If a dto extends from a super class is this a good design ?

I am confused whether to extend my dto from another dto ,I wanted to seperate the common properties like the pagination and sort form all my search dto's, if I do this all my search dto's will extend from common dto ,but because dto is just a pojo is it good to create inheritance in DTO's ?

Since a DTO should just contain fields and minimal logic you should have less problem with inheritance for DTO than other classes.
Is there a specific doubt you have in this regard?
I suggest you take the approach which seems simplest to you.

Similar Messages

Calling a method from a super class

Hello, I'm trying to write a program that will call a method from a super class. This program is the test program, so should i include extends in the class declaration? Also, what code is needed for the call? Just to make things clear the program includes three different types of object classes and one abstract superclass and the test program which is what im having problems with. I try to use the test program to calculate somthing for each of them using the abstract method in the superclass, but its overridden for each of the three object classes. Now to call this function what syntax should I include? the function returns a double. Thanks.

Well, this sort of depends on how the methods are overridden.
public class SuperFoo {
public void foo() {
     //do something;
public void bar(){
     //do something
public class SubFoo extends SuperFoo {
   public void foo() {
      //do something different that overrides foo()
   public void baz() {
      bar(); //calls superclass method
      foo(); //calls method in this (sub) class
      super.foo(); //calls method in superclass
}However, if you have a superclass with an abstract method, then all the subclasses implement that same method with a relevant implementation. Since the parent method is abstract, you can't make a call to it (it contains no implementation, right?).

Weird one.. i can't return a variable from the extended to the super class

Hey everyone, i hope i'm not annoying you guys :)
So today's problem is to return a variable (int) from a method of the extended class and print it ont the super class.
I'm just testing the super class , if it works fine.
So the extended class ( FileIO) just read the file txt and return the integer or string ( from the txt file)
I already did a main method to that class and tested it, it works fine.
So now the problem is to print the integer ( that the extended class gets from the txt. ) inside the Super class. I mean , is the same thing but now im testing the Super class , just have to do the same thing, a super class method calls the extended class method and receive the integer from the txt file.
i think the problem is when i create the instance of the FileIO object , maybe its constructor ...i don't know.
The name of the txt file is passed from the super class to the extended class, but i think the error is not from there.
this.aero_le = new BufferedReader(new FileReader(super.ficheiroleitura_aero())); // super calls ficheiroleitura_aero() and receive the name of the txt file ( e.g "temp.txt") so i think that is correct.
here's the code of the Super class public class Aeroporto {
     private String filereader_voo = "temporary.txt";
     private String filereader_aero = "temp.txt";
     private String siglaAero = "";
     public FileIO file;
     public Aeroporto(){};
     public Aeroporto(String filereader_voo, String filereader_aero) throws IOException{
          this.filereader_voo = filereader_voo;
          this.filereader_aero =filereader_aero;
          file = new FileIO();
     public String siglaAero() {
          return siglaAero; }
     public String filereader_aero(){
          return filereader_aero;
public int nrLines() throws IOException{   // it was supose to retunr the number of lines ( integer) from the txt file .
          return Integer.parseInt(file.lerLinhaN(1,1));
// main() {
Aeroporto a = new Aeroporto();
          int v = a.nrLines();
          System.out.print(v);
// ***********************************************************+
// Extended Class
public class FileIO extends Aeroporto{
     private String ficheiroescrita;
     private PrintWriter vooescreve, aeroescreve ;
     private BufferedReader voo_le, aero_read;
     public FileIO(){}
     public FileIO(String filereader_voo, String filereader_aero, String ficheiroescrita) throws IOException {
          super(filereader_voo, filereader_aero);
          this.ficheiroescrita = ficheiroescrita;
          //If file does not exists , create one.
          try{
               this.aero_read = new BufferedReader(new FileReader(super.filereader_aero()));
               aero_read.close();
          catch(IOException ex){
               this.aeroescreve = new PrintWriter(new FileWriter(ficheiroescrita));
               aeroescreve.close();
public String lerLinhaN(int line, int column) throws IOException{ // this method works fine , i already tested this class.
          this.aero_read = new BufferedReader(new FileReader(super.filereader_aero()));
          for(int i = 0; i != line-1; ++i) aero_read.readLine();
          String linha = aero_read.readLine();
          String [] words = linha.split(" ");
          return words[column-1];
Maybe the error is that i use to test the Super class a default contructor on both classes... i don't know where the error is, i also did two small classes ( super and another that extends ) and get the string "Hello" from the super and print it inside the extended..and it works, that's why i think the error is when i call the extended class .. need help.
thanks.

