About classes and Inheritance

hi every one,
i want use class with object in data block and i want know how i can use inheritance with objects.
becouse i have interview in this two subjects, can any body support my.
thanks,,,,,,,

Hello,
Start Forms Builder, the press F1 to display the online help.
In the search tab, you can type "Class Property" or "Object Library" to find documentation on those topics:
About Property Classes A property class is a named object that contains a list of properties and their settings. Once you create a property class you can base other objects on it. An object based on a property class can inherit the setting of any property in the class that makes sense for that object. Property class inheritance is an instance of subclassing. Conceptually, you can consider a property class as a universal subclassing parent. There can be any number of properties in a property class, and the properties in a class can apply to different types of objects. For example, a property class might contain some properties that are common to all types of items, some that apply only to text items, and some that apply only to check boxes. When you base an object on a property class, you have complete control over which properties the object should inherit from the class, and which should be overridden locally. Property classes are separate objects, and, as such, can be copied between modules as needed. Perhaps more importantly, property classes can be subclassed in any number of modules.
or
Using the Object Library These topics contain information about using the Object Library in Oracle Forms: About the Object Library Removing an Object from the Object Library Creating a tab in the Object Library Deleting a Tab in the Object Library Saving an Object in the Object Library Opening an Object Library Module Displaying the Object Library Closing the Object Library Commenting Objects in the Object Library
Francois

Similar Messages

Learn about classes and perfom in abap

hallow
i wont to learn how to use classes and perform
in abap, any document will help
regards

I will send you the documents...
please give your mail address...
it's good to here about ABAP OOPS.
Regards,
Jayant
Please award if helpful

About Classes and Interfaces

How can we define the classes and interfaces in an interview can u give me any realtime example for this

How can we define the classes and interfaces in an
interviewThe easiest explanation probably is to say that an interface in Java is a special class, namely a totally abstract one, that has been given a separate name.
Classes and interfaces (because they're classes in disguise) both constitute types, meaning that variables can be declared of them. The difference is that a class can carry implementation whereas an interface cannot (because it's totally abstract).
Java has single inheritance of implementation which means the the inheritance of classes is restricted to exactly one while you can inherit as many interfaces you like.

Abstract classes and inheritance

I'm trying to do some simple inheritance but I'm a little stuck. Without giving too much away here's what I have (or am trying to have). I have an abstract "Test" class and a number of concrete classes that extend that abstract class. In my main method I have an array of Test objects. Each object in the array is a certain kind of "Test" and each one has its own way of doing most things but it doesn't make sense to have just a plain Test object because it is an abstraction. In my code I go through the array and execute a method, runTest(), for each Test in the array. However, my abstract Test class doesn't have a runTest() method b/c it will never get used and java complains. At runtime shouldn't java figure out, OK this is TestA, so go to TestA's runTest method (polymorphism?). What should I put in my runTest method in the abstract class? I know I can put anything there but what is standard?

JFactor2004 wrote:
... Each object in the array is a certain kind of "Test" and each one has its own way of doing most things but it doesn't make sense to have just a plain Test object because it is an abstraction. In my code I go through the array and execute a method, runTest(), for each Test in the array. However, my abstract Test class doesn't have a runTest() method b/c it will never get used and java complains. If you want to instantiate the Test class
you need to provide an implementation for the runTest() method,
something like/*type*/ runTest() { throw new UnsupportedOperationException(); }

Which of this is true about class and object?

(a) A class is made of objects
(b) A class is a collection of objects
(c) A class supplies or delivers objects to the rest of the application
(d) A class is used as a template to create objects
(e) An object inherits its variables and their values from its class
(f) An object inherits its variables and methods from its class
(g) An object inherits its variables and methods from its class and its superclasses
(h) The variables and methods of a class are defined in its objects
(i) The variables and methods of an object are defined in its class
(j) The variables, variable values and methods of an object are given in its class

(a) A class is made of objects - true
(b) A class is a collection of objects - true
(c) A class supplies or delivers objects to the rest of the application - true
(d) A class is used as a template to create objects - true
(e) An object inherits its variables and their values from its class - false
(f) An object inherits its variables and methods from its class - true
A class is a not collection of objects. A class not only contains objects
A class represents objects and others.

