Help with interface and abstract

Hi all
what is the difference between an interface and an abstract class??

Suppose if you want to implement all the methods we usually use the interface. if you define a method in the interface you must provide the implementation for this interface in the implementation class.
In case of abstract, we can have both the abstract and non -abstract methods. Means abstract class can have the methods with the implementations defined in that class and abstract methods which needs to be implemented for the sub classes.

Similar Messages

Help with interfaces and Leopard 10.5.2

Forgive me for my "ignorance" on recording but I thought I could get some decent advice in here...
I've been a musician for 10 yrs but never recorded something at home besides midi instruments...It's about time I get to record my guitar...And from what I've been reading, neither Digidesign or MAudio interfaces are compatible with Leopard 10.5.2
I need to buy an interface and would like an opinion...just for small recordings at home. Something like the Firewire Solo or the MBox mini. Does anyone have any preferences? Which one do you think will have drivers released sooner? I'm either gonna run it with Garage or Logic Express.
Thanks in advance for your input!

Barbie Rock,
I personally love the audio interface units by Echo Audio. They are always on top of releasing new drivers when they are called for. I have an Echo Audiofire 12 and it is amazing. But, if you do not need 12 inputs they do have smaller firewire units. The Echo Audiofire2, Audiofire4 and Audiofire8. I have been using Echo Audio products for a long time and I have never had a problem with them. You can visit their website here: http://www.echoaudio.com. Whatever interface you decide on buying, I would strongly suggest not getting something that records over usb. I have had a few different usb devices and I always have problems. Firewire is the way to go.
-Tyler

Need help with interface development

Hi i need help with requirement below with developing interface between or online order system and sap plz lemme know what is bapi i use for creating customer, update and assigining partner id to costumer.
SAP Development
1.     Using standards SAP functional module (with BAPI), create interface that will create/change Ordering party customer in SAP. Following fields are mandatory for customer creation:
     MANDT     Client
     VKORG     Sales organization
     VTWEG     Distribution Channel
     SPART     Division
     KDGRP     Customer Group (= ZORP)
     KUNNR     Customer number
     NAME1     Name 1
     NAME 2     Name 2 (if required)
     SORTL     Search term (short description)
     ZZALTKN     Search term 2 (old customer number)
     LAND1     Country
     ORT01     City
     PSTLZ      Zip Code
     REGIO      Region (state in USA)
     STRAS     Street
     TELF1     Primary telephone number
     TELFX     Primary Fax number
     ZZPRPLANS     Payment Plan
     CCINS     Payment card: Card type
     CCNUM     Payment cards: Card number
     CCDEF     Payment Card: Default Card Indicator
     ZBDGID     Customer Budget ID
     ZHOLD     Budget Hold indicator
     ZZCOSTCENT     Cost Center
2.     Upon successful customer creation system will issues S (success) message that customer has been created.
3.     New ordering party customer created in step ½, will have to be assigned as new partner to its belonging Sold-to/Ship-to customer. Use standard SAP customer functional module in order to perform this partner ID assignment. Partner ID for ordering party should be ZO.
1.7     Enhancement Functionality
Apart from creating a new interface to do the required functionality, the Order Create Interface also has to be changed to accommodate a field to pass the Ordering Party Number on the Order. The technicalities of how we are going to implement the interface will be laid out in the Tech Specs.
Thanks
in advance

You have double posted, please mark this one as "solved on my own" and refer to this thread
need help with interface development
Regards,
Rich Heilman

Help with writing and retrieving data from a table field with type "LCHR"

Hi Experts,
I need help with writing and reading data from a database table field which has a type of "LCHR". I have given an example of the original code but don't know what to change it to in order to fix it and still read in the original data that's stored in the LCHR field.
Basically we have two Function modules, one that saves list data to a database table and one that reads in this data. Both Function modules have an identicle table which has an array of fields from type INT4, CHAR, and type P. The INT4 field is the first one.
Incidentally this worked in the 4.7 non-unicode system but is now dumping in the new ECC6 Unicode system.
Thanks in advance,
C
SAVING THE LIST DATA TO DB
DATA: L_WA(800).
LOOP AT T_TAB into L_WA.
ZDBTAB-DATALEN = STRLEN( L_WA ).
MOVE: L_WA to ZDBTAB-RAWDATA.
ZDBTAB-LINENUM = SY-TABIX.
INSERT ZDBTAB.
READING THE DATA FROM DB
DATA: BEGIN OF T_DATA,
             SEQNR type ZDBTAB-LINENUM,
             DATA type ZDBTAB-RAWDATA,
           END OF T_TAB.
Select the data.
SELECT linenum rawdata from ZDBTAB into table T_DATA
     WHERE repid = w_repname
     AND rundate = w_rundate
     ORDER BY linenum.
Populate calling Internal Table.
LOOP AT T-DATA.
APPEND T_DATA to T_TAB.
ENDLOOP.

