Using Inheritance,dose child class have father 's inner class?

using Inheritance,dose child class have father 's inner class?

as near as I can tell, the conversation so far has been:
When I extend a class, does the subclass inherit the parent class's inner classes?
followed by
Never mind, i ran a test and found out the answer, sorry for my English.
hope that helped.
Lee

Similar Messages

Preventing Child Class Dependency when using conditional disable to specify Class in Development Environment

Hello
I am developing an application which I would like to execute on both normal and real-time systems using LabVIEW Proffesional Development System 2012 SP1
To control how the application interacts with the user, I have created a class which defines the type of user-interface behaviour which should allow me to have nice dialog boxes when the system is executing on a windows machine and have no dialog boxes (or other non-Real-Time friendly code) when operating on a real-time target.
The parent class is the code that is suitable for Real-Time and the child class is the one with dialog boxes.
To control which class is loaded, I have a conditional disable structure. This will work fine when the application is built into a executable or real-time executable but the problem arises when I want to use the code during development on the real-time target.
I find that with the application under a real-time target (RT PXI), the correct conditional-disable case is activated so the parent class is used, but the child classes are also listed under the dependancies - I pressume this is because they exist on the block diagram in the disabled case of the conditional disable diagram.
This means that I cannot deploy the code to the Real-Time target as it is unhappy with the child class code - even though this will never be run.
To save posting my real project, I have created an example with a Parent and Child class and a Conditional Disable Flag called "CLASS" to demonstrate the problem.
If you run Test.vi you will see that the Child class still gets locked (i.e. is a dependancy) during execution even though it is not called.
So - basically my question is: Is there anything I can do about this or will I just have to do-away with the conditional disable and just put the correct Class constant on the block diagram during testing?
Thanks in advance
John.
Solved!
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Attachments:
Example Proj.zip ‏18 KB

I feel your pain. I ran into a similar problem a short time back.
Apparently Official NI stance is that you need to put a conditional Disable structure IN EVERY ONE OF YOUR CLASS VIs. In the Windows VIs, you simply have an empty conditional disable case with the windows code in an appropriate other case and vise versa on the RT.
I too would much prefer the method you describe...
Say hello to my little friend.
RFC 2323 FHE-Compliant

How to get the child class in inheritance?

hi,
if I have a store for renting videos .. and I have Video class (parent) and two (child) classes DVD and Cassete which they are extend the video class.
And the user wants to rent a DVD which is the child, how do I do that? can I write just getDVD() as simple as that or maybe I need to use a keyword like "getinstance of DVD " or something I don't know how to do this.
class Video have attributes like title, date of production and director.
I'm not good in inheritance help please.
thanks

georgemc wrote:
DrLaszloJamf wrote:
Post a SSCCE: http://mindprod.com/jgloss/sscce.html
You're not the boss of me ;-)Actually, I haven't stopped to count, but most of the time the poster never bothers to write a sample program. If fact, if I weren't such a softie, I would make that an absolute requirement for any further help. Too often, you are just shooting in the dark and 50 replies later the question is still vague.

Inheritance problem with parent class calling child class

I have a problem with inheritance with a parent class calling a child class method. Below is the example pseudocode code and my problem:
public abstract class A {
    protected void function1 ( ) { }
    protected void function2 () {
         //calls function1();
         function1();
public abstract class B extends A {
    protected void function1 () {
         // do stuff
public class C extends B {
    protected void function1 () {
        // do stuff
        super.function1 ();
}I have an object instance of class C created and its function2() is invoked.
My problem is, while in function2(), which belongs to abstract class A and the method call to function 1() is called, the call invokes the function1() of class B. Shouldn't the call invoke function 1() of class C instead? And then function1() of class B will be called after due to the super.function1(). It's not behaving like I thought it would.
Edited by: crono77 on Jan 10, 2008 8:13 PM

Nevermind, i found my error :)

Calling father from the child class?