I don't know what's wrong with my code. it's about class and object.

* This is generic type of Person
package myManagement;
* @author roadorange
public class Person {
private String SS;
private String firstName;
private String lastName;
private String middleName;
private String phoneNumber;
private String address;
private String birthDay;
public void setSS (String SS) {
this.SS = SS;
public String getSS() {
return SS;
public void setFirstName (String firstName) {
this.firstName = firstName;
public String getFirstName() {
return firstName;
public void setLastName (String lastName) {
this.lastName = lastName;
public String getLastName() {
return firstName;
public void setMiddleName (String middleName) {
this.middleName = middleName;
public String getMiddleName() {
return middleName;
public void setPhoneNumber (String phoneNumber) {
this.phoneNumber = phoneNumber;
public String getPhoneNumber() {
return phoneNumber;
public void setAddress (String address) {
this.address = address;
public String getAddress() {
return address;
public void setBirthDay (String birthDay) {
this.birthDay = birthDay;
public String getBirthDay() {
return birthDay;
public void Person() {
SS = "1234567890";
this.firstName = "abc"; //test the keyword "this"
this.lastName = "xyz";
middleName = "na";
phoneNumber = "123456789";
address = "11-11 22st dreamcity ny 11111";
birthDay = "11-11-1980";
public void print() {
System.out.println("Display Database\n"
+ "Social Security Number: *********" + "\n"
+ "First Name: " + getFirstName() + "\n"
+ "Middle Name: " + getMiddleName() + "\n"
+ "Last Name: " + getLastName() + "\n"
+ "Phone Number: " + getPhoneNumber() + "\n"
+ "Address: " + getAddress() + "\n"
+ "getBirthDay: " + getBirthDay() );
package myManagement;
//this class is used to test other class or test other object
public class testClass extends Person{
public static void main(String[] args) {
Person obj1 = new Person();
obj1.print();
System.out.println(obj1.getFirstName()); //test the object
Result:
Display Database
Social Security Number: *********
First Name: null
Middle Name: null
Last Name: null
Phone Number: null
Address: null
getBirthDay: null
null
i don't know why it's all null. i assign something in the default constructor. it shouldn't be "null".
does anyone know why?

when you create 2 class using netbean editor, person.java and test.java
i never compile person.java.
when i finish typing these 2 class and i just right click test.java and run.
my question is do i need to compile person.java before i run test.java directly??
does Netbean compile it automatically when i run test.java first time?
i add another constructor Person constuctor with one parameter in Person.java and create 2nd object to test the 2nd constuctor and run.
All the codes work, so does the first default constructor. i don't why is that.
Then i removed what i added and restore back to where it didn't work before and test again. it works.
@_@. so weird.
problem solved. thank you
Edited by: roadorange on Feb 25, 2008 7:43 PM

Want to know more about class and class type and characters in batch determ

hi ,
i want to know abt class functionality and how it is related to batch mgt,means functions of class type , characters etc.
ok thanks

Hi ,
Find the Class and Class Type for Batch Determination.
Create Class for Batch Management
Use
In this step, you define two classes for use with batches. One class contains the characteristic LOBM_VFDAT: Expiration Date, and the other class with three characteristics:
LOBM_RL: Remaining shelf life for batch,
LOBM_LFDAT Batch determination delivery date, and
LOBM_VFDAT Expiration date, shelf life.
Procedure1.
Access the activity using one of the following navigation options:
Transaction Code: CL02SAP R/3 Role Menu     Installation ® Create Class for Batch Management
2.Choose Create and maintain the necessary master data manually. The relevant data can be found in the file:
Class     Class type     Description     Characteristic        Characteristic     Characteristic
023_001     023     Products with Expiration Date     LOBM_VFDAT
023_002     023     Search class with expiration date     LOBM_RLZ     LOBM_LFDAT     LOBM_VFDAT
Result
The materials are later assigned to class 023_001 in the material masters. 023_002 is used in the batch determination search strategies for SD and PP/PI.
Regards,
SAROSH