Ok,
This one might actually work... atleast it compiles.import java.io.BufferedReader;
import java.io.FileReader;
import java.io.File;
import java.io.PrintWriter;
import java.io.FileWriter;
import java.io.IOException;
public abstract class FileIO {
     public static boolean CreateOutputFileIfNotExists(
          String outputFilename //the name of the file to ensure exists.
     ) throws IOException
          final String functionName = "FileIO.CreateOutputFileIfNotExists";
          boolean retVal = false;
          //If the output file does does not exist then create it.
          //post condition: output file exists or an IOException has been thrown.
          BufferedReader infile = null;
          try{
               infile = new BufferedReader(new FileReader(outputFilename));
               retVal = true;
          } catch(IOException ex) {
               PrintWriter outfile = null;
               try {
                    outfile = new PrintWriter(new FileWriter(outputFilename));
                    retVal = true;
               } catch(IOException ex2){
                    throw new IOException(functionName + ": cannot create output file " + outputFilename, ex2);
               } finally {
                    outfile.close();
                    if (outfile.checkError()) {
                         throw new IOException(functionName + ": error on output stream " + outputFilename);
          } finally {
               try {
                    infile.close();
               } catch(IOException ex){
                    throw new IOException(functionName + ": cannot close output file " + outputFilename, ex);
          return(retVal);
     public static String readLine(
               String inputFilename //the name of the file to read.
          , int     lineNumber    //1 based number of the line to read from.
     ) throws IOException
          final String functionName = "FileIO.readLine";
          String outputLine = null;
          // reads the numbered "lineNumber" from "inputFilename".
          BufferedReader infile = null;
          try {
               infile = new BufferedReader(new FileReader(new File(inputFilename)));
               for(int i=1; i<lineNumber; ++i) infile.readLine();
               outputLine = infile.readLine();
          } catch(IOException ex){
               throw new IOException(functionName + ": cannot read input file " + inputFilename, ex);
          } finally {
               try {
                    infile.close();
               } catch(IOException ex){
                    throw new IOException(functionName + ": cannot close input file " + inputFilename, ex);
          return(outputLine);
     public static String readWord(
               String inputFilename //the name of the file to read.
          , int lineNumber        //1 based number of the line to read from.
          , int wordNumber        //0 based number of the word to read.
     ) throws IOException
          final String functionName = "FileIO.readWord";
          String outputWord = null;
          // reads the numbered space-seperated "wordNumber" from the numbered "lineNumber" of "inputFilename"
          try {
               String[] words = FileIO.readLine(inputFilename, lineNumber).split(" ");
               if (wordNumber>0 && wordNumber<words.length) outputWord = words[wordNumber-1];
          } catch(IOException ex){
               throw new IOException(functionName + ": cannot read input file " + inputFilename, ex);
          return(outputWord);
}Design notes... FileIO is a generic helper class... there is nothing specific to Airports, flights, or any other "domain" specific stuff in it... so it's re-usable... you can keep it and reuse it on other projects, or even share it with your friends.
So... The airport class will just call the static methods on FileIO like this    ....
    int lineNumber=1;
    int wordNumber=1;
    String airportCode = FileIO.readWord(airportsFilename, lineNumber, wordNumber);
    ....How's that?
corlettk: my now mandatory edit.

How to get the subclass from a super class( or interface)

hi,
I want to get subclass from a super class (or a interface), how to do that? the subclass of a interface means the class implementing the interface.
for example;
List ls;
I want to get the subclass of ls, i.e., LinkedList, Stack, Vector......
AbstractList al;
the subclass of al, i.e., ArrayList, Vector.......
thanks
Aiwu

List ls = new ArrayList();Since ls has been declared as a List we can only use List methods
with it. This is a good thing because we might later want to change
it to some other sort of List.
I want to get subclass from a super class (or a interface), how to do
that?The instance of the subclass declared above did not really come
from the super class. A class "knows nothing" about its
subclasses: many sub classes would not even exist at the time
the class was written.

Calling a particular Method of all subclass from a super class

hi
I have a class 'A' which is a super class for 'B' ,'C' , 'D'
my main method is in the class Main and while on the run i am calling methods of B,C,D form this main class.
but as the first step of execution i need to call a init method which has been defined in all the sub-classes. and there can be any no of sub-classes and all will have the init method and i have to call the init method for all classes. is this possible to do that in runtime. ie i wil not be knowing the names of sub-classes.
thanks
zeta

Sorry if i had mislead you all.
I am not instantiating from my super class.
as mjparme i wanted one controller class to do the
init method calls
so i got it working from the link you gave.
URL url = Launcher.class.getResource(name);
File directory = new File(url.getFile());
This way i can get all the classes in that
in that package
and from reflection i can get whether it is
her it is a sub class of the particular super class
and i can call the init methods by making the init
methods static
thanks for the help
zetaThis is a rather fragile solution.
If the problem is one of knowing which subclasses exist, I would suggest specifying them explicitly via configuration (system property or properties file or whatever).
One thing that's not entirely clear to me: Is the init going to be called once for each subclass, or once for each instance of each subclass? It sounds to me like it's once per class, but I want to make sure.

