Assigning a super class attributes to a sub class

I get handed an object of type Car, and wish to create a new object of type Ferari which is simply an extension of a type Car class object. How can I best do this? Normally I start with the extended type of object and 'fill' that objects attributes, but on this occasion, I receive a simpler object and wish to create a specialised object based on it.
The problem it seems is that assigning just the base object doesn't seem to do it (all fields are null).
// Car
public class Car {
  private int engineSize;
  // More code here
// Ferari
public class Ferrari extends Car {
  private int turboChargers;
      * Constructor
     public Ferrari(Car car) {
// This doesn't seem to work
//     this = (Ferrari) car;            
     // Hmmm.  Tiresome and error-prone assignments
     setEngineSize(car.getEngineSize());
     setColor(car.getColor());
       // etc.
}     Thanks for any suggestions!

Wait - sorry, it's more like a copy constructor. I missed that the first time through.
There's no good way around it - you'll have to get those values in there somehow. Unless there's a reasonable default value for all the Ferrari members that aren't part of Car, you'll have a problem with this because of the slicing problem.
It's as if you're writing a C++ copy constructor. It's just an alternative to the Java clone method.
If there are really that many attributes, maybe you can assign them using the Java reflection API.
Unless there are hundreds of them, type them once and be done with it. If there ARE hundreds of them, you might want to consider refactoring your class. It's too big!
You'll have to do that kind of thing when you write the equals and hashCode methods for your classes. Just do it! - MOD

Similar Messages

  • Assigning a super class attributes to a sub class in an OO way

    I think you OO and Pattern forumites might want to help me out on this one.
    I started this in the beginners forum, much heat, but not too much light
    http://forum.java.sun.com/thread.jsp?forum=54&thread=439107
    Make sure you at least read past peoples initial misunderstanding of the problem!
    I get handed an object of type Car, and wish to create a new object of type Ferari which is simply an extension of a type Car class object. How can I best do this? Normally I start with the extended type of object and 'fill' that objects attributes, but on this occasion, I receive a simpler object and wish to create a specialised object based on it.
    The problem it seems is that assigning just the base object doesn't seem to do it (all fields are null).
    // Carpublic class Car {  private int engineSize;  // More code here}// Feraripublic class Ferrari extends Car {  private int turboChargers;          /**      * Constructor      */     public Ferrari(Car car) {// This doesn't seem to work//     this = (Ferrari) car;                 // Hmmm.  Tiresome and error-prone assignments     setEngineSize(car.getEngineSize());     setColor(car.getColor());          // etc.        }}

    sure, but the decorator would still BE a JFrame (or
    more likely a container)No, in the examples I have seen the Decorator is outside the heirarchy.
    Given your many useful posts, I highly doubt that
    you're missing a key point in understanding the
    decorator pattern.I have to admit that I am not as strong on patterns as I should be. I tend to learn things as I need them. The problem is often you don't realize you need patterns until you learn about them.
    MY opinion is that there can be no hard, strict
    definition of any pattern; as they are (in Fowler's
    words) "half-baked", and require modification to be
    implemented in any specific problem.I'll by that.
    Is my code a decorator? Yes, in my opinion. I also
    think its a delegate (though many would dispute that
    saying the delegatee "must" have a reference to the
    delegator to be a "true" delegate pattern).I've always called this Composition or a Wrapper. The link I found that agreed with your example actually said that Wrappers and Decorators are synonymous. To me, these seem like very different approaches. That's why I am wondering if my understanding of the Decorator pattern is incomplete or too narrow.
    Could you please point me to those references?I think these are two. If you find something that shows your example fits these definitions please let me know.
    http://web.media.mit.edu/~tpminka/patterns/Decorator.html
    http://www.wikipedia.org/wiki/Decorator_pattern

  • Assigning the base class

    I have a bunch of DefaultMutableTreeNodes already created and I
    want to convert them all to myTreeNode objects which extends
    DefaultMutableTreeNode. Is there an easy way for assigning the super class of myClass which is DefaultMutableTreeNode.
    I know this doesn't work but what I want to do is something like
    setting the super class= passed in DMTN.
    I know I could create the original node1,node2 as myTreeNodes instead but these nodes are created in a bunch of different places and I would prefer not having to modify that code.
    node1 = new DefaultMutableTreeNode();
    node2 = new DefaultMutableTreeNode();
    new myTreeNode(node1);
    class myTreeNode extends DefaultMutableTreeNode{
    boolean isSelected;
    public myTreeNode(DefaultMutable TreeNode node){
    super = node.clone(); }
    }

    So you're saying you have this code:
    node1 = new DefaultMutableTreeNode();but you want to arrange things so that when it runs, it actually creates an object of some subclass of DMTN?
    No can do. While you're changing all the instances of that code, think about refactoring your application so that you don't have so many instances of it.