Hi Anuj,
The unicode flag is active.
When I run our report and then to try and save the list data a dump is happening at the following point
LOOP AT T_TAB into L_WA.
As I say, T_TAB consists of different fields and field types whereas L_WA is CHAR 800. The dump mentions UC_OBJECTS_NOT_CONVERTIBLE
When I try to load a saved list the dump is happening at the following point
APPEND T_DATA-RAWDATA to T_TAB.
T_DATA-RAWDATA is type LCHR and T_TAB consists of different fields and field types.
In both examples the dumps mention UC_OBJECTS_NOT_CONVERTIBLE
Regards
C

Help with count and sum query

Hi I am using oracle 10g. Trying to aggregate duplicate count records. I have so far:
SELECT 'ST' LEDGER,
CASE
WHEN c.Category = 'E' THEN 'Headcount Exempt'
ELSE 'Headcount Non-Exempt'
END
ACCOUNTS,
CASE WHEN a.COMPANY = 'ZEE' THEN 'OH' ELSE 'NA' END MARKET,
'MARCH_12' AS PERIOD,
COUNT (a.empl_id) head_count
FROM essbase.employee_pubinfo a
LEFT OUTER JOIN MMS_DIST_COPY b
ON a.cost_ctr = TRIM (b.bu)
INNER JOIN MMS_GL_PAY_GROUPS c
ON a.pay_group = c.group_code
WHERE a.employee_status IN ('A', 'L', 'P', 'S')
AND FISCAL_YEAR = '2012'
AND FISCAL_MONTH = 'MARCH'
GROUP BY a.company,
b.district,
a.cost_ctr,
c.category,
a.fiscal_month,
a.fiscal_year;
which gives me same rows with different head_counts. I am trying to combine the same rows as a total (one record). Do I use a subquery?

Hi,
Whenever you have a problem, please post a little sample data (CREATE TABLE and INSERT statements, relevant columns only) from all tables involved.
Also post the results you want from that data, and an explanation of how you get those results from that data, with specific examples.
user610131 wrote:
... which gives me same rows with different head_counts.If they have different head_counts, then the rows are not the same.
I am trying to combine the same rows as a total (one record). Do I use a subquery?Maybe. It's more likely that you need a different GROUP BY clause, since the GROUP BY clause determines how many rows of output there will be. I'll be able to say more after you post the sample data, results, and explanation.
You may want both a sub-query and a different GROUP BY clause. For example:
WITH    got_group_by_columns     AS
     SELECT a.empl_id
     ,     CASE
                    WHEN c.category = 'E'
              THEN 'Headcount Exempt'
                    ELSE 'Headcount Non-Exempt'
            END          AS accounts
     ,      CASE
                    WHEN a.company = 'ZEE'
                    THEN 'OH'
                    ELSE 'NA'
            END          AS market
     FROM              essbase.employee_pubinfo a
     LEFT OUTER JOIN mms_dist_copy             b ON   a.cost_ctr     = TRIM (b.bu)
     INNER JOIN       mms_gl_pay_groups        c ON   a.pay_group      = c.group_code
     WHERE     a.employee_status     IN ('A', 'L', 'P', 'S')
     AND        fiscal_year           = '2012'
     AND        fiscal_month          = 'MARCH'
SELECT    'ST'               AS ledger
,       accounts
,       market
,       'MARCH_12'          AS period
,       COUNT (empl_id)      AS head_count
FROM       got_group_by_columns
GROUP BY accounts
,            market
;But that's just a wild guess.
You said you wanted "Help with count and sum". I see the COUNT, but what do you want with SUM? No doubt this will be clearer after you post the sample data and results.
Edited by: Frank Kulash on Apr 4, 2012 5:31 PM

MOVED: [Athlon64] Need Help with X64 and Promise 20378

This topic has been moved to Operating Systems.
[Athlon64] Need Help with X64 and Promise 20378

I'm moving this the the Administration Forum. It seems more apporpiate there.

