Using UML while designing Object oriented design in ABAP

Hi,
Is it a general practice in projects to use UML diagrams when you do OO design for a report in ABAP ? Or do people start writing th OO code directly ?
Reards,
Rajesh

Hi Rajesh,
In my particular case, I use to start writing the code directly after I read and check the documentation. Right now i'm starting to looking around in order to get more experience in OO programming.
I think that UML is the best option right now, also SAP recommends it. They worked with Rational Software in order to provide an external modeling tool to supports SAP's class.
Check this link in order to get more information.
<a href="http://www.sapinsideronline.com/archive/volume_03_(2002)/issue_03_(july-september)/v3i3a11.cfm?session=&promo=iz1321">http://www.sapinsideronline.com/archive/volume_03_(2002)/issue_03_(july-september)/v3i3a11.cfm?session=&promo=iz1321</a>
Regards,
Eric

Similar Messages

Exception Handling in Object Oriented Design

I am developing a huge web based project using Object Oriented design and java,srvlets ,jsp etc ,I am using 3-tier archtecture.I dont understand,how i should handle exceptions in my project.ie.If there is some exception in the base modules how should it be handled.What kind of excpetion Structure should i use,How many exception classes should be made etc,
Can someone help me in this regard

A couple things I have found to be good practices for exception handling in an n-tier architecture:
1. Don't expose all the internal exceptions of a tier to the client of the tier. Create a more useful, descriptive set of exceptions (or use the appropriate predefined exceptions) to throw up to the client.
For example, on one project, we are doing database access among other things in the "service" tier, which is accessed by the web tier. We catch the SQLExceptions, PersistenceExceptions (a custom exception), and others, and throw a more useful exception that the client will know how to handle such as a NoMeasurementResultsException if the client asks for measurement results when we have none.
2. Chain your exceptions and/or log the root cause in the tier that re-throws a different exception. There is nothing more aggravating than not knowing why, when you are debugging a problem, you are getting a NoMeasurementResultsException when you know that there ARE results in the database.
Hope these ideas help in your design.
Cheers,
Colin

Good book on Object Oriented Design?

Can you recommend a good book on Object Oriented Design with lots of practical examples? I already have:
http://www.amazon.com/Design-Patterns-Object-Oriented-Addison-Wesley-Professional/dp/0201633612/ref=sr_1_1?ie=UTF8&qid=1238324375&sr=8-1
But currently I need a book with a more basic approach.

corlettk wrote:
I like Thinking In Java... Also: google for "yawmark's list"TIJ is useless, especially for teaching OO design. It teaches (or tries to) Java as a procedural language.

Notes on using Object oriented concept in ABAP

Hi ,
I want somes notes on how to use Object oriented concept in ABAP.
Thanks in advance.
Chetan