  • Can we change the Super class attribute scope in Sub class

    Hi.
    I created a super class. In that i have 4 attributes. That attributes are PUBLIC.
    I created a sub class. In that i got all super class attributes. I want to change that attributes as a Private. Is it possible.
    If it is possible.Give me an Example with code or Pseudo code.
    Regards.
    Krishna.

    Hi Krishna,
    It is not possible... If you declare the Attributes again in Subclass of the same name as that of Super class
    then the way of accessing them would be different from that of attributes in the main class.
    Hope this would help you
    Good luck
    Narin

  • Trouble assigning sub class to super class array

    Hi,
    I would greatly appreciate some help with the following:
    I want to assign a sub class to a super class array but the following code does not work
    where the board is comprised of the super class
         private static void makeMove( int X, int Y, int moveX, int moveY )
              ChessPiece tempChessPiece = ( ChessPiece ) board[ X ] [ Y ];
              board[ X ] [ Y ].setType( UNDEFINED );
              board[ moveX ] [  moveY  ] = tempChessPiece;
         }

    I have got this code to work but it does not appear
    to be very efficient to me as i dont recycle the
    objects.
    Any thoughts?The objects will be recycled by the garbage collector. It's very efficient so there's very little performance penalty in creating objects and releasing objects.
    Still, another alternative is to represent an empty square with null. In that case the code becomes,
    private static void makeMove( int selectedX, int selectedY, int moveToX, int moveToY ) {
       board[moveToY][moveToX] = board[selectedX][selectedY]; // piece to new position
       board[selectedX][selectedY] = null; // remove from old
    }I don't know your exact design but that should work. It's kind of natural too. If a square is empty there's no piece object there at all. No new object has to be created and that explicit cast is gone.

  • Instantiation of similar object over a super class deciding the sub class

    Hello all
    First, sorry if I'm duplicating an already answered question. I didn't searched very deep.
    Initial position:
    I have 2 Object (A1 and A2) which share the most (about 90%) of their instance variables an the associated methods. The values of the instance variables are retrieved in the real implementation from a stream. Depending of the data of the stream, I have to instantiate either a A1 or A2 object.
    A test implementation (using an int in case of the stream):
    The super class A:
    package aaa;
    public class A
      protected int version = -1;
      protected String name = null;
      protected AE ae = null;
      protected A()
      protected A(int v)
        // Pseudo code
        if (v > 7)
          return;
        if (v % 2 == 1)
          this.version = 1;
        else
          this.version = 2;
      public final int getVersion()
        return this.version;
      public final String getName()
        return this.name;
      public final AE getAE()
        return this.ae;
    }The first sub class A1:
    package aaa;
    public final class A1 extends A
      protected A1(int v)
        this.version = v;
        this.name = "A" + v;
        this.ae = new AE(v);
    }The second subclass A2:
    package aaa;
    import java.util.Date;
    public final class A2 extends A
      private long time = -1;
      protected A2(int v)
        this.version = v;
        this.name = "A" + v;
        this.time = new Date().getTime();
        this.ae = new AE(v);
      public final long getTime()
        return this.time;
    }Another class AE:
    package aaa;
    public class AE
      protected int type = -1;
      protected AE(int v)
        // Pseudo code
        if (v % 2 == 1)
          this.type = 0;
        else
          this.type = 3;
      public final int getType()
        return this.type;
    }To get a specific object, I use this class:
    package aaa;
    public final class AFactory
      public AFactory()
      public final Object createA(int p)
        A a = new A(p);
        int v = a.getVersion();
        switch (v)
        case 1:
          return new A1(v);
        case 2:
          return new A2(v);
        default:
          return null;
    }And at least, a class using this objects:
    import aaa.*;
    public final class R
      public static void main(String[] args)
        AFactory f = new AFactory();
        Object o = null;
        for (int i = 0; i < 10; i++)
          System.out.println("===== Current Number is " + i + " =====");
          o = f.createA(i);
          if (o instanceof aaa.A)
            A a = (A) o;
            System.out.println("Class   : " + a.getClass().getName());
            System.out.println("Version : " + a.getVersion());
            System.out.println("Name    : " + a.getName());
            System.out.println("AE-Type : " + a.getAE().getType());
          if (o instanceof aaa.A2)
            A2 a = (A2) o;
            System.out.println("Time    : " + a.getTime());
          System.out.println();
    Questions:
    What would be a better way to encapsulate the logic into their respective objects ? Is there a way to let the super class A itself identify the type of the object and then extend from A to either A1 or A2 ?
    Thanks in advance
    Andreas