Help with encapsulation and a specific case of design

Hello all. I have been playing with Java (my first real language and first OOP language) for a couple months now. Right now I am trying to write my first real application, but I want to design it right and I am smashing my head against the wall with my data structure, specifically with encapsulation.
I go into detail about my app below, but it gets long so for those who don't want to read that far, let me just put these two questions up front:
1) How do principles of encapsulation change when members are complex objects rather than primitives? If the member objects themselves have only primitive members and show good encapsulation, does it make sense to pass a reference to them? Or does good encapsulation demand that I deep-clone all the way to the bottom of my data structure and pass only cloned objects through my top level accessors? Does the analysis change when the structure gets three or four levels deep? Don't DOM structures built of walkable nodes violate basic principles of encapsulation?
2) "Encapsulation" is sometimes used to mean no public members, othertimes to mean no public members AND no setter methods. The reasons for the first are obvious, but why go to the extreme of the latter? More importantly HOW do you go to the extreme of the latter? Would an "updatePrices" method that updates encapsulated member prices based on calculations, taking a single argument of say the time of year be considered a "setter" method that violates the stricter vision of encapsulation?
Even help with just those two questions would be great. For the masochistic, on to my app... The present code is at
http://www.immortalcoil.org/drake/Code.zip
The most basic form of the application is statistics driven flash card software for Japanese Kanji (Chinese characters). For those who do not know, these are ideographic characters that represent concepts rather than sounds. There are a few thousand. In abstract terms, my data structure needs to represent the following.
- There are a bunch of kanji.
   Each kanji is defined by:
   - a single character (the kanji itself); and
   - multiple readings which fall into two categories of "on" and "kun".
      Each reading is defined by:
      - A string of hiragana or katakana (Japanese phoenetic characters); and
      - Statistics that I keep to represent knowledge of that reading/kanji pair.Ideally the structure should be extensible. Later I might want to add statistics associated with the character itself rather than individual readings, for example. Right now I am thinking of building a data structure like so:
- A Vector that holds:
   - custom KanjiEntry objects that each hold
      - a kanji in a primitive char value; and
      - two (on, kun) arrays or Vectors of custom Reading objects that hold
         - the reading in a String; and
         - statistics of some sort, probably in primitive valuesFirst of all, is this approach sensible in the rough outlines?
Now, I need to be able to do the obvious things... save to and load from file, generate tables and views, and edit values. The quesiton of editting values raises the questions I identified above as (1) and (2). Say I want to pull up a reading, quiz the user on it, and update its statistics based on whether the user got it right or wrong. I could do all this through the KanjiEntry object with a setter method that takes a zillion arguments like:
theKanjiEntry.setStatistic(
"on",   // which set of readings
2,      // which element in that array or Vector
"score", // which statistic
98);      // the valueOr I could pass a clone of the Reading object out, work with that, then tell the KanjiEntry to replace the original with my modified clone.
My instincts balk at the first approach, and a little at the second. Doesn't it make more sense to work with a reference to the Reading object? Or is that bad encapsulation?
A second point. When running flash cards, I do not care about the subtlties of the structure, like whether a reading is an on or a kun (although this is important when browsing a table representing the entire structure). All I really care about is kanij/reading pairings. And I should be able to quickly poll the Reading objects to see which ones need quizzing the most, based on their statistics. I was thinking of making a nice neat Hashtable with the keys being the kanji characters in Strings (not the KanjiEntry objects) and the values being the Reading objects. The result would be two indeces to the Reading objects... the basic structure and my ad hoc hashtable for runninq quizzes. Then I would just make sure that they stay in sync in terms of the higher level structure (like if a whole new KanjiEntry got added). Is this bad form, or even downright dangerous?
Apart from good form, the other consideration bouncing around in my head is that if I get all crazy with deep cloning and filling the bottom level guys with instance methods then this puppy is going to get bloated or lag when there are several thousand kanji in memory at once.
Any help would be appreciated.
Drake