Hi, this may help you
OOPs ABAP uses Classes and Interfaces which uses Methods and events.
If you have Java skills it is advantage for you.
There are Local classes as well as Global Classes.
Local classes we can work in SE38 straight away.
But mostly it is better to use the Global classes.
Global Classes or Interfaces are to be created in SE24.
SAP already given some predefined classes and Interfaces.
This OOPS concepts very useful for writing BADI's also.
So first create a class in SE 24.
Define attributes, Methods for that class.
Define parameters for that Method.
You can define event handlers also to handle the messages.
After creation in each method write the code.
Methods are similar to ABAP PERFORM -FORM statements.
After the creation of CLass and methods come to SE38 and create the program.
In the program create a object type ref to that class and with the help of that Object call the methods of that Class and display the data.
Example:
REPORT sapmz_hf_alv_grid .
Type pool for icons - used in the toolbar
TYPE-POOLS: icon.
TABLES: zsflight.
To allow the declaration of o_event_receiver before the
lcl_event_receiver class is defined, decale it as deferred in the
start of the program
CLASS lcl_event_receiver DEFINITION DEFERRED.
G L O B A L I N T E R N A L T A B L E S
*DATA: gi_sflight TYPE STANDARD TABLE OF sflight.
To include a traffic light and/or color a line the structure of the
table must include fields for the traffic light and/or the color
TYPES: BEGIN OF st_sflight.
INCLUDE STRUCTURE zsflight.
Field for traffic light
TYPES: traffic_light TYPE c.
Field for line color
types: line_color(4) type c.
TYPES: END OF st_sflight.
TYPES: tt_sflight TYPE STANDARD TABLE OF st_sflight.
DATA: gi_sflight TYPE tt_sflight.
G L O B A L D A T A
DATA: ok_code LIKE sy-ucomm,
Work area for internal table
g_wa_sflight TYPE st_sflight,
ALV control: Layout structure
gs_layout TYPE lvc_s_layo.
Declare reference variables to the ALV grid and the container
DATA:
go_grid TYPE REF TO cl_gui_alv_grid,
go_custom_container TYPE REF TO cl_gui_custom_container,
o_event_receiver TYPE REF TO lcl_event_receiver.
DATA:
Work area for screen 200
g_screen200 LIKE zsflight.
Data for storing information about selected rows in the grid
DATA:
Internal table
gi_index_rows TYPE lvc_t_row,
Information about 1 row
g_selected_row LIKE lvc_s_row.
C L A S S E S
CLASS lcl_event_receiver DEFINITION.
PUBLIC SECTION.
METHODS:
handle_toolbar FOR EVENT toolbar OF cl_gui_alv_grid
IMPORTING
e_object e_interactive,
handle_user_command FOR EVENT user_command OF cl_gui_alv_grid
IMPORTING e_ucomm.
ENDCLASS.
CLASS lcl_event_receiver IMPLEMENTATION
CLASS lcl_event_receiver IMPLEMENTATION.
METHOD handle_toolbar.
Event handler method for event toolbar.
CONSTANTS:
Constants for button type
c_button_normal TYPE i VALUE 0,
c_menu_and_default_button TYPE i VALUE 1,
c_menu TYPE i VALUE 2,
c_separator TYPE i VALUE 3,
c_radio_button TYPE i VALUE 4,
c_checkbox TYPE i VALUE 5,
c_menu_entry TYPE i VALUE 6.
DATA:
ls_toolbar TYPE stb_button.
Append seperator to the normal toolbar
CLEAR ls_toolbar.
MOVE c_separator TO ls_toolbar-butn_type..
APPEND ls_toolbar TO e_object->mt_toolbar.
Append a new button that to the toolbar. Use E_OBJECT of
event toolbar. E_OBJECT is of type CL_ALV_EVENT_TOOLBAR_SET.
This class has one attribute MT_TOOLBAR which is of table type
TTB_BUTTON. The structure is STB_BUTTON
CLEAR ls_toolbar.
MOVE 'CHANGE' TO ls_toolbar-function.
MOVE icon_change TO ls_toolbar-icon.
MOVE 'Change flight' TO ls_toolbar-quickinfo.
MOVE 'Change' TO ls_toolbar-text.
MOVE ' ' TO ls_toolbar-disabled.
APPEND ls_toolbar TO e_object->mt_toolbar.
ENDMETHOD.
METHOD handle_user_command.
Handle own functions defined in the toolbar
CASE e_ucomm.
WHEN 'CHANGE'.
PERFORM change_flight.
LEAVE TO SCREEN 0.
ENDCASE.
ENDMETHOD.
ENDCLASS.
S T A R T - O F - S E L E C T I O N.
START-OF-SELECTION.
SET SCREEN '100'.
*& Module USER_COMMAND_0100 INPUT
MODULE user_command_0100 INPUT.
CASE ok_code.
WHEN 'EXIT'.
LEAVE TO SCREEN 0.
ENDCASE.
ENDMODULE. " USER_COMMAND_0100 INPUT
*& Module STATUS_0100 OUTPUT
MODULE status_0100 OUTPUT.
DATA:
For parameter IS_VARIANT that is sued to set up options for storing
the grid layout as a variant in method set_table_for_first_display
l_layout TYPE disvariant,
Utillity field
l_lines TYPE i.
After returning from screen 200 the line that was selected before
going to screen 200, should be selected again. The table gi_index_rows
was the output table from the GET_SELECTED_ROWS method in form
CHANGE_FLIGHT
DESCRIBE TABLE gi_index_rows LINES l_lines.
IF l_lines > 0.
CALL METHOD go_grid->set_selected_rows
EXPORTING
it_index_rows = gi_index_rows.
CALL METHOD cl_gui_cfw=>flush.
REFRESH gi_index_rows.