A question about class and interface? please help me!

the following is program:
interface A{
public class B implements A{
public static void main(String [] args){
A a = new B();
System.out.println(a.toString());
}i want to ask a question, the method toString() is not belong to interface A, why a can call method toString()? the interface call the method that isn't belong to, why? please help me...

because a.toString() call the method toString() of class Object because B implements A, but extends Object and in the class Object there is a method toString(). infact if you override the method toString() in class B, a.toString() call toString() in class B.
try this:
interface A {}
public class B implements A
public String toString()
    return "B";
public static void main(String [] args)
    A a = new B();
    System.out.println(a.toString());
}by gino

Generic classes and inheritance

I am in the midst of converting some database object code over to split the data from the database functionality, and I am coming into issues with generics.
I have three bean classes:
abstract public class Payment {
// common fields and their get/set methods
public final class AU_Payment
extends Payment {
// extra fields and their get/set methods
public final class US_Payment
extends Payment {
// extra fields and their get/set methods
}The code to write these classes to the database used to be in those classes, now I am moving them out to their own classes. I need to have a similar hierarchy so I can obtain an instance of the right class (through a factory) to write these objects to the database.
public interface PaymentDB<T extends Payment> {
public Result load(Connection conn, T payment, ResultInfo resultInfo) throws SQLException;
public Result loadAll(Connection conn, List<T> allPayments, ResultInfo resultInfo) throws SQLException;
}If I have the code for the AU_PaymentDB as the following, it won't compile:
public class AU_PaymentDB<AU_Payment> {
public Result load(Connection conn, AU_Payment payment, ResultInfo resultInfo) throws SQLException {
    return null;
public Result loadAll(Connection conn, List<AU_Payment> payment, ResultInfo resultInfo) throws SQLException {
    return null;
}the compiler complains that the class doesn't override the interface, and I need to recode it to the following to get it to compile:
public class AU_PaymentDB<AU_Payment> {
public Result load(Connection conn, Payment payment, ResultInfo resultInfo) throws SQLException {
    return null;
public Result loadAll(Connection conn, List payment, ResultInfo resultInfo) throws SQLException {
    return null;
load now takes just a Payment in it's signature list, and loadAll takes an untyped List.
This means I can actually call load() with a US_Payment and it works fine, which I don't want. Also, I cannot add an AU_Payment to the list in loadAll, because the list is of the wrong type.
How do I fix this? I want the AU_PaymentDB class to only act upon AU_Payments, and I need the loadAll to be able to add new AU_Payments to the list that is passed in.
I hope this all makes sense,
Chris

ok, I'm assuming that you just forgot to paste in that AU_PaymentDB implements PaymentDB :-)
parameterize AU_PaymentDB as follows:
public class AU_PaymentDB implements PaymentDB<AU_Payment> {
public Result load(Connection conn, AU_Payment payment, ResultInfo resultInfo) throws SQLException {
    return null;
public Result loadAll(Connection conn, List<AU_Payment> payment, ResultInfo resultInfo) throws SQLException {
    return null;
}so the interface defines a looser parameter ( Payment ) and your implementation drills it down to more specifically AU_Payment
Bob, I believe, is your uncle