Usually by better design. Move methods that use the
getters inside the class that actually has the data....
As a basic rule of thumb:
The one who has the data is the one using it. If
another class needs that data, wonder what for and
consider moving that operation away from that class.
Or move from pull to push: instead of A getting
something from B, have B give it to A as a method
call argument.Thanks for the response. I think I see what you are saying.. in my case it is something like this.
Solution 1 (disfavored):
public class kanjiDrill{ // a chunk of Swing GUI or something
     public void runDrill(Vector kanjiEntries){
          KanjiEntry currentKanjiEntry = kanjiEntries.elementAt(0); // except really I will pick one randomly
          char theKanji = currentKanjiEntry.getKanji();
          String theReading = currentKanjiEntry.getReading();
          // build and show a flashcard based on theKanji and theReading
          // use a setter to change currentKanji's data based on whether the user answers correctly;
}Solution 2 (favored):
public class kanjiDrill{ // a chunk of Swing GUI or something
     public void runDrill(Vector kanjiEntries){
          KanjiEntry currentKanjiEntry = kanjiEntries.elementAt(0); // except really I will pick one randomly
          currentKanji.buildAndShowFlashcard(); // method includes updating stats
}I can definitely see the advantages to this, but two potential reasons to think hard about it occur to me right away. First, if this process is carried out to a sufficient extreme the objects that hold my data end up sucking in all the functionality of my program and my objects stop resembling natural concepts.
In your shopping example, say you want to generate price tags for the items. The price tags can be generated with ONLY the raw price, because we do not want the VAT on them. They are simple GIF graphics that have the price printed on a an irregular polygon. Should all that graphics generating code really go into the item objects, or should we just get the price out of the object with a simple getter method and then make the tags?
My second concern is that the more instance methods I put into my bottom level data objects the bigger they get, and I intend to have thousands of these things in memory. Is there a balance to strike at some point?
It's not really a setter. Outsiders are not setting
the items price - it's rather updating its own price
given an argument. This is exactly how it should be,
see my above point. A breach of encapsulation would
be: another object gets the item price, re-calculates
it using a date it knows, and sets the price again.
You can see yourself that pushing the date into the
item's method is much beter than breaching
encapsulation and getting and setting the price.So the point is not "don't allow access to the members" (which after all you are still doing, albeit less directly) so much as "make sure that any functionality implicated in working with the members is handled within the object," right? Take your shopping example. Say we live in a country where there is no VAT and the app will never be used internationally. Then we would resort to a simple setter/getter scheme, right? Or is the answer that if the object really is pure data are almost so, then it should be turned into a standard java.util collection instead of a custom class?
Thanks for the help.
Drake

I need help with Applets and Multithreading

[hello all. first time poster. big fan of java.]
now to the important matter: Applets and Threads
=======================================
1) I have an applet with that implements the runnable interface, and has one thread (and a simple animation). If I try to view this applet in the applet viewer with JGrasp, it spits an insane error telling me
"java.security.AccessControlException: access denied (java.lang.RuntimePermission modifyThreadGroup)"
but, if I run the applet through a web browser, by putting it in an html document, it runs correctly, without error
What on earth is wrong, and how do I fix it?!?
2) I want to put 2 threads in my applet?
If I implement the Runnable interface, I can only have one Run() method in my applet, right?
So how do I define behaviour for 2 threads when I only have one run method in which to define the behaviour? Can I use two threads with the runnable interface, or do I have to make objects of my own defined thread classes?
3) I tried to make 2 threads in my applet by creating my own thread classes, and instantiating them in my applet (instead of implementing the runnable interface).
I still get the same insane error as I mentioned in my first point (which I expected), except now, the applet won't work even when viewed through a web browser!!
Please please help me. I am frustrated beyond belief (at what is probably a very simple problem)
I have searched and searched all over and found no answers on this

If I try to view this applet in the applet viewer with JGrasp, it spits an insane error telling me
"java.security.AccessControlException: access denied (java.lang.RuntimePermission modifyThreadGroup)"Don't know anything about JGrasp, but it runs with pretty tight security - thats what this insane error is all about. Use the appletviewer or a browser.
If I implement the Runnable interface, I can only have one Run() method in my applet, right?Correct
So how do I define behaviour for 2 threads when I only have one run method in which to define the behaviour?
Can I use two threads with the runnable interface, or do I have to make objects of my own defined thread classes?You can create two Runnable implementations (classes) in your applet.
example (missing code)
class MyApplet extends Applet {
void doSomething() {
void doSomethingElse() {
void startThreads() {
    Thread t = new Thread(new Runnable() { public void run() { doSomething();}});
    t.start();
    t = new Thread(new Runnable2());
    t.start();
class Runnable2 implements Runnable {
     public void run() {
       doSomethingElse();
}If the above seems confusing, read up on anonymous and inner classes.
3) I tried to make 2 threads in my applet by creating my own thread classesTry not subclassing thread - this causes a security check