ENDIF.
Read data and create objects
IF go_custom_container IS INITIAL.
Read data from datbase table
PERFORM get_data.
Create objects for container and ALV grid
CREATE OBJECT go_custom_container
EXPORTING container_name = 'ALV_CONTAINER'.
CREATE OBJECT go_grid
EXPORTING
i_parent = go_custom_container.
Create object for event_receiver class
and set handlers
CREATE OBJECT o_event_receiver.
SET HANDLER o_event_receiver->handle_user_command FOR go_grid.
SET HANDLER o_event_receiver->handle_toolbar FOR go_grid.
Layout (Variant) for ALV grid
l_layout-report = sy-repid. "Layout fo report
Setup the grid layout using a variable of structure lvc_s_layo
Set grid title
gs_layout-grid_title = 'Flights'.
Selection mode - Single row without buttons
(This is the default mode
gs_layout-sel_mode = 'B'.
Name of the exception field (Traffic light field) and the color
field + set the exception and color field of the table
gs_layout-excp_fname = 'TRAFFIC_LIGHT'.
gs_layout-info_fname = 'LINE_COLOR'.
LOOP AT gi_sflight INTO g_wa_sflight.
IF g_wa_sflight-paymentsum < 100000.
Value of traffic light field
g_wa_sflight-traffic_light = '1'.
Value of color field:
C = Color, 6=Color 1=Intesified on, 0: Inverse display off
g_wa_sflight-line_color = 'C610'.
ELSEIF g_wa_sflight-paymentsum => 100000 AND
g_wa_sflight-paymentsum < 1000000.
g_wa_sflight-traffic_light = '2'.
ELSE.
g_wa_sflight-traffic_light = '3'.
ENDIF.
MODIFY gi_sflight FROM g_wa_sflight.
ENDLOOP.
Grid setup for first display
CALL METHOD go_grid->set_table_for_first_display
EXPORTING i_structure_name = 'SFLIGHT'
is_variant = l_layout
i_save = 'A'
is_layout = gs_layout
CHANGING it_outtab = gi_sflight.
*-- End of grid setup -
Raise event toolbar to show the modified toolbar
CALL METHOD go_grid->set_toolbar_interactive.
Set focus to the grid. This is not necessary in this
example as there is only one control on the screen
CALL METHOD cl_gui_control=>set_focus EXPORTING control = go_grid.
ENDIF.
ENDMODULE. " STATUS_0100 OUTPUT
*& Module USER_COMMAND_0200 INPUT
MODULE user_command_0200 INPUT.
CASE ok_code.
WHEN 'EXIT200'.
LEAVE TO SCREEN 100.
WHEN'SAVE'.
PERFORM save_changes.
ENDCASE.
ENDMODULE. " USER_COMMAND_0200 INPUT
*& Form get_data
FORM get_data.
Read data from table SFLIGHT
SELECT *
FROM zsflight
INTO TABLE gi_sflight.
ENDFORM. " load_data_into_grid
*& Form change_flight
Reads the contents of the selected row in the grid, ans transfers
the data to screen 200, where it can be changed and saved.
FORM change_flight.
DATA:l_lines TYPE i.
REFRESH gi_index_rows.
CLEAR g_selected_row.
Read index of selected rows
CALL METHOD go_grid->get_selected_rows
IMPORTING
et_index_rows = gi_index_rows.
Check if any row are selected at all. If not
table gi_index_rows will be empty
DESCRIBE TABLE gi_index_rows LINES l_lines.
IF l_lines = 0.
CALL FUNCTION 'POPUP_TO_DISPLAY_TEXT'
EXPORTING
textline1 = 'You must choose a line'.
EXIT.
ENDIF.
Read indexes of selected rows. In this example only one
row can be selected as we are using gs_layout-sel_mode = 'B',
so it is only ncessary to read the first entry in
table gi_index_rows
LOOP AT gi_index_rows INTO g_selected_row.
IF sy-tabix = 1.
READ TABLE gi_sflight INDEX g_selected_row-index INTO g_wa_sflight.
ENDIF.
ENDLOOP.
Transfer data from the selected row to screenm 200 and show
screen 200
CLEAR g_screen200.
MOVE-CORRESPONDING g_wa_sflight TO g_screen200.
LEAVE TO SCREEN '200'.
ENDFORM. " change_flight
*& Form save_changes
Changes made in screen 200 are written to the datbase table
zsflight, and to the grid table gi_sflight, and the grid is
updated with method refresh_table_display to display the changes
FORM save_changes.
DATA: l_traffic_light TYPE c.
Update traffic light field
Update database table
MODIFY zsflight FROM g_screen200.
Update grid table , traffic light field and color field.
Note that it is necessary to use structure g_wa_sflight
for the update, as the screen structure does not have a
traffic light field
MOVE-CORRESPONDING g_screen200 TO g_wa_sflight.
IF g_wa_sflight-paymentsum < 100000.
g_wa_sflight-traffic_light = '1'.
C = Color, 6=Color 1=Intesified on, 0: Inverse display off
g_wa_sflight-line_color = 'C610'.
ELSEIF g_wa_sflight-paymentsum => 100000 AND
g_wa_sflight-paymentsum < 1000000.
g_wa_sflight-traffic_light = '2'.
clear g_wa_sflight-line_color.
ELSE.
g_wa_sflight-traffic_light = '3'.
clear g_wa_sflight-line_color.
ENDIF.
MODIFY gi_sflight INDEX g_selected_row-index FROM g_wa_sflight.
Refresh grid
CALL METHOD go_grid->refresh_table_display.
CALL METHOD cl_gui_cfw=>flush.
LEAVE TO SCREEN '100'.
ENDFORM. " save_changes
chk this blog
/people/vijaybabu.dudla/blog/2006/07/21/topofpage-in-alv-using-clguialvgrid
Reward if helpfull.
Regards Madhu.

