extend « 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 » extend 

1. Extending enum    stackoverflow.com

public enum myEnum {    
VAL1(10), VAL2(20), VAL3("hai") {
     public Object getValue() {
      return this.strVal;

2. How can I successfully extend Graphics in Java    stackoverflow.com

I'm trying to create a generic graphics export tool which works by implementing the Graphics interface and intercepts and interprets the calls to its various methods. However although I can ...

3. Why avoid the final keyword?    stackoverflow.com

In java, is there ever a case for allowing a non-abstract class to be extended? It always seems to indicate bad code when there are class hierarchies. Do you agree, and why/ ...

4. best approach to extend a class funcionality in java?    stackoverflow.com

for short, this could be paraphrased like "inheritance versus function library" for example, I'd like to add a method to the javax.servlet.http.HttpServletRequest that gives me the whole body, a getBody() method that ...

5. Classes not extending java.lang.Object    stackoverflow.com

While you create a user defined class in Java, you do not specify it as extending Object. But still the class is an Object. How does this work? How does javac ...

6. How to use a method from a class in another class without extending    stackoverflow.com

Sorry if my question sounds weird lol I'll try to explain. I have 4 classes: Karakter, Karakters, Orc, Human. Orc and Human both extend Karakter. Karakters is an ArrayList with Karakter ...

7. Difficulty in extending the third party class    stackoverflow.com

I have the following classes

         class A{
          private String name;

8. inheritance problem OOP extend    stackoverflow.com

If a Father is a Parent and a Parent is a Person and a Person has a Father I create the following:

 class Person{
  Father father;
 class Parent extends ...

9. imports and extends    stackoverflow.com

can any one explain " While we are importing a package we can use its all public functions, Then what is the use of extending a class ?" " I ...

10. Java "extending" an object    stackoverflow.com

I have only recently gotten back into Java programming and am currently stuck with a certain problem. I have an object of a certain type:

StandardClass stdClass = (StandardClass)request.getAttribute(ATTR);  
But ...

11. Java - Can you cast an object into a class it doesn't extend?    stackoverflow.com

Another way to ask the same question is, given 2 classes A and B, is it synonymous to say: "Object A can be cast into B" and "Object A is a ...

12. Correct way to extend a class so I can override equals()    stackoverflow.com

I have a class in a package that I cannot alter. This class does not override Object.equals() and having a different implementation of equals would really make my code cleaner. I know ...

13. what does following Java line of code means    stackoverflow.com

I found this class in magnolia CMS source which uses class definition I am not yet familiar with. Could anyone having knowledge about usage of the following code style explain to ...

14. Is it bad practice to call super() in a class that doesn't extend anything?    stackoverflow.com

Quite often I see people explicitly calling super() in a class that doesn't explicitly extend anything.

public class Foo
  public Foo()

    //do ...

15. Xcode cannot find a java class which I'm trying to extend    stackoverflow.com

I'm working on a Java project which was written by someone else. This person made a hierarchy of folders inside the 'src' folder. I've added a new java class into one ...

16. Why extending an Interface does not make it's method to return more precise types?    stackoverflow.com

For example if we have a class Person and a class Student extends Person. The we may have:

public interface PersonQueryBuilder<T extends Person> {
    PersonQueryBuilder<T> withName(String name);


17. Java Interface Inheritence and Extending    stackoverflow.com

Imagine you are working on a mature product and a new search feature is requested that is required for 50% of your product. Now assuming you have an established interface ...

18. in java how to extend an implementation of interafce?    stackoverflow.com

I have an interface and I am promised by someone to provide its implementation. I have to now design a class s.t I can extend "someone's" implementation. However I do not know ...

19. How can I extend a static final guava utilities class?    stackoverflow.com

When I've used common-collections I've done custom extensions to those utils like:

class MyCollectionUtils extends CollectionsUtils {
static myutilityMethod()
static removeDublicate(..)
static myPredicate(...)
In that case I have all functionality from CollectionsUtils and my extension ...

20. Extending an inner interface?    stackoverflow.com

I got a simple question: Why does Eclipse scream about implementing these two interfaces?

public abstract class Gateway implements IPlayerity, IItemity {
    public interface IPlayerity { ... }

21. Java -- referencing a method in different class    stackoverflow.com

I am coming from C programming, so I m new to the OOP concept. My question is this: I am trying to test a bunch of modules, so I decided to ...

22. Extending variables and covariant return types    stackoverflow.com

I was testing out covariant return types and came across this problem.

class Vehicle {

    int i = 3;
class Car extends Vehicle{

    int i = ...

23. Best way to create the behavior of an extendable Enum in java    stackoverflow.com

I want to create something that resembles an extendable Enum (understanding extending Enums isn't possible in Java 6). Here is what im trying to do:
I have many "Model" classes and each of ...

24. Actionscript overriding methods in extended interfaces vs Java?    stackoverflow.com

I am much more familiar with Java's semantics of class and interface than with Actionscript semantics, but I have an example of some code that works in Java and doesn't work ...

25. Not getting the correct values for variables in extended class    stackoverflow.com

Just doing a quick edit up at the top of my post. The question is if i extend a class and both classes have the same variable why is the extended class ...

26. Achieving inheritance without extends    coderanch.com

Hi, This is the question asked in interview to my friend. He didn't know the answer for this and asked me. I told it may be(I am not sure, that why I asked in this forum to clarify) using the anonymous class we can achieve(I think). I read about anonymous class in the event handling. I don't know how to use ...

27. Inheritance question when I have class A extends class B extend baseclass    coderanch.com

Hi, I have a question on inheritance. Say I have 3 classes Class Animal { protected boolean isAlive = true; public Animal(){} protected String toString (){ String s= "isAlive = "+isAlive; return s; } } Class Mammal extends Animal{ protected boolean givesBirth = true; public Mammal(){} protected String toString (){ String s= "givesBirth = "+givesBirth+ super.toString(); return s; } } Class ...

29. Why Java didnt have mulitple inheritence via extending class    coderanch.com

Extending multiple classes was primarily left out in order to keep Java "simple." The main problem which programmers could encounter with being able to extend multiple classes is the Diamond Problem (which I prefer to call the Dastardly Diamond of Death) When extending multiple classes it creates a serious possibility of ambiguity in your method calls/classes. The reason why multiple interfaces ...

30. problem with two extends of Inheritance    java-forums.org

Hi guys, I am currently doing a problem that is as follows ( I have not yet put in the Main method): Define a class named Payment that contains a member variable of type double that stores the amount of the payment and appropriate accessor and mutator methods. Also create a method named paymentDetails that outputs an English sentence that describes ...

31. differences between "extend" and "interface" inheritance?    forums.oracle.com

aha so my interface one can trick to do multiple inheritance.. am I right? I have been developing in C++ for a long time. And have recently started developing in JAVA. So am going through it fast Thank you so much. Multiple inheritance is a problem in most cases.. Am I right?

32. One more question on inheritance -- using methods in extending class    forums.oracle.com

Accessing fields in a superclass is a hideous idea. Whenever I see a protected field, it sends shivers down my spine. Same pretty much goes for protected methods, come to think of it! In both cases - and indeed with concrete inheritance in general - you've got a dependency on a concrete class, a dependency on it's implementation details. This is ...

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