Hi...
And I want to learn how to:
public class FATHER{
int SAMPLE=0;
FATHER(){
Child mychild=new Child();
class Child{
Child(){
// I am child and I want to set my father's(who created me) SAMPLE var...
here is a small example.. I could not reached fathers variables in the child.. there must be an easy way to do that ..
Thanks ...

Actually, why would that happen?Because the father tries to create a child, itwill
become recursive.
KajOh, so it will become recursive due to the
constructor in the Father class?Nope, because of the ctor of the child class because it'll call either
implicitly or explicitly the father's ctor again.
kind regards,
Jos
ps. see for yourself:class Father {
   private class Child child;
   public Father() {
      System.out.println("father ctor");
      child= new Child();
public class Child extends Father {
   public Child() {
      System.out.println("child ctor");
}

Fill Child Class using C# and SCOM dlls

Hello,
We have requirement to run some c# tool and that tool insert the data to scom database. Can anyone please help me to achieve this.
the structure is as below.
1. Base class (this class is having "Source" as Windows.Computer)
and Base class will be filled by Discovery
2. Child class (Base class is the "Source" for this child class)
now the c# tool has to fill the Child class.
Thanks in advance.
regards,
Mahadevan.G

Just try to get property Base.
Vladimir Zelenov | http://systemcenter4all.wordpress.com

Fastest way to create child class from parent?

As the subject states, what do you folks find is fastest when creating child classes directly from the parent? (esp. when the parent is in a lvlib) I thought I'd post up and ask because the fastest way I've found to get working takes a few steps.
Any suggestions ae appreciatized!
-pat

Thanks for the quick response Ben!
Yea, I apologize, in your response I realize my OP was more than vague haha (it hapens when you get used to your own way of doing things I guess huh)- I'm trying to create a child from a parent so that it has all of the methods that the parent has.
In order to do so I currently have to open and close LV a few times during my current process so that vi's in memory dont get mixed up- Currently I save a copy of the parent class in a sub dir of where it is saved, close out of LV, open the new 'copy of parent.lvclass', save as>>rename 'child class.lvclass', close LV, and open up the project to 'add file', then right click>>properties>>inheritance.
Is this the only way to do this?
Thanks again!
-pat
p.s. I'm tempted to steal your cell phone sig, hope you dont mind haha good stuff!

Executing a child class from parent.

Hi, well, I have this parent class which I need to execute a method from a child class to get a significant part of the thing get started. Is there anyway for me to accomplish this or a workabout? Thanks..

Sure.. I have this method in the class logic:
     public void createLocation() {
          try {
          classCoord coordSet = appinterface.decodeFile();
          int areaNum = coordSet.areaNum, cellNum = coordSet.cellNum, signalStrength = coordSet.signalStrength, receiverId = coordSet.receiverId;
          String dateTime = coordSet.dateTime, userName = coordSet.userName, location = calLocation(areaNum, cellNum);
          boolean validity=calValidity(signalStrength);
          classLocation locationObj = new classLocation(this.type, userName, receiverId, validity, location, dateTime);
          appinterface storeLocationObj = new appinterface();
          storeLocationObj.storeLocation(locationObj);
          catch (IOException ioException) {
               appinterface.displayMessage("Logic Error: " + ioException);
          catch (ClassNotFoundException classNotFoundException) {
               appinterface.displayMessage("Logic Error: " + classNotFoundException);
     }I need to execute this method halfway in the class appinterface, the logic class inherits from appinterface cuz I need to make use several methods from it. Is there any way to solve this somehow?

Parent class private data accessable in Child class?

Hi!
I thought that this would be obvious, but my search foo fails me. Hopefully someone would be kind enough to answer my newbie LVOOP question.
I have a a parrent class. This parrent class contains a cluster of class private data. I setup all the accessor methods to this data. I create a child class that has functions that need to access data stored in its parrent class. Its inheritence is set, but when I try to unbundle the class data all I can seem to get to is what is setup in the child class' data cluster.
I've watched a video and it looked like the data cluster magically appeared and was accessable through the children methods. What am I missing?
Thanks for input!
-nic
Solved!
Go to Solution.