Using Search Help with ALV and Dynamic context node

The topic subject already describes my situation.
I have to create, populate and remove context nodes at runtime, and bind them to an ALV, to let user display the data or modify the data. The nodes I create are always typed with a table name, but the table name is of course, dynamic.
This is all working: what's not working is help for entries inside the ALV; since the table has foreign keys and domains with check tables or fixed values, I expected that search helps were detected and managed by the framework.
Instead, no help search is displayed except the input help based on data-type of the one "Date" input fields.
I think I have to work on the dynamic node creation, and not on the ALV itself, since the latter only takes the node/attributes information, but i could be wrong. I tried with both the two following codings:
CALL METHOD lo_nd_info_root->add_new_child_node
    EXPORTING
      static_element_type          = vs_tabname
      name                         = 'SAMPLE_NODE_NAME'
*    is_mandatory                 = abap_false
*    is_mandatory_selection       = abap_false
     is_multiple                  = abap_true
     is_multiple_selection        = abap_false
*    is_singleton                 = abap_false
      is_initialize_lead_selection = abap_false
      is_static                    = abap_false
    RECEIVING
      child_node_info              = lo_nd_info_data .
cl_wd_dynamic_tool=>create_nodeinfo_from_struct(
      parent_info = lo_nd_info_root
      node_name = 'SAMPLE_NODE_NAME'
      structure_name = vs_tabname
      is_multiple = abap_true ).
The result is the same...is there any way to let the ALV know what search helps it has to use, and doesn't force me to manually build a VALUE_SET to be bound on the single attributes? There are many tables, with many fields, and maintaining this solution would be very costly.

I have checked with method GET_ATTRIBUTE_VALUEHELP_TYPE of interface IF_WD_CONTEXT_NODE_INFO, on an attribute which i know to have a search help (Foreign key of a check table).
The method returns 'N', that is the constant IF_WD_VALUE_HELP_HANDLER~CO_VH_TYPE_NO_HELP. So, the framework was not able to find a suitable search help.
Using method GET_ATTRIBUTE_VALUE_HELP of the same interface, on the same attribute, returns me '111', which is constant C_VALUE_HELP_MODE-AUTOMATIC.
Therefore, the WD framework knows it has to automatically detect a value help, but fails to find one.
Also, this means in my opinion that the ALV and the dynamic external mapping are not the culprits: since node creation, no help is detected for any attribute but the date. Honestly, I don't have a clue on what's happening.

Help with static and non static references

Hi all,
I'm new to Java I'm having some difficulties with accessing non static methods.
I'm working with Tree data structures and all the interfaces and methods are non-static.
I have to write a tester main method to create and modify trees but how do I access the non static fields from main which is static?
Any help would be appreciated
Thanks.

Create an Instance for that particular class then call the method using that instance.

Nested interfaces and abstract methods

Consider the following design:
interface ZIF_INTERFACE_A.
methods METHOD_A.
endinterface.
interface ZIF_INTERFACE_B.
interfaces ZIF_INTERFACE_A.
methods METHOD_B.
endinterface.
class CLASS_A_B definition abstract.
public section.
interfaces ZIF_INTERFACE_B
    abstract methods METHOD_B.
interfaces ZIF_INTERFACE_A
    abstract methods METHOD_A.
methods METHOD_C.
endclass.
class CLASS_A_B implementation.
method METHOD_C.
endmethod.
endclass.
When trying to implement this design, the syntax check is giving me an error:
The method "METHOD_A" was declared as not ABSTRACT in a previous INTERFACES statement.
If I implement the design with Java (either using a public nested interface, or using interface inheritance) there is no problem declaring both the methods METHOD_A and METHOD_B as abstract in the CLASS_A_B class.
So it seems to me this might be a bug in the ABAP Objects implementation. Or perhaps I am missing something else here? Does anyone have any suggestions?