Who has the book:Object-Oriented Programming with ABAP Objects

Hello everyone
Now i want to learn ABAP OO,and Lots' of guys told me that the book Object-Oriented Programming with ABAP Objects is realy a good book.but i searched on the net,and could not got PDF of this book,could some one gave me the net address if you know where to download the book or send me to my Mailbox:<email id removed by moderator>,I will very glad to receive any response from you,
of course,if you have some advise on how to learn ABAP OO or some other material ,hope you could share your meaning with me, hope to receive your response.
Best regards!
From Carl
Moderator message : Moved to career center.
Edited by: Vinod Kumar on Aug 27, 2011 9:21 AM

I'm sure you're not asking for illegal, "free" downloads. You can legally purchase the book, also in electronic format, at sap-press.com
Thomas

Material for Object Oriented Concepts in ABAP

Hi,
Please provide me the material for Object Oriented Concepts in ABAP.

Hi
Please check this link, may be helpful
http://www.sap-img.com/ab029.htm
http://help.sap.com/saphelp_nw04/helpdata/en/c3/225b5654f411d194a60000e8353423/content.htm
http://help.sap.com/saphelp_nw2004s/helpdata/en/c3/225b5654f411d194a60000e8353423/frameset.htm
http://help.sap.com/saphelp_nw2004s/helpdata/en/c3/225b5654f411d194a60000e8353423/content.htm
regards
Srinivas

Question about Object Oriented Design in Oracle

Hi everyone,
Right now I'm updating my oracle skills, years ago without programming (last time with Oracle 7.3 :O)
Well, if I have to design a new system with this features:
1.- Using Oracle as DB
2.- Web enable
3.- OO Design
My questions:
1.- What is the best practice to make database design? E-R + Object Types? I mean is better making the design on Oracle directly or in Java-UML environment?
2.- I was thinking in programming with Forms, but it works well with OO design?
3.- If I want to program some web services based, Could I do it with PL/SQL and Jdeveloper?
please if you know about articles and whitepapers about OO design approach with Oracle let me know!
Thanks.