Nickerbocker wrote:
Well, that makes sense.
One other quick question. Is the procedure, New->"VI for Override..." from the context menu of my child class the only way to create a method that overrides the parents method? Where is the property that defines this newly created VI as overriding my parent's VI? Can I simply create a VI that is named the same and it have the same effect?
That is the only method I use but I believe if you get all of your icon patterns and terminal marking as dynamic and all of the other rules, you should be able to do the same thing by hand (I base this guess on the fact I messed with those things and broke my ever-rides).
The only thing I think has to be done from the project (scripting aside) is to set-up the inheritance.
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

Class override, how to create the child class and then the base class

I started to write a program for a smart DMM, the problem is every version of the DMM the company change the communication commend.
My idea is to write a child class for every DMM version and every SubVI of the child will override the base class SubVI.
My problem is, i want first to create one child class and after i will see every thing is work, start to create the base class. that way i will see if am thinking the right way.
My question is
How can i create a child class and then create the base class and configure the SubVi of the child class to be Override of the base class?
I tried to search in the property of the class but i didn't see nothing.
Thanks
Solved!
Go to Solution.

This can be done and I've done it on occasion.
You simply create the base class with the dynamic dispatch methods you require (connector panes need to be identical to thos of the child class).
Then set the inheritance of the class to inherit from this base class. If your method is defined as a dynamic dispatch method in the parent, you'll most likely now have some errors (unless your child method was already DD in which case you might just be OK already).
To change the inheritance of a class, right-click the properties of the class in your project and select properties. I believe the ineritance tree is at the lower end of the properties. Click on the "change inheritance" (or something similar) to choose the class from which you now wish to inherit.
Say hello to my little friend.
RFC 2323 FHE-Compliant

Why to use inheritance when import is sufficient

The import directive tells the compiler where to look for the class definitions when it comes upon a class that it cannot find in the default java.lang package. After an import statement has been included in our program we can use the methods related to that class as required and we are not required to give the fully qualified names.
In inheritance we extend a base class into a derived class so that the features and methods of the base class are available in the derived class which facilitates reusability. As per my understanding the same thing is facilitated by import statements. If it is so, why are we using inheritance if it can be done with the use of import statements?

Import statements and inheritance are completely different things.
Import statements tell the compiler how to expand brief class names into fully-qualified class names. It has nothing to do with the functionality of the code.
Inheritance changes the identification and functionality of the classes, and thus the functionality of the code.
Maybe you're really thinking about composition/delegation vs. inheritance. Composition is when a class has another class as a part of it, and delegation is when the class sends some of its work to the other class. You can have an object-oriented system without inheritance of implementations, using composition instead.

Setting final Instance variables in Child Classes

Hello:
Is it possible to declare (not initialize) a final variable in an abstract parent class and set it in a non-abstract child class.
An example for clarification.
I have an abstract parent class (call it P) and two child classes (call them (C1 and C2). There is common processing that goes on in P. This processing uses a variable called x. C1 will set x to equal 10 and C2 will set x to equal 20. Can I declare x final in the abstract class P and set it in C1 and C2
This is impossible right? I know some other languages allow this behavior so I just wanted to make sure that Java does not support it.
Thanks
Johnny

Why don't you just try it out? Though I'm pretty sure it won't work, as it should expect all constructors of the abstract class to set it. But you could either let there be an overridden method that returns the appropriate value for the sub-class:
abstract class P
abstract protected int getTheValue();
class C1 extends P
protected int getTheValue() { return 10; }
class C2 extends P
protected int getTheValue() { return 20; }
}