    Hello jduprez
    First, I would thank you very much for taking the time reviewing my problem.
    Just for the record: have you considered regular serialization? If you control the software at both ends of the stream, you could rely on standard serialization mechanism to marshall the objects and unmarshall them automatically.In my case, I can't control the other site of the stream. At the end, the data comes from a FileInputStream and there aren't objects on the other site, only pur binary data.
    - It seems you have one such factory class. Then you already have encapsulated the "determine class" logic, you don't need to add such logic in superclass A.I thought from an OO view, that the super class A is responsible of doing that, but that's where the problem starts. So at the end, it's better doing it in the factory class.
    - A itself encapsulates the logic to load its own values from the stream.
    - A1 and A2 can encapsulate the logic to load their own specific value from a stream (after the superclass' code has loaded the superclass' attributes values).
    My advise would be along the lines of:
    public class A {
    .... // member variables
    public void load(InputStream is) {
    ... // assign values to A's member variables
    // from what is read from the stream.
    public class A1 extends A {
    ... // A1-specific member variables
    public void load(InputStream is) {
    super.load(is);
    // now read A1-specific values
    public class AFactory {
    public A createA(InputStream is) {
    A instance;
    switch (is.readFirstByte()) {
    case A1_ID:
    a = new A1();
    break;
    case A2_ID:
    a = new A2();
    break;
    a.load(is);
    }The example above assumes you have control over the layout of the data in the stream (here for a given A instance, the attributes defined in A are read first, then come the subclass-specific attributes.
    The outcome is: you don't have to create a new A( ) to later create another instance, of a subclass.I like the idea. In the AFactory, is the "A instance;" read as "A a;" ?
    Is there a way to let the super class A itself identify the type of the object and then extend from A to either A1 or A2 ?Note I initially read this question as "can an instance of a class mutate into another class", to which the answer is no (an object has one single, immutable class; it is an instance of this class, and of any superclass and superinterface, but won't change its class at runtime).Yes, I have been thinking about a way for mutating into a subclass to keep the already initialized values from the A class without copying or parsing again. But preventing an instance of an A class will be my way. So, in this aspect, Java didn't changed in the last 10 years... It's a long time ago I've used Java for some real projects.
    You can, however, create an instance of another class, that copies the values off a priori A instance. Your example code was one way, another way could be to have a "copy constructor":
    public class A {
    public A(A model) {
    this.att1 = model.att1;
    this.att2 = model.att2;
    public class A1 {
    public A1(A model) {
    super(model);
    ... // do whatever A1-specific business
    )Still, I prefer my former solution less disturbing: I find the temporary A instance redundant and awkward.Nice to know. I prefer the first solution too.
    Thank you again for the help and advices. My mind is searching sometimes for strange solutions, where the real is so close ;-)
    Andreas

  • 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.

  • Can we chagne Super class method parameters in Sub class

    Hi,
    I created a super class.  In that class i created a method. That method is having 4 input parameters and 4 export parameters.
    I created a sub class for that super class. I need to use only 2 input parameters in this class rather than 4 parameters. I want to delete 2 Input parameters in the sub class of the super class method.  Is it possible.
    If possible. can we give an simple code or pseudo code?
    regards,
    krishna

    Hi,
    I think you can not.
    Because, only public attributes can be inherited and they will remain public in the subclass.
    for further detail check,
    http://help.sap.com/saphelp_nw70/helpdata/en/1d/df5f57127111d3b9390000e8353423/content.htm
    regards,
    Anirban