I have been involved in some of these projects that have used Java, C#, VB, C++ etc. as front-end languagaes. I have been able to implement these projects successfully using the following approach:
1. create a relational model of the database - third-normal form (assuming it is an OLTP application)
2. Write PL/SQL code (packages and procedures mainly)
3. Interact with the front-end layer by sending and receiving ref curosors and/or PL/SQL tables
If you want to use Forms (I am assuming Oracle Forms) then there may not be much need for an OO design. Embeeding SQL in the forms will do most of what you want.
Shakti
http://www.impact-sol.com
Developers of Guggi Oracle - Tool for DBAs and Developers

Backing Beans Object Oriented Design

Hello,
Are there any best practices for using Backing Beans?
How to make managed beans thread-safe for concurrent requests,
without compromising on efficiency/speed?
2. How to enforce the J2EE security with backing-beans?
3. How to decide the scope of these beans to ensure minimal data-storage
in session?
4. How to decide the granularity at which a managed-bean should be used
for example :
4.1 One bean-per-component
4.2 One bean-per-form
4.3 One bean-per-page
Also i would like to know how to design managed beans from reusability perspective.
Regards,
Smita

It quite hard to give a brief answer on all your questions.
I think that you should take into account bean's scope when think about thread safety.
Request scope bean is single threaded while for session scope you should provide locking mechanism because this bean can be accessed from different threads but only in case when one user simultaneously submit request from multiply browser windows.
As for security you can use standard security API from within bean through javax.faces.context.ExternalContext
It is convenient to use one backing bean for some or all components in web form.
Do not mix form component and business data in one bean. Thus it is good design to have one set of beans for presentation logic and another one for business logic.

Theoretical object oriented design question

Hi,
I am just getting into the design of some software that will take either one or two numbers and perform identical operations on them. It will then create a label that will be different depending on whether 1 or 2 serial numbers are used.
In the example it looks like I could make a vehicle class that would contain the serial number, and child classes for car, truck and boat that would define how the sticker was laid out.
The trouble I am having is that the control for serial number 1 and serial number 2 need to accept any of the three numbers for car truck and boat.
So I am not sure how to build classes to cover this, and what design pattern would be best.
So I am looking for ideas.
I have no real code yet to post, and a lot of the attributes are confidential, which is why I made the simple diagram.

Search this site for...
Factory Pattern
It basiclly uses a case sctructure to to select a Class constant of the proper type.
Have fun!
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

Object oriented design problem concerning abstract classes and interfaces

I have an abstract class (class A) that takes care of database connections. It cannot be made into an interface as other classes extend it and all these other classes require the functionality in the methods it has (i.e. I cannot make all the methods abstract and then make this class an interface).
I have a class that contains data (Customer class) that I will create from the data I extract from the database. This class will also be created by the User and submitted to the database portion of the program. The Customer class has functionality in its methods which is required by the rest of the program (i.e. I cannot make all the methods abstract and then make this class an interface).
I have a factory class (CustomerFactory) that extends the Customer class. This has been created to restrict access to the creation and manipulation of Customers.
I have a class (DatabaseQuery) that extends class A. But now that I have retrieved all of the information that comprises a Customer from the database, I cannot construct a Customer without making reference to UserFactory. But UserFactory is a class that I don't want the database portion of the program to know about.
What I would like to do is have my DatabaseQuery class extend both Customer class and A class. But they are both classes and Java won't allow that.
I can't make either of the two classes that I want to make parents of DatabaseQuery into interfaces... so what can I do other than just keep a reference to UserFactory in my DatabaseQuery class?
Thanks,
Tim