Easy One: Constructor of Child Classes

Hello. I am new to the java language and i have a question.
I want to make a Class Vehicle which should have the following variables
static int id;
static long color;
static String brand;
static Boolean rented;
static String location;
Now i want to make a Child class called 'Car' which should have the .location set to "land" by default.
I want to also make a Child class of 'Car' called 'Bus' .
Now the problem is with the constructors. I want that when i create a class Bus that the .location is set to "land" automatically and not with user input. This means it will call the constructor of 'Car' and not 'Vehicle' which sets .location to "land"
I tried to do so but it tells me 'Constructor Car() was not found' .
I want the constructor of Car define the .location="land" but the constructor of Bus will not have the .location argument because
it is set to "land" by default?
Please help !
thanks
code follows:
package map_exercise;
* Title:
* Description:
* Copyright: Copyright (c) 2003
* Company:
* @author
* @version 1.0
public class Vehicle {
static int id;
static long color;
static String brand;
static Boolean rented;
static String location;
public Vehicle(int myid,long mycolor,String mybrand,Boolean isrented,String mylocation) {
this.id=myid;
this.color=mycolor;
this.brand=mybrand;
this.rented=isrented;
this.location=mylocation;
package map_exercise;
* Title:
* Description:
* Copyright: Copyright (c) 2003
* Company:
* @author
* @version 1.0
public class Car extends Vehicle {
public Car(int myid,long mycolor,String mybrand,Boolean isrented) {
super(myid,mycolor,mybrand,isrented,"land");
package map_exercise;
* Title:
* Description:
* Copyright: Copyright (c) 2003
* Company:
* @author
* @version 1.0
public class Bus extends Car {
public Bus(int myid,long mycolor,String mybrand,Boolean isrented) {
}

I agree with NadjaS about the general remarks on the use of static vs. instance variables.
Anyway, if you really need to keep the variables at the class definition level, you can initialize them through the static initializer constructor within the "Car" class itself, i.e. something like this:
public class Car extends Vehicle {
static {
location = "land";
}without necessarily calling the super constructor.
The message "Constructor Car() was not found" is due to the fact the the only Car class constructor has four parameters - hence a completely different signature - and there is no constructor without parameters at all.
Hope this will help.
Bye

When to use inheritance and When to use Composition

java support both inheratiance and composition .I also know "is a" and
"has a realitionship" but there is always a problem with me to understanding whethere i have to use extends or having a object of a class has a member of othere class.
and also "A pure OOP must support polimorphisim,inheretiance,encapluction,Abstraction and Composition" correct me if i am wrong
thank you and have a nice day.

Bruce Eckel, author of Thinking In Java, has this to say about composition vs. inheritance:
When deciding between inheritance and composition, ask if you need to upcast to the base type. If not, prefer composition (member objects) to inheritance. This can eliminate the perceived need for multiple base types. If you inherit, users will think they are supposed to upcast.
Choose composition first when creating new classes from existing classes. You should only used inheritance if it is required by your design. If you use inheritance where composition will work, your designs will become needlessly complicated.
Bill Venners: Composition versus Inheritance
Use inheritance (of implementation) only when the class satisfies the following criteria:
1) "Is a special kind of," not "is a role played by a";
2) Never needs to transmute to be an object in some other class;
3) Extends rather than overrides or nullifies superclass;
4) Does not subclass what is merely a utility class (useful functionality you'd like to reuse); and
5) Within PD: expresses special kinds of roles, transactions, or things.
-- from Java Design: Building Better Apps and Applets (2nd Edition), by Peter Coad and Mark Mayfield

When to use inheritance and when not to?

I've just been trying find out when to use inheritance and when not to use inheritance? I know that inheritance gives advantages such as code reuse and maintainability. But when are their times not to use inheritance that may effect the design of a project?
Also when should one consider aggregation over inheritance(is-a relationship)?
thanks,
plandis

Hi
Answering this question usually requires a few books, so, I'm sorry, it's not really as simple as choosing between using a screwdriver vs. a hammer.
But, very short, inheritance should ideally only be used when there exist a strict 'is-a' relationship. However, sometimes it may be clever to inherit when you have a 'is-almost-a' relationship... And sometimes this is a stupid move. This depends on the context/circumstances.
Aggregation is normally considered a 'has-a' relationship, thereby differing clearly from inheritance. The old 'car' model says "a car is-a vehicle and has-some (at least) wheels."
The wheels are aggregated to the car class, that itself is inherited from vehicle.
However, this is just a good rule-of-thumb and there may be circumstantial reasons for not following these guidelines.

Using Inheritance,dose child class have father 's inner class?

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