  • Accessing a Sub class variable in a Super Class

    Hi ,
    Is there any easiest way to access a Subclass Variable in a Super Class.
    Class Super1{
    Class sub extends Super1
    private String substring1;
    In my application the 'substring1' values is not null .But all fields in Super1 class are null .
    How can i access the value of the Subclass Variable in Super class .
    Thanks

    This would be a way to make the superclass dependent on subclass behavior. Of course this only makes sense if getSubString() is likely to have multiple different implementations in different subclasses.
    public abstract class Super {
      public String getString() {
       return "SuperString" + getSubString();
      protected abstract String getSubString();
    public class Sub extends Super {
      private String substring;
      protected String getSubString() {
       return substring;
    }Using this just to access a variable whose contents differ from subclass to subclass is overkill. If you want each subclass to provide a different substring, create a constructor with a substring parameter in the superclass instead:public class Super {
      private String substring;
      protected Super(String substring) {
       this.substring = substring;
      public String getString() {
       return "SuperString" + substring;
    public class Sub extends Super {
      public Sub() {
       super("substring");
    }

  • Is it possible to OVERLOAD a super-class method in a sub-class?

    Hi all,
    I have a query that
    Is it possible to OVERLOAD a super-class method in a sub-class?
    If it is possible, please give me an example.
    Thanks,
    Hari

    Hi,
    Is the method int Display(int a){} overloading
    the super-class's void Display() method? If
    possible, please clarify this and how it would be
    method overloading?
    hanks,
    Hari
    Hi Hari,
    Yes, it is possible. Look at this piece of code:
    class Senior
         void Display()
              System.out.println("Super class method");
    class Junior extends Senior
         int Display(int a)
              System.out.println("Subclass method: "+a);
              return(a+10);
         }> }
    class example
         public static void main(String args[])
              Junior j = new Junior();
              j.Display();
    System.out.println("Subclass method
    od "+j.Display(5));
    Is this what you were asking? Hope this helped.Hi,
    I guess you guys are confused here...
    Overloading is achieved by methods in the same class...
    Overriding is across a superclass subclass methds.

  • How to inherit super class constructor in the sub class

    I have a class A and class B
    Class B extends Class A {
    // if i use super i can access the super classs variables and methods
    // But how to inherit super class constructor
    }

    You cannot inherit constructors. You need to define all the ones you need in the subclass. You can then call the corresponding superclass constructor. e.g
    public B() {
        super();
    public B(String name) {
        super(name);
    }

  • Can defualt inherited the Super Class constructor to sub class ?

    Hi,
    is it passible to inherit the super class constructor by defualt when extends the super class.
    Thanks
    MerlinRoshina

    Constructor rules:
    1) Every class has at least one ctor.
    1.1) If you do not define an explicit constructor for your class, the compiler provides a implicit constructor that takes no args and simply calls super().
    1.2) If you do define one or more explicit constructors, regardless of whether they take args, then the compiler no longer provides the implicit no-arg ctor. In this case, you must explicitly define a public MyClass() {...} if you want one.
    1.3) Constructors are not inherited.
    2) The first statement in the body of any ctor is either a call to a superclass ctor super(...) or a call to another ctor of this class this(...) 2.1) If you do not explicitly put a call to super(...) or this(...) as the first statement in a ctor that you define, then the compiler implicitly inserts a call to super's no-arg ctor super() as the first call. The implicitly called ctor is always super's no-arg ctor, regardless of whether the currently running ctor takes args.
    2.2) There is always exactly one call to either super(...) or this(...) in each constructor, and it is always the first call. You can't put in more than one, and if you put one in, the compiler's implicitly provided one is removed.