>
What I would like to do is have my DatabaseQuery class
extend both Customer class and A class. But they are
both classes and Java won't allow that.
I can't make either of the two classes that I want to
make parents of DatabaseQuery into interfaces... so
what can I do other than just keep a reference to
UserFactory in my DatabaseQuery class?Just a guess...
The description sounds a little vague but it sounds like the correct solution would be to refactor everything. The first clue is when I see "database connection" as an "abstract class". The only hierarchy that a database connection might exist in is in a connection pool and even that is probably shaky. It should never be part of data records, which is what your description sounds like.
That probably isn't what you want to hear.
The other solution, which is why refactoring is better (and which also makes it apparent why the original design is wrong) is to create an entire other hierarchy that mirrors your current data hierarchy and wraps it. So you now have "Customer", you will now have "Customer" and "DBCustomer". And all the code that currently uses "Customer" will have to start using DBCustomer. Actually it is easier than that since you can simply make the new class be "Customer" and rename the old class to "DBCustomer". Naturally that means the new class will have to have all of the functionality of the old class. Fortunately you can use the old class to do that. (But I would guess that isn't going to be easy.)

Object Oriented Design in Java

I am an RPGIV programmer trying to switch to Java. I have some experience with Java syntax and basic fundamentals. My question pertains to OOP specifically. I am trying to write a version of the old C-robots program in java. It was an AI simulation project written in C years ago where you could modify the actual AI code and then implement it to test results with 3 other robots with different AI. My question is this: When trying to break down the methods for an interface client to control the robot objects, how do you know what messages that particular client should take care of. In a GUI version I imagine that all the interface client would need to know is basically getPosition() and getDamage() for the display. Then the robot objects would handle all of the other methods including moving(), scanning() and shooting() just to keep it simple. (many more methods are needed, I know). i guess in a nutshell i am trying to determine good program design when it comes to object responsibility. how much responsibility should the interface have as opposed to the other. thank you

Hi! Welcome to Java. You have a rather broad-based question which primarily deals with good o-o design.
I'd recommend reading the chapters relating to o-o design from Bruce Eckel's "Thinking In Java". The electronic edition of the book is available for free download at http://www.bruceeckel.com.
Now, regarding the interface client, you need to determine what other entities it will interact with and from that determine what methods it must have in order to permit those interactions. That's a rather short way of putting it, I know. However, hopefully that's enough to get you going.
Hope this helps! Feel free to ask if something's not too clear.
Cheers!

Object oriented design -book

Hi
I'm looking for a good book about oo design. I'm interested in a book showing how to divide real-life probleminto set of classes and methods. Explaining few oo design's methods and so on... I would be really greatful if could recommend me such a kind of book?

LOL, thank you scarlet for cheering up my ever so
painful monday morning.Read again. Rene = Frenchman. Scarlet = Limey. I'm
not him.oops, like i said, "i don't like mondays"
humming "...I don't like jamaica, i love it ya...".
I have "Teach yourself the Washing Machine in 21
Days", but I think there's a misprint somewhere. My
clothes don't look like 600�C were a good idea... but
OTOH, maybe I'm doing something wrong. I'm still at
Day 3 (how to undress before washing the clothes).That misprint sucks.
But i'm very interested in how you did wash your clothes on 600�C without finishing day 3 first.
A small hint: I have found the perfect solution so I didn't had to buy that book (I saw it was actually one of the expensive ones in the serie), I got engaged, thinking that would be cheaper.
I couldn't be more off on that one.

Question about Object-Orientated design for GUI'S

Hi everyone,
I am designing a simple GUI, which basically enables a user to input and retreive data.
So I have a prototype GUI lets call it "myFrame". It extends JFrame, and I place my components onto myFrame, JButtons, JTextfields etc. I have the GUI set up the way I want it, so I move onto implementing the actionListeners.
The problem is that one of the components I have placed on myFrame has its own mouseListener. Its a type of Icon (i created in a seperate class)which extends JComponent, and I thought it would be sensible to give it control of its own mouseListener, so it cuts down on the code within the myFrame class.
But I now realise that I can't alter the other components on myFrame from within the mouseListener in the icon class. I know the icon class doesn't have access to any of myFrames methods or instance fields, so how do I correctly implement this. Surely the answer isn't to bung all the code together into one class?
visually what I have so far looks like this
SERVER <---Requests---> myFrame --------> IconList ---------> Icon
the IconList class looks up a server to update its array of Icons[]. But when one individual Icon is clicked on myFrame, i want its mouseListener to load some of its values onto myFrame's GUI components.
I hope I'm making myself clear, im sorry if this seems like a muddled incoherent question, but any advice would be great. I only need to be shown the correct way to design, and then i carry on coding happily. If this kind of design is way off, please let me know!!
Thanks