Inherit protected attribute from a Super class

Hi All,
I am inheriting a standard class which has many instance protected attributes. how do i access the super classes protected attributes from the sub class. i.e i need the value present in the super class attribute to be used in a sub class method.
will i be able to get the value of an instance attribute??
Thanks in advance,
Arun.

Hi marc,
I was also wondering as to how we can make use of the public attributes in the sub classes.as in, what the syntax we need to follow.
It'd be great if you could give a simple example with one protecetd attribute accessed in the subclass.
I've written a sample prog.
REPORT YA_TEST_OO.
      CLASS s_abc DEFINITION
CLASS s_abc DEFINITION.
PRIVATE SECTION.
    DATA: d_abc TYPE i.
ENDCLASS.                    "s_abc DEFINITION
      CLASS sb_abc DEFINITION
CLASS sb_abc DEFINITION INHERITING FROM s_abc.
public SECTION.
DATA: sb_d_abc TYPE c." VALUE d_abc.
    METHODS: m_abc.
ENDCLASS.                    "sb_abc DEFINITION
      CLASS sb_abc IMPLEMENTATION
CLASS sb_abc IMPLEMENTATION.
METHOD m_abc.
   sb_d_abc = d_abc + 1.
ENDMETHOD.                    "m_abc
ENDCLASS.                    "sb_abc IMPLEMENTATION
It doesn't work though.
Thanx,
Zid.

My name is Mike. I live in New Zealand. My username is waipukurau1. I downloaded MacBook booster from the prompts. Was this a good idea and good for my MacBook Pro? Please answer.

My name is Mike. I live in New Zealand. My username is waipukurau1. I downloaded MacBook booster. I write to ask was this a good idea? Was this good and correct for my MacBook Pro. Please answer.

ashish35,
No one from Apple here - we're just users like you. All I can tell you is that electronic fail and with MacBook Pros (and most notebooks) the components are so integrated as to make a repair to the logic board practically impossible, hence the high prices charged for repairs.
Only you can decide if you want to have your computer repaired or put the money towards the purchase of a new computer. If you do decide to purchase a new unit I would suggest that you also purchase the AppleCare Protection Plan which increases your warranty from one year to three years.
Sorry and good luck,
Clinton

Overwriting a method of a super class in the subclass ???

Hi,
can somebody tell me whether it's possible to add a new implementation of a method in the sub class which is inherited from a super class?
I want to model my program in that way:
1. I define a super class with some implemented methods.
2. This class should be inherited in a sub class. One method should be used as it was implemented in the super class but another method should be overwritten in the subclass.
I know this concept from Java but I couldn't find a way how to do it in ABAP
Many thanks for any help!
Best regards,
Birgit

hi,
yeas you can do it,
Subclass can re-implement the inherited public and protected methods from superclass.Class C1 contains method METH1(public) and METH2(protected), both of which are modified and re-implemented in its subclass C2.also you can have ur own methods in subclass.Objects are created out of both classes and the method METH1 for both objects are called.
Output of the program demonstrates different behaviour for method METH1 of class C1 and C2.
This demonstrates the theme.
REPORT YSUBDEL.
CLASS C1 DEFINITION.
PUBLIC SECTION.
   METHODS : METH1.
PROTECTED SECTION.
   METHODS METH2.
ENDCLASS.
CLASS C1 IMPLEMENTATION .
METHOD : METH1.
   WRITE:/5 'I am meth1 in class C1'.
   CALL METHOD METH2.
ENDMETHOD.
METHOD : METH2.
   WRITE:/5 ' I am meth2 in class C1 '.
ENDMETHOD.
ENDCLASS.
CLASS C2 DEFINITION INHERITING FROM C1.
PUBLIC SECTION.
METHODS : METH1 redefinition,
meth3.
PROTECTED SECTION.
METHODS : METH2 redefinition.
ENDCLASS.
CLASS C2 IMPLEMENTATION.
METHOD METH1.
   WRITE:/5 'I am meth1 in class C2'.
   call method meth2.
endmethod.
METHOD : METH2.
WRITE:/5 ' I am meth2 in class C2 '.
ENDMETHOD.
METHOD : METH3.
WRITE:/5 ' I am own method of class C2'.
ENDMETHOD.
endclass.
START-OF-SELECTION.
DATA : OREF1 TYPE REF TO C1 ,
         OREF2 TYPE REF TO C2.
CREATE OBJECT : OREF1 , OREF2.
CALL METHOD : OREF1->METH1 ,
                OREF2->METH1.
hope it helps,
regards

Inherited methods of super class not shown in outline

Hello, is there a possibility to display the methods and variables from the super class in the outline of the inheriting class in AiE?