About interface and Inheritance

First I start a project called Person which contain a person's name, SIN
number and year of birth
import java.io.*;
public class Person implements Create{
String name, sin;
int year;
public void Person(String inName, String inSin, int inYear){
name = inName;
sin = inSin;
year = inYear;
public void setName(String inName){
name = inName;
public void setSin(String inSin){
sin = inSin;
public void setYear(int inYear){
year = inYear;
public String getName(){
return name;
public String getSin(){
return sin;
public int getYear(){
return year;
public String toString(){
return getClass().getName() + name + " " + sin + " " + year;
then I create a class name student
public class Student extends Person{
String major;
double gpa;
public void student(String inMajor, double inGpa){
major = inMajor;
gpa = inGpa;
public void setMajor(String inMajor){
major = inMajor;
public void setGpa(double inGpa){
gpa = inGpa;
public String getMajor(){
return major;
public double getGpa(){
return gpa;
public String toString(){
return super.toString() + " " + major + " " + gpa;
3) Third I create a class name Instructor
import java.io.*;
public class Instructor extends Person{
double salary;
public void Instructor(double inSalary){
salary = inSalary;
public void setSalary(double inSalary){
salary = inSalary;
public double getSalary(){
return salary;
public String toString(){
return super.toString() + " " + salary;
last, I have to create an interface for the person's class...but the
complier dont let me put main or init into the interface class..what is my
problem..how can I fix it?....What am I miss so that I can use the person + student and person +
instructor class..I know I should ask too specificly because it's my
work...but I'm stuck in this area for a long time and the note I have it's
not clear enough...Thank you all...
import java.io.*;
public interface Create{

Thx for the help guys!!
1)..ok.. I have correct the void thingy...
2) ..I want to create and interface class called create which creates a person, a student and an instructor and write out their properties....
something like
Person
Name: Alan
Sin: 1212112
Year of bitrh: 1990
Student
Name: Linda
Sin:121212121
year of birth: 1988
Major: Com. Sci.
Gpa: 4.0
etc..
again...thx for all the help!!! ^^

Question about casting and inheritances

Hi everyone!
I have a class dog which extends the class animal. Apart from that, there is a method called dogsFarm which returns a collection of animals (this method corresponds to another class, let's say farm). I can't touch the inside of that method since I just have the interface but I need a collection of dogs instead of a collection of animals. I tried to cast:
Collection<dog> dogs = (collection<dog>) dogsFarm();But it says that it cannot cast that. Is it any way to solve this without having to change the method?
Thanks

Strictly speaking if the method returns a Collection<Animal>, then no amount of casting will turn it into a Collection<Dog> while still being type safe.
The problem is that a Collection<Animal> could contain a Cat and if you cast it to a Collection<Dog>, it would contain an invalid value.
You could use raw types (i.e. simply "Collection") to "forget" the generic type information and provide new one after that, but that's just an ugly hack that provides no real check.
You could also use Collections.checkedCollection() to provide explicit checks.
You can combine those two techniques to get code that's still ugly, but does at least some error checking:
Collection rawFarm = dogFarm();
Collection<Dog> = Collections.checkedCollection(rawFarm, Dog.class);

Question about constructors and inheritance

Hello:
I have these classes:
public class TIntP4
    protected int val=0;
    public TIntP4(){val=0;}
    public TIntP4(int var)throws Exception
        if(var<0){throw new Exception("TIntP4: value must be positive: "+var);}
        val=var;
    public TIntP4(String var)throws Exception
        this(Integer.parseInt(var));
    public String toString()
        return val+"";
public class TVF extends TIntP4
}Using those clases, if I try to compile this:
TVF inst=new TVF("12");I get a compiler error: TVF(String) constructor can not be found. I wonder why constructor is not inherited, or if there is a way to avoid this problem without having to add the constructor to the subclass:
public class TVF extends TIntP4
     public TVF (String var)throws Exception
          super(var);
}Thanks!!

I guess that it would not help adding the default constructor:
public class TVF extends TIntP4
     public TVF ()
           super();
     public TVF (String var)throws Exception
          super(var);
}The point is that if I had in my super class 4 constructors, should I implement them all in the subclass although I just call the super class constructors?
Thanks again!