You can absolutely do work on the frame from the mouse listener--It just needs an instance. i.e.
public class MyMouseListener implements MouseListener {
private MyFrame frame;
public MyMouseListener(MyFrame frame) {
this.frame = frame;
}Does that make sense?
That said, what you'll see more often is a Model-View-Control approach, wherein the Control (the mouse listener in your case) effects the Model and the Model notifies the View to update its display, rather than the Control updating the view directly. That's the extreme overview version, lots of good hits on google if you're interested beyond that

Proper object oriented design for factory class

I have a factory class (UserFactory) it is capable of creating two types of classes (Customer and Employee) that extend User. User is an abstract class.
At present any class could create a Customer of an Employee.
How do I restrict access to the constructors of Customer and Employee only to UserFactory?
I don't want to make both of these classes interfaces (in which case I could just have UserFactory implement both of them).
Here is an example of how they are set up at present:
public abstract class User {
public class Customer extends User{
public Customer{
public class Employee extends User {
public Employee {
public class UserFactory ???? {
private static UserFactory c_userFactory = null;
private UserFactory (){
public UserFactory getInstance(){
//private clone method too
public Customer createCustomer(){
public Employee createEmployee(){
Oh and I don't want to create two separate factory classes for Employee and Customer. In C++ there is a concept of friend classes that would have worked nicely in this case.
Thanks for any and all suggestions,
Tim

So correct me if I'm wrong but your suggestion would be something along the lines of:
public abstract class User {
public class Customer extends User{
protected Customer(){
public class Employee extends User {
protected Employee (){
public class UserFactory ???? {
private static UserFactory c_userFactory = null;
private UserFactory (){
public UserFactory getInstance(){
//private clone method too
public Customer createCustomer(){
public Employee createEmployee(){
public class AccessForCustomer extends Customer {
public class AccessForEmployee extends Employee {
Is the above about what you were talking about? I haven't used inner classes before, so I'm a bit curious. Does this mean no class other than UserFactory or derivatives thereof can access the two classes AccessForCustomer and AccessForEmployee?
Thanks,
Tim

UML diagrams and Object Oriented programming

In a project for CSC120 at school we have to program a casino using java. We were given a UML diagram of how the professor wants it set up, and I am having some difficulty understanding exactly what some of this means, code wise.
Part of the UML diagram:
Game
userMoney: int
bet: int
playAgain() : bool
askBet() : int
Payout(amt: void) : void
takeBet(amt:void) : bool
I understand the first two blocks, but the last one confuses me. I get that these are the different functions the class will use, but what does the text inside the parentheses mean, and the text after the colon? And what would this look like in code? If someone could post a link to an example program it would greatly help, or just post a simple example here.
Here is what I have so far in the class file:
* ASCIIcasino.java
* Version 1.0
* Alachine
* Last Modified: 01/19/2006
public class Game
     int usermoney;
     int bet;
    public boolean playAgain()
    public int askBet ()
         do
               System.out.println("How much do you wish to bet?");
               scannergameinput = new Scanner(System.in);
          while(!scannergameinput.hasNextInt());
          bet = scannergameinput.nextInt();
          System.out.print("Your bet: ");
         return bet;
    public void Payout ()
         int amt;
    public boolean takeBet ()
         int amt;
}Am I doing this correctly so far, or what am I not getting? Thank you for your time.
Edited to update code.
Message was edited by:
Alachine

playAgain() : bool
askBet() : int
Payout(amt: void) : void
takeBet(amt:void) : boolThese are methods of the "Game" class, and what is inside parentheses are called parameters.
"void" and "bool" are return types.
public boolean playAgain()
    }In this code you have specified boolean as a return type, so you need to return a value of type bool.
As for the void part, you don't need to return anything.
Code should look like:
public boolean playAgain()
         return true; //Or return false
public void Payout ()
         int amt;
    }You need to get :int amt" in the parameters, and since its voide nothing needs to be returned.
public void Payout (int amt)
    }

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