Hi Christian,
We had discussed this, when we implemented the outline and quick outline some years, ago. Finally, we sticked to the approach that is used by other plug-ins in Eclipse (like JDT).
There Outline View shows only the content of the current editor. This helps to keep the content of the view stable when you select an element for navigation (because you won't be able to switch the editor by selecting an element ).
Inherited members are usually part of other editors, unless you have redefined a method in your current class. Therefore, they are not shown in Outline View (unless they are redefinitions).
The filters like "Hide Non-Public Members of classes" can only hide elements of the current editor.
Inherited members can be shown in the Quick Outline, because the interaction pattern is different there: If you navigate to an element the pop-up is closed. Therefore, a content change of the Quick-Outline does not hurt.
Michael

ER: Java class diagrams do show inheritance from no-sourcecode classes

Hi!
We just noticed that when we extend some classes for which the source code is not available, such inheritance is not visible on diagrams.
I would like to propose ER to show these inheritances (as the no-source classes signatures are enough to display the class on diagram). It is very inconvenient to have diagrams without possibility to depict the inheritance from many Oracle classes, as this inheritance is more and more important for building ADF applications.
Thanks for consideration.
PaKo

Pako,
I filed the ER
Frank

Invoking a WLI 9.2 business process from JSF Controller class

I want to call a WLI business process from a java class, which will run in the same JVM as the WLI. I have read that JPD Proxy can be used for this purpose. I am concerned with the overhead of RMI calls. Any insight into this would be helpful .

Hi Raj
You have to use JPDproxy to call a business process from a java class. This is what BEA also recommends at http://e-docs.bea.com/workshop/docs81/doc/en/integration/howdoI/howProxyJavaClient.html as this is the only way to call a JPD from plain java class.
Many customers use this and even if there is, the overhead should not be substantial.
You may also want to try posting in the WLI newsgroup at http://forums.bea.com/bea/forum.jspa?forumID=2047
Vimala-

Add OrganizationalGroup from a Java Class

Hi,
I want to add a new Organizational Group with two roles.
How could I do it from a java class?
This is the code to add a role, but to add a Group with two roles??
DirOrganizationalRole organizationalRole = null;
organizationalRole = DirOrganizationalRole.create(directorySession, "Nombre del Rol", false, "Desc. del Rol");
Thanks in advance!!

This is the JAVA code to add a role:
DirOrganizationalRole organizationalRole = null;
organizationalRole = DirOrganizationalRole.create(directorySession, "Nombre del Rol", false, "Desc. del Rol");
And this to verify if the role exist:
DirOrganizationalRole organizationalRole = null;
organizationalRole = DirOrganizationalRole.fetch(directorySession, rol);
I have tried to do this with a DirOrganizationalGroup but I can't....
Exist any documentation about this classes?
Could anybody write a simple code example?
I think it's very easy....
DirOrganizationalGroup organizationalGroup = null;
organizationalGroup = DirOrganizationalGroup.create(directorySessionRol, "DirSubdir", "Grupo Directores y Subdirectores", null, null, true, true);
And the RoleAssigment??
Thanks!!

Trying to use super class's methods from an anonymous inner class

Hi all,
I have one class with some methods, and a second class which inherits from the first. The second class contains a method which starts up a thread, which is an anonymous inner class. Inside this inner class, I want to call a method from my first class. How can I do this?
If I just call the method, it will use the second class's version of the method. However, if I use "super," it will try to find that method in the Thread class (it's own super class) and complain.
Any suggestions?
Code:
public class TopClass
     public void doSomething(){
          // do something
=============================
public class LowerClass extends TopClass
     // overrides TopClass's doSomething.
     public void doSomething(){
          // do something
     public void testThread(){
          Thread t = new Thread(){
               public void run(){
                    doSomething();               //fine
                    super.doSomething();          //WRONG: searches class Thread for doSomething...
          t.start();
}

Classes frequently call the un-overridden versions of methods from their superclasses. That's that the super keyword is for, if I'm not mistaken.You're not mistaken about the keyword, but you're not calling the superclass method from a subclass. Your anonymous inner class is not a subtype of TopLevel. It's a subtype of Thread.
Here it is no different, except that I happen to be in a thread at the time.It's vastly different, since you're attempting to call the method from an unrelated class; i.e., Thread.
I could also be in a button's action listener, for example. It seems natural to me that if I can do it in a method, I should be able to do it within an anonymous inner class which is inside a method.If you were in an button's action listener and needed to call a superclass' implementation of a method overridden in the button, I'd have the same questions about your design. It seems smelly to me.
~

How to get private fields from super class?