First Try with JE BDB - Indexes and Inheritance troubles... (FIXED)

Hi Mark,
Mark wrote:
Hi, I'm a newbie here trying some stuff on JE BDB. And now I'm having
I am happy to help you with this, but I'll have to ask you to re-post this question to the BDB JE forum, which is...
Sorry for the mistake. I know now that here is the place to post my doubts.
I'm really interested in JE BDB product. I think it is fantastic!
Regarding my first post about "Indexes and Inheritance" on JE BDB, I found out the fix for that and actually, it wasn't about "Indexes and Inheritance" but "*Inheritance and Sequence*" because I have my "@Persistent public abstract class AbstractEntity" with a "@PrimaryKey(sequence = "ID_SEQ") private Long id" property.
This class is extended by all my business classes (@Entity Employee and @Entity Department) so that my business classes have their PrimaryKey autoincremented by the sequence.
But, all my business classes have the same Sequence Name: "ID_SEQ" then, when I start running my JE BDB at first time, I start saving 3 new Department objects and the sequence for these department objects star with "#1" and finishes with #3.
Then I continue saving Employee objects (here was the problem) I thought that my next Sequence number could be #4 but actually it was #101 so when I tried to save my very first Employee, I set the property "managerId=null" since this employee is the Manager, then, when I tried to save my second Employee who is working under the first one (the manager employee), I got the following exception message:
TryingJEBDBApp DatabaseExcaption: com.sleepycat.je.ForeignConstraintException: (JE 4.0.71) Secondary persist#EntityStoreName#com.dmp.gamblit.persistence.BDB.store.eployee.Employee#*managerId*
foreign key not allowed: it is not present in the foreign database
persist#EntityStoreName#com.dmp.gamblit.persistence.BDB.store.eployee.Employee
The solution:
I fixed it modifying the managerId value from "4" to "101" and it works now!
At this moment I'm trying to understand the Sequence mechanism and refining concerns about Cursors manipulation...
Have you any good material about these topics, perhaps a link where I can find more detailed information on these?
Thanks in advance Mark, thanks for your attention on this and I will post more doubts in the future for sure ;0)
Regards,
Diego

Hi Diego,
I fixed it modifying the managerId value from "4" to "101" and it works now!I'm glad you found the problem. It is usually best to get the assigned ID from the entity object after you call put(), and then use that value to fill in related fields in other entities. The primary key field (assigned from the sequence) is set by the put() method.
At this moment I'm trying to understand the Sequence mechanism and refining concerns about Cursors manipulation...Have you any good material about these topics, perhaps a link where I can find more detailed information on these? >
To find documentation, start at the first message in the forum, the Welcome message:
http://forums.oracle.com/forums/ann.jspa?annID=250
This refers to the main JE doc page, the JE FAQ and a white paper on DPL queries. The FAQ has a section on the DPL, which refers to the javadoc. The DPL javadoc has lots of info on using cursors along with indexes (see EntityIndex, PrimaryIndex, SecondaryIndex). The white paper will be useful to you if you're accustomed to using SQL.
I don't know of any doc on sequences other than the javadoc:
http://www.oracle.com/technology/documentation/berkeley-db/je/java/com/sleepycat/persist/model/PrimaryKey.html#sequence()
This doc will point you to info on configuring the sequence, if that's what you're interested in.
--mark

Is it possible to create web services for classes and bol objects?

i am new to crm web channel,can any one please ,help me....
thank u in advance,
kiran.

Hi Kiran,
Here, when you are talking about classes and BOL objects together, I assume you are talking about the BOL layer for CRM. If that is the case, and you have no dependency on WCEM for these objects, I would suggest you use the NW gateway to expose Odata web services from the CRM box itself. If you would like to expose the Odata web services from WCEM, please have a look at Ch 7 Dev & Extension Guide available in help.sap.com/wec301.
Good luck!
Regards
Pranshu