  • Error while calling a super class public method in the subclass constructor

    Hi ,
    I have code like this:
    CLASS gacl_applog DEFINITION ABSTRACT.
      PUBLIC SECTION.
        METHODS:
                create_new_a
                   IMPORTING  pf_obj       TYPE balobj_d
                              pf_subobj    TYPE balsubobj
                              pf_extnumber TYPE string
                   EXPORTING  pfx_log_hndl TYPE balloghndl
                   EXCEPTIONS error
    ENDCLASS.
    CLASS gacl_applog IMPLEMENTATION.
      METHOD create_new_a.
        DATA: ls_log TYPE bal_s_log.
      Header aufsetzen
        MOVE pf_extnumber TO ls_log-extnumber.
        ls_log-object     = pf_obj.
        ls_log-subobject  = pf_subobj.
        ls_log-aluser     = sy-uname.
        ls_log-alprog     = sy-repid.
        ls_log-aldate     = sy-datum.
        ls_log-altime     = sy-uzeit.
        ls_log-aldate_del = ls_log-aldate + 1.
        CALL FUNCTION 'BAL_LOG_CREATE'
             EXPORTING
                  i_s_log      = ls_log
             IMPORTING
                  e_log_handle = pfx_log_hndl
             EXCEPTIONS
                  OTHERS       = 1.
        IF ( sy-subrc NE 0 ).
          MESSAGE ID      sy-msgid TYPE sy-msgty NUMBER sy-msgno
                  WITH    sy-msgv1 sy-msgv2 sy-msgv3 sy-msgv4
                  RAISING error.
        ENDIF.
      ENDMETHOD.
    CLASS gcl_applog_temp DEFINITION INHERITING FROM gacl_applog.
      PUBLIC SECTION.
        DATA: log_hndl   TYPE balloghndl READ-ONLY
            , t_log_hndl TYPE bal_t_logh READ-ONLY
        METHODS: constructor
                   IMPORTING  pf_obj       TYPE balobj_d
                              pf_subobj    TYPE balsubobj
                              pf_extnumber TYPE string
                   EXCEPTIONS error
               , msg_add      REDEFINITION
               , display      REDEFINITION
    ENDCLASS.
    CLASS gcl_applog_temp IMPLEMENTATION.
      METHOD constructor.
        CALL METHOD create_new_a
               EXPORTING  pf_obj       = pf_obj
                          pf_subobj    = pf_subobj
                          pf_extnumber = pf_extnumber
               IMPORTING  pfx_log_hndl = log_hndl.
        IF ( sy-subrc NE 0 ).
          MESSAGE ID sy-msgid TYPE sy-msgty NUMBER sy-msgno
                  WITH sy-msgv1 sy-msgv2 sy-msgv3 sy-msgv4
                  RAISING error.
        ENDIF.
      ENDMETHOD.
    A public method of Super class has been called from the constructor of the sub class. we are getting the syntax error :
    ' In the constructor method, you can only access instance attributes, instance methods, or "ME" after calling the constructor of the superclass…'
    Can you please suggest how to change the code with out affecting the functioanlity.
    Thank you ,
    Lakshmi.

    Hi,
    Call that method by instance of Subclass.   OR
    SUPER-->method.
    Read very useful document
    Constructors
    Constructors are special methods that cannot be called using CALL METHOD. Instead, they are called automatically by the system to set the starting state of a new object or class. There are two types of constructors - instance constructors and static constructors. Constructors are methods with a predefined name. To use them, you must declare them explicitly in the class.
    The instance constructor of a class is the predefined instance method CONSTRUCTOR. You declare it in the public section as follows:
    METHODS CONSTRUCTOR
            IMPORTING.. [VALUE(]<ii>[)] TYPE type [OPTIONAL]..
            EXCEPTIONS.. <ei>.
    and implement it in the implementation section like any other method. The system calls the instance constructor once for each instance of the class, directly after the object has been created in the CREATE OBJECT statement. You can pass the input parameters of the instance constructor and handle its exceptions using the EXPORTING and EXCEPTIONS additions in the CREATE OBJECT statement.
    The static constructor of a class is the predefined static method CLASS_CONSTRUCTOR. You declare it in the public section as follows:
    CLASS-METHODS CLASS_CONSTRUCTOR.
    and implement it in the implementation section like any other method. The static constructor has no parameters. The system calls the static constructor once for each class, before the class is accessed for the first time. The static constructor cannot therefore access the components of its own class.
    Pls. reward if useful....