Hello,
Nested interfaces
When you include an IF in another IF both of them will exist on the same level, there is no concept of hierarchy. So when you add interface ZIF_B in the implementing class ZCL_A_B, the interface ZIF_A is also "included" in the relationship with the class ZCL_A_B implicitly.
Just try to activate the code below & you'll get the error: "Implementation missing for method zif_interface_a~method_a":
CLASS class_a_b DEFINITION ABSTRACT.
PUBLIC SECTION.
*    INTERFACES zif_interface_a
*      ABSTRACT METHODS method_a.
    INTERFACES zif_interface_b
      ABSTRACT METHODS: method_b.
    METHODS method_c.
ENDCLASS.                    "CLASS_A_B DEFINITION
CLASS class_a_b DEFINITION ABSTRACT.
PUBLIC SECTION.
    INTERFACES zif_interface_b
      ABSTRACT METHODS method_b.
    INTERFACES zif_interface_a
      ABSTRACT METHODS method_a.
    METHODS method_c.
ENDCLASS.                    "CLASS_A_B DEFINITION
So when the compiler is trying to compile your code it encounter implementation of ZIF_INTERFACE_B it finds that the "included interface" method ZIF_INTERFACE_Amethod_a is not abstract. So when you declare ZIF_INTERFACE_Amethod_a as "abstract" in the next line the compiler throws this error.
So you need to define ZIF_INTERFACE_A~method_a as abstract, before defining ZIF_INTERFACE_B. Like this:
CLASS class_a_b DEFINITION ABSTRACT.
PUBLIC SECTION.
    INTERFACES zif_interface_a
      ABSTRACT METHODS method_a.
    INTERFACES zif_interface_b
      ABSTRACT METHODS method_b.
    METHODS method_c.
ENDCLASS.                    "CLASS_A_B DEFINITION
In this case the compiler treats method_a as abstract while checking ZIF_INTERFACE_B. Hence it doesn't throw any error.
Hope i'm clear.
BR,
Suhas
PS: Whenever i face any problem while creating local classes, i create a dummy class in the class builder to check

Help with treemap and other stuff

hi guys..
i m new to this forum..
and this is my first post....so if i act a little naive .....please bare with me.
and if this is not the correct place to post ..i m sorry for that.
i have an assignment to submit....i m getting the whole picture ....but not sure how to go about implementing it.
here it is...
Write an Object Oriented solution to the problem in Java. The solution is to consist of:
A TableIndex class
A TableNavigator Interface
A data row class ....class that i have to create.
An application class to use and test your TableIndex class
The following UML class diagrams show the public methods of the classes. Other methods may be specified. Specify data members, inner classes and interfaces as appropriate.
TableIndex Class
The TableIndex class is an index to a collection of objects. The class is to approximate an index to a data table in memory that consists of a number of rows. To control access to the index a current row is defined that specifies the row that can be accessed. To retrieve a row from the index it must be the current row. The get() method is the only method in TableIndex class that retrieves a row from the index. The current row can be changed explicitly using the methods: previous(), next(), first(), last(), gotoBookmark and find(K); and implicitly using insert(K, V), modify(K, V) and remove().
The TableIndex class is to be implemented using the java API's TreeMap class and must use Generics. The data types K and V below are generic types for the Key and Value (row) respectively. An important aspect of the assignment is using the Java API documentation to understand the TreeMap class.
guys ....can u plz help with the starting bit ..
what should be the opening statement of the class...
public class TableIndex<K , V> .....????
and what should be the treemap declaration..??
TreeMap<K , V> indexTable = new TreeMap<K , V>();...???
i m confused....
can u plz explain to me..