Learning about classes

Hi,
I'm working my way through "The Java Programming Language, Fourth Editition" by Sun Microsystems. There are exercises through the book, but they don't give the solutions (which is helpful!!!).
They show a simple class, then ask you to produce an identical one to keep track of vehicles. Based on their sample code this should be the code:
class Vehicle {
     public int speed;
     public String direction;
     public String owner;
     public long idNum;
     public static long nextID = 0;
}Then then ask you to write a class called LinkedList giving no coding examples 'that has a field type Object and a reference to the next LinkedList element in the list. Can someone help me to decipher what this means and the appropriate code?
They then show how to create objects linked to the vehicle class, which based on their sample code should be
Vehicle car = new Vehicle();
car.idNum = Vehicle.nextID++;
car.speed = 120
car.direction = "North"
car.owner = "Metalhead":
This is the bit that next confuses me. They ask you to write a main method for your Vehicle class that creates a few vehicles and prints their field values.
The next exercise is to write a main method for LinkedList class that creates a few objects of type vehicle and places them into successive nodes in the list.
Is'nt it correct that the above code starting 'Vehicle car' would be the code used to create the object which would go in the LinkerList calling on the Vehicle method which has already been defined? For example, successive entries could be for bus, bike etc in the LinkerList. What does it mean though to place these into successive 'nodes' on the list? And why would you create vehicles in the main method of the Vehicle class. Shouldn't they just be created in the LinkerList?
I'm only learning about classes and I'm confused already?
Any help (and code) would be great!!!!
Thanks for any help,
Tim
p.s. I know what I have written sounds vague, bu the book doesn't really give much extra helpful info.

First of all, the variables of the "Vehicle" class should all be private.
You should not be able to directly retrieve each variable from this class
Example:
Vehicle car = new Vehicle();
car.idNum = Vehicle.nextID++;
car.speed = 120
car.direction = "North"
car.owner = "Metalhead"You should have methods that can change this data as well as retrieve the data.
Example:
class Vehicle {
     private int speed;
     private String direction;
     private String owner;
     private static long nextID = 0;
        public Vehicle() {
            speed = 0;
            direction = "";
            owner = "";
            ++nextID;
        // These methods retrieve the attributes
     public int getSpeed() { return speed; }
        public String getDirection() { return new String(direction);}
        public String getOwner() { return new String(owner);}
        public long getidNum() { return idNum; }
        // These methods change the attributes
     public int setSpeed(int i) { speed = i; }
        public String setDirection(String s) { direction = new String(s); }
        public String setOwner(String s) { owner = new String(s); }
}Now, they want you to create another CLASS that shows what your Vehicle class can do.
Example:
public class SomeRandomExampleClass {
    public static void main(String[] args) {
        Vehicle v1 = new Vehicle();
        // Now let's fix up our vehicle
        v1.setSpeed(100);
        v1.setOwner("Zeus");
        v1.setDirection("North");
        // Do note that since idNum is a static variable, it will be increased everytime you create
        // an instance of a Vehicle, and works with the class rather than the object.
        // For instance, if you create Vehicle's v1, v2, and v3, then v1's idNum = 1, v2's idNum = 2;
        // and v3's idNum = 3.
        Vehicle v2 = new Vehicle() ;
        v2.setSpeed(500);
        v2.setOwner("Ricky Bobby");
        v2.setDirection("NorthEast");
        System.out.println(v1.getSpeed()); // prints v1's speed.
        System.out.println(v1.getOwner()); // prints Owner
        System.out.println(v1.getDirection); // Prints Direction
        System.out.println(v1.getidNum()); // prints idNum
        System.out.println(v2.getSpeed()); // prints v1's speed.
        System.out.println(v2.getOwner()); // prints Owner
        System.out.println(v2.getDirection); // Prints Direction
        System.out.println(v2.getidNum()); // prints idNum
}A linked list is what it sounds like. It can hold a list of (let's say vehicles) and you can print their
attributes from there.
For instance, let's say we have a list called list1.
list1.add(vehicle1);
list1.add(vehicle2);
Then you can iterate(move) through your list and print the attributes of each vehicle, instead of having to
call v1.doThis() v1.doThis(), v2.doThis().
I find it amusing they want you to create a LinkedList when you are first using/learning classes.
To understand how to create a linked list, you can visit:
http://leepoint.net/notes-java/data/collections/lists/simple-linked-list.html
Or you can use:
http://java.sun.com/j2se/1.4.2/docs/api/java/util/LinkedList.html
*Note: I wrote the code from nothing so some of it could have syntax errors.

About classes and Inheritance

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