  • Regarding Super classes

    Hi,
    I have created one class in SE24. This class will be used as a super class for other classes.
    When subclasses are derived from this superclass, i want to make sure that some of the methods of superclasses are redefined by the subclasse compulsarily.
    So i want to force the subclasses to redefine complusarily some of the methods of its super class.
    Is this feasible. If so please let me know the corresponding approach.
    Thanks in advance !
    Pramod

    Hi,
    Check this out this will help you.
    Inheritance is the concept of passing the behavior of a class to another class.
    1.You can use an existing class to derive a new class.
    2.Derived class inherits the data and methods of a super class.
    3.However they can overwrite the methods existing methods and also add new once.
    4.Inheritance is to inherit the attributes and methods from a parent class.
    Inheritance:
    Inheritance is the process by which object of one class acquire the properties of another class.
    Advantage of this property is reusability.
    This means we can add additional features to an existing class with out modifying it.
    Go to SE38.
    Provide the program name.
    Provide the properties.
    Save it.
    Provide the logic for inheritance.
    *& Report  ZLOCALCLASS_VARIABLES                      *
    *&----------------------------------------------------*REPORT  ZLOCALCLASS_VARIABLES.
    *OOPS INHERITANCE
    *SUPER CLASS FUNCTIONALITY
    *DEFINE THE CLASS.
    CLASS CL_LC DEFINITION.
    PUBLIC SECTION.
    DATA: A TYPE I,
          B TYPE I,
          C TYPE I.
    METHODS: DISPLAY,
             MM1.
    CLASS-METHODS: MM2.
    ENDCLASS.
    *CLASS IMPLEMENTATION
    CLASS CL_LC IMPLEMENTATION.
    METHOD DISPLAY.
    WRITE:/ 'THIS IS SUPER CLASS' COLOR 7.
    ENDMETHOD.
    METHOD MM1.
    WRITE:/ 'THIS IS MM1 METHOD IN SUPER CLASS'.
    ENDMETHOD.
    METHOD MM2.
    WRITE:/ 'THIS IS THE STATIC METHOD' COLOR 2.
    WRITE:/ 'THIS IS MM2 METHOD IN SUPER CLASS' COLOR 2.
    ENDMETHOD.
    ENDCLASS.
    *SUB CLASS FUNCTIONALITY
    *CREATE THE CLASS.
    *INHERITING THE SUPER CLASS.
    CLASS CL_SUB DEFINITION INHERITING FROM CL_LC. "HOW WE CAN INHERIT
    PUBLIC SECTION.
    DATA: A1 TYPE I,
          B1 TYPE I,
          C1 TYPE I.
    METHODS: DISPLAY REDEFINITION,     "REDEFINE THE SUPER CLASS METHOD
             SUB.
    ENDCLASS.
    *CLASS IMPLEMENTATION.
    CLASS CL_SUB IMPLEMENTATION.
    METHOD DISPLAY.
    WRITE:/ 'THIS IS THE SUB CLASS OVERWRITE METHOD' COLOR 3.
    ENDMETHOD.
    METHOD SUB.
    WRITE:/ 'THIS IS THE SUB CLASS METHOD' COLOR 3.
    ENDMETHOD.
    ENDCLASS.
    *CREATE THE OBJECT FOR SUB CLASS.
    DATA: OBJ TYPE REF TO CL_SUB.
    START-OF-SELECTION.
    CREATE OBJECT OBJ.
    CALL METHOD OBJ->DISPLAY. "THIS IS SUB CLASS METHOD
    CALL METHOD OBJ->SUB.
    WRITE:/'THIS IS THE SUPER CLASS METHODS CALLED BY THE SUB CLASS OBJECT'COLOR 5.
    SKIP 1.
    CALL METHOD OBJ->MM1.     "THIS IS SUPER CLASS METHOD
    CALL METHOD OBJ->MM2.
    *CREATE THE OBJECT FOR SUPER CLASS.
    DATA: OBJ1 TYPE REF TO CL_LC.
    START-OF-SELECTION.
    CREATE OBJECT OBJ1.
    SKIP 3.
    WRITE:/ 'WE CAN CALL ONLY SUPER CLASS METHODS BY USING SUPER CLASS OBJECT' COLOR 5.
    CALL METHOD OBJ1->DISPLAY. "THIS IS SUPER CLASS METHOD
    CALL METHOD OBJ1->MM1.
    CALL METHOD OBJ1->MM2.
    This example will help you to solve your problem.
    For more detailed information GOTO -> SAPTECHNICAL ->Tutorials -> Object Oriented Programming.
    Regards Madhu.
    Code Formatted by: Alvaro Tejada Galindo on Jan 7, 2009 12:13 PM

  • 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.

Maybe you are looking for