similar to what is below. Can anyone explain to me why the instance of class1 created in class2 can't be referenced in class3? class Class1 { private int x; public void setX(int x) { this.x=x; } public int getX() { return x; } } class Class2 { static int blob; public static void main(String[] args) { Class1 ...

25. Class inheritance.

26. Class inheritance

I have the following scenario: We have a center which is running 3 types of courses: Cooking, Sewing and Writing. Now we want to make sure that our class hierarchy will forbid a user from creating a generic type of course (i.e. not a cooking, or sewing or writing course). Can anybody suggest that how should we implement this?

27. Java classes and inheritance

Hi Go4Expert o/. I already introduced myself here, but, I lost my account abilondias, and here I am to shot up a question. I am developing a Java Web application and need some instructions. There are 4 classes : Functionary, Donor, Receiver and Manager. All of them have almost the same atributtes. Should I use Java Inheritance or make a class ...

28. Help with classes and inheritance task.

Hi i have the next task to solve. A bank holds different types of accounts for its customers: Deposit accounts Loan accounts Mortgage accounts Customers could be individuals or companies. All accounts have customer, balance and interest rate (monthly based). Deposit accounts are allowed to deposit and withdraw money. Loan and mortgage accounts can only deposit money. All ...

29. Value of one class not updated in another . Inheritance?

Hi, I am developing a program in Netbeans that updates values of a JSpinner when a socket connection comes in. In netbeans, when you create a java desktop application, it creates a Main java class (in my case and the GUI where all Swing stuff is (in my case So I went to the main class and did PolAntView ...

30. Class inheritance question (code provided)

Hi guys! I have this code that I am working on, and when I try to run it, the program goes into a non ending loop and eclipse stalls........ I will post the first class - which is HourlyWorker, and I am supposed to derive a subclass called OTWorker. Hourly worker is derived from "Employee" class, so I hope that does ...

31. Inheriting two kinds of Lists into one Class

I want to know if its possible to implement an ArrayList and a LinkedList into a single class ?. What I exactly want to do is this : * Perform addition and removals of elements from the List using a LinkedList. * Perform traversals and searching of elements in the List using an ArrayList . I know this is possible by ...

32. Class Inheritance Cast

33. Java Class Inheritance Problem

import java.awt.*; public class Building{ int Tile_x; int Tile_y; int Health; Image Picture; Renderer p; public Building(Renderer parent) { p = parent; } public void inital(Image temp_image, int Temp_Tile_x, int Temp_Tile_y, int temp_Health){ Tile_x = Temp_Tile_x; Tile_y = Temp_Tile_y; Picture = temp_image; Health = temp_Health; } // public void draw(){ // p.Buffer.drawImage(Picture, p.Tiles[Tile_x][Tile_y].x, p.Tiles[Tile_x][Tile_y].y, this); // } }

35. inheriting from two different classes

Well this is wrong for two reasons. Firstly it was a precondition that A and B didn't have any common supertypes. Nothing says you cannot introduce such supertypes as part of a solution. Secondly I did not introduce any such common supertypes. Both AI and BI are completely separate. CI must inherit both though. If that's not allowed inheritance cannot be ...

36. Inheritance and nested classes

37. Class inheritance

Hello, I have a kind of conceptual question. Is this conceptually correct to extend a class and not to override any its method? Taking a java collection as an example, would it be OK to create its subclass and just add a couple of methods, leaving all the collection behaviour untouched? Or it would be better design to wrap this collection ...

38. inheritance class not working

39. Simple design question (class inheritance)

I'd suggest taking a step back, and ask, what's going to be invoking that 3-arg doThis method on B? Generally you overload methods like that for polymorphism purposes so that the caller doesn't need to know what subclass it's getting. The caller just knows that is has an object of type A and by calling doThis, it will do the right ...

40. Inheritance in the java class heirarchy

ok two questions. 1. in the java class heirarchy, do the subclasses inherit all of the concrete methods from the superclass, that the subclass has not overridden. Or just some of them as Sun has deemed necessary? 2. In the situation where you have a custom class that extends another class, can you invoke all of the constructors in the superclass ...

41. Can i make inheritance on these classes?

Here i still have to specify a specific class statically, i want it dynamically. I have ProductLists class, which holds the add(), getName() and so on methods. And its all good. But then i want TypeList, BrandList and CategoryList classes to be subclasses of ProductLists class. Because they all hold different kind of information. TypeList class holds for example "Baseball" and ...

42. Dynamic loading of a class at runtime with known inheritance

My apologies, I worded that wrong. My current approach (the one given in the code) selects the root package folder. However, what I want to be able to do, is to simply select a single class file. The current code just makes some assumptions so that I can at least see results in the program. As you said, if the root ...

43. Sequence of Class Loading in inheritance

Is it possible to send a COMMAND to underlying command prompt from JVM? Actually i want to clear the console on which jvm is running. (in simple language i want to send 'cls' command to console). I am using Windows XP & Win2k3 Enterprse server. No. When you open a console window that is an application. In general the term "shell" ...

45. Inheriting Properties from Two Classes

I need to make a bunch of classes for an assignment. Class Person stores the first and last name of the person. Class Student extends from person and also stores the student number. Class Employee extends from Person and also stores the working hours and salary of the Person. Class Instructor extends from Employee and stores nothing extra. Finally I need ...  | Contact Us | Privacy Policy
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