Hi.
I must get protected and private fields from a class. I know that sounds werid but I have a very good reason for doing so, ask if you want.
I have tried the getDeclaredField(String) method, but it apparently doesn't return the fields declared by the super classes.
What's the smartest solution to this?
Thank you all.
edit: note that the superclass hierarchy's length is 3 and that there are several classes at the bottom level.
Edited by: bestam on Sep 24, 2009 2:05 PM

bestam wrote:
I do not claim I have invented a new programming language Sir, you must be mistaken. This is not turing complete.
This is a language for describing Cards or a game's rules if you want.
AspectJ isn't Turing complete but AspectJ is still a compiler.
This is how I have been working :
- I have implemented the core library in Java (what is a Player, what is an Effect, what is a Card, what is a BuildingCard, what is a Player's Turn and so on)
- It also includes packages dedicated to service, able to retrieve and send data to the clients via sockets.
- Then I have "hardcoded" a dozen of specific cards in Java, for testing and validating the core library. I have been doing so by extending the BuildinCard's class for example.
- But my ultimate goal is not to code thoses 1.000+ cards of the game in Java. I chosed to design a little language so that I would end up writing cards faster. While I'm traversing the syntactical tree representing the card, I feed the card's fields one by one. Some of them are quite primitive, some other are more complex and have a recursive nature for instance.
Providing detail for how you implemented it doesn't change anything about what I already said.
Thus, this is not really a compiler as it doesn't transform a text in language A into a text in language B.
You really need to understand more about what "compilers" and certainly compiler theory do before you decide what they can and cannot do.
And your statement still does not change what I said.
Is this wrose than the bean design pattern from JSP ? I'm not sure.
Bean design? A "bean" has almost zero requirements.
Aside of that, it's a bit harsh to be told "read the fucking manual" while I have written my first compiler some years ago.Not sure who that was directed. I suggested some reading material on compiler theory.
If you think that your idea is ideal then knock yourself out. Since I doubt I will end up seeing it in anything that I must maintain it doesn't matter to me. But you did in fact ask what the best solution was.

Loading external swfs extending from classes in the same shared codebase

Hey there!
I'm currently developing a game in flash and want to be able to divide up my .fla assets in a way that means artists can work on a game menu .fla in isolation from the game.fla and rest of the game code.
If I could briefly explain how I've approached this so far, I would be extremely if people could shout in my general direction and tell me I am stupid, or even better still, give me helpful advice as to where I am going wrong and how I can correct it!
My project is setup like this:
HighScoreMenu.fla -> document class HighScoreMenu extending GameMenu class.
game.fla ->document class game.as
game.as class loads the published HighScoreMenu.swf and manipulates the menu i.e. animates on and off screen via inherited functions in the GameMenu class.
Now this seemed to work to begin with, until my code evolved and upon going to publish my HighScoreMenu.fla flash started complaining about symbols being used in Game.as that were in Game.fla... If I'm only publishing the HighScoreMenu which extends from GameMenu then why is it even looking to compile Game.as?
Can you spot the problem in the way I am doing this, or is there a better approach I should try?
Any advice greatly appreciated!
Stevie.

No it doesn't seem to, however though they both have a reference to the HighScoreManager so there is some overlap there between menu and game code, but the menu classes don't reference any symbols on the game.fla...
Just to clarify, I have an fla HighScoreMenu.fla, which has a child symbol HighScoreMenu which uses the following class.
public dynamic class HighScoreMenu extends GameMenu
//convenient storage for competition Manager object
private var _highScoreManager:HighScoreManager;
The game then loads this class as follows:
I load the swf "HighScoreMenu.swf" and once its loaded I obtain the menu class like so:
var cls:Class = Class( applicationDomain.getDefinition("Menus.HighScoreMenu") );
var object:* = new cls();
...and create a new instance of the menu.
Is there anything fundamentally wrong with approaching it in this way?

If a dto extends from a super class is this a good design ?

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