hi mate.....didnt quite get you..
can u plz be a bit more simple in explanation..!!!
i will post the whole question ..so that anyone reading will understand better....
Problem Description
You are to develop an index class and associated classes.
Requirements
Write an Object Oriented solution to the problem in Java. The solution is to consist of:
A TableIndex class
A TableNavigator Interface
A data row class
An application class to use and test your TableIndex class
The following UML class diagrams show the public methods of the classes. Other methods may be specified. Specify data members, inner classes and interfaces as appropriate.
TableIndex Class
The TableIndex class is an index to a collection of objects. The class is to approximate an index to a data table in memory that consists of a number of rows. To control access to the index a current row is defined that specifies the row that can be accessed. To retrieve a row from the index it must be the current row. The get() method is the only method in TableIndex class that retrieves a row from the index. The current row can be changed explicitly using the methods: previous(), next(), first(), last(), gotoBookmark and find(K); and implicitly using insert(K, V), modify(K, V) and remove().
The TableIndex class is to be implemented using the java API's TreeMap class and must use Generics. The data types K and V below are generic types for the Key and Value (row) respectively. An important aspect of the assignment is using the Java API documentation to understand the TreeMap class.
TableIndex
+TableIndex()
+TableIndex(name: String, comp: Comparator)
+getName(): String
+isEmpty(): Boolean
+size(): Integer
+hasPrevious(): Boolean
+hasNext(): Boolean
+previous()
+next()
+first()
+last()
+setBookmark(): Boolean
+clearBookmark()
+gotoBookmark(): Boolean
+contains(key: K): Boolean
+find(key: K): Boolean
+get(): V
+insert(key:K, value: V): Boolean
+modify(value: V): Boolean
+modify(key: K, value: V): Boolean
+remove(): V
+iterator(): Iterator
+equals(obj2: Object): Boolean
+toString(): String
Additional Notes:
The table index has an order defined by the compareTo method of the key's class or by the compare method specified in the class that implements the Comparator interface.
getName(): the name of the index, blank by default.
isEmpty(): returns true if there aren't any rows in the table index
size(): returns the number of rows in the table index
hasPrevious(): returns true if there is a row before the current row.
hasNext(): returns true if there is a row after the current row in sequence.
previous(): if there is a row before the current row, move to the row and make it the new current row.
next() if there is a row after the current row, move to the row and make it the new current row.
first(): if the table isn't empty, move to the first row and make it the new current row.
last(): if the table isn't empty, move to the last row and make it the new current row.
setBookmark(): sets a bookmark at the current row. If the bookmark is successfully set the method returns true. The bookmark is cleared if the TableIndex is empty or the row the bookmark was set on is deleted..
clearBookmark(): sets the bookmark to null, indicating there isn't a bookmark.
gotoBookmark(): if a bookmark has been set, go to the bookmarked row. If successful the book marked row becomes the current row and the method returns true.
contains(K): return true if a row with the key specified exists.
find(K): if a row is found with the specified key, the current row is set to the row found.
get(): returns the current row. Null is returned if there isn't a current row.
insert(K, V): inserts a row (value) with the key specified. The key must not be null and must be unique (not already in the TableIndex). The row (value) must not be null. If the row is successfully inserted true is returned, and the row becomes the current row..
modify(V): change the current row's data to the row (value) specified. The key and the current row key are to remain the same. If successful true is returned.
modify(K, V): change the current row's key and data to the key and row (value) specified. If successful the changed row becomes the new current row. If successful true is returned. Note: this is more difficult than modify(V).
remove(): remove the current row. When a row is deleted the next row (if available) becomes the current row, otherwise if there isn't a next row the previous row becomes the current row, otherwise the table is empty therefore the current row is null.
iterator(): returns an iterator to the rows (values) in the index. The rows are to be retrieved in order. The remove method does not need to be implemented (its method body can be empty)..
the equals method uses the name, and the rows (values) in order when testing for equality.
the toString method should return appropriately formatted data members and the rows (values/data) in the index.
TableNavigator Interface
«interface»
TableNavigator
+isEmpty(): Boolean
+hasPrevious(): Boolean
+hasNext(): Boolean
+previous()
+next()
+first()
+last()
+contains(key: K): Boolean
+find(key: K): Boolean
Additional Notes:
The TableIndex class implements the TableNavigator Interface.
The purpose of the above methods is outlined in the TableIndex class.
Your Data Row Class
You are to include a class of your own to represent a row of data in the TableIndex. This is not to be a class that was covered in other programming subjects. It does not need to be complex but must include a range of data types. This class will be used to test your TableIndex class. The class should have an appropriate name and deal with something of interest to you.
Your Application Class
The application class is to make use of the TableIndex class and your data row class. It is to clearly show how the TableIndex class is used, and in doing so, test it. The class should have an appropriate name. The application class should create two indexes of different key data types. One of the indexes must make use of the Comparator interface to have a key that is in descending order.
Output
Output in the test classes/programs is to go to standard out or a text file. There should be no output from the TableIndex class or your data row class. A GUI interface is NOT required. There is no need to input data from the keyboard or file. Use the Unix script command or write output to a text file (etc) to provide example runs of your test programs.

Help with TYPE and LIKE statements

HI guys,
I know this is really novice stuff, but I am a little confused.
Can anyone please explain the exact difference between TYPE and like with the help of a program, to understand it.
What situation would demand the use of each of the LIKE statement, since I can do all these things using the TYPE ?

Hi Akhil,
I summarized the info in SDN posts and SAP Help, to make it easier for you to understand. I also included some code snippets. Hope these prove to be helpful to you.
The following is from SAP Help:
The Additions TYPE and LIKE
The additions TYPE type and LIKE dobj are used in various ABAP statements. The additions can have various meanings, depending on the syntax and context.
·        Definition of local types in a program
·        Declaration of data objects
·        Dynamic creation of data objects
·        Specification of the type of formal parameters in subroutines
·        Specification of the type of formal parameters in methods
·        Specification of the type of field symbols
A known data type can be any of the following:
·        A predefined ABAP type to which you refer using the TYPE addition
·        An existing local data type in the program to which you refer using the TYPE addition
·        The data type of a local data object in the program to which you refer using the LIKE addition
·        A data type in the ABAP Dictionary to which you refer using the TYPE addition. To ensure compatibility with earlier releases, it is still possible to use the LIKE addition to refer to database tables and flat structures in the ABAP Dictionary. However, you should use the TYPE addition in new programs.
The LIKE addition takes its technical attributes from a visible data object. As a rule, you can use LIKE to refer to any object that has been declared using DATA or a similar statement, and is visible in the current context. The data object only has to have been declared. It is irrelevant whether the data object already exists in memory when you make the LIKE reference.
·        In principle, the local data objects in the same program are visible. As with local data types, there is a difference between local data objects in procedures and global data objects. Data objects defined in a procedure obscure other objects with the same name that are declared in the global declarations of the program.
·        You can also refer to the data objects of other visible ABAP programs. These might be, for example, the visible attributes of global classes in class pools. If a global class cl_lobal has a public instance attribute or static attribute attr, you can refer to it as follows in any ABAP program:
DATA dref TYPE REF TO cl_global.
DATA: f1 LIKE cl_global=>attr,
       f2 LIKE dref->attr.
You can access the technical properties of an instance attribute using the class name and a reference variable without first having to create an object. The properties of the attributes of a class are not instance-specific and belong to the static properties of the class.
Example
TYPES: BEGIN OF struct,
         number_1 TYPE i,
         number_2 TYPE p DECIMALS 2,
       END OF struct.
DATA: wa_struct TYPE struct,
       number    LIKE wa_struct-number_2,
       date      LIKE sy-datum,
       time      TYPE t,
       text      TYPE string,
       company   TYPE s_carr_id.
This example declares variables with reference to the internal type STRUCT in the program, a component of an existing data object wa_struct, the predefined data object SY-DATUM, the predefined ABAP type t and STRING, and the data element S_CARR_ID from the ABAP Dictionary.
The following info is from various posts:
--> Type: It is used when userdefined object link with SAP system data type.
Local types mask global types that have the same names. When typing the interface parameters or field symbols, a reference is also possible to generic types ANY, ANY TABLE,INDEX TABLE, TABLE or STANDARD TABLE, SORTED TABLE and HASHED TABLE.
--> Like: It is when data object link with the other data object.
--> TYPE, you assign datatype directly to the data object while declaring.
--> LIKE,you assign the datatype of another object to the declaring data object. The datatype is referenced indirectly.
you can refer to all visible data objects at the ABAP program's positon in question. Only the declaration of the data object must be known. In this case it is totally irrelevant whether the data object already exists physically in
memory during the LIKE reference. Local data objects mask global data objects that have the same name.
--> Type is a keyword used to refer to a data type whereas Like is a keyword used to copy the existing properties of already existing data object.
Types: var1(20) type c.
data: var2 type var1. ( type is used bcoz var1 is defined with TYPES and it
does not occupy any memory spce.
data: var3 like var2. ( like is used here bcoz var2 is defined with DATA
so it does occupy space in memory ).
data: material like mara-matnr. ( like is used here bcoz mara-matnr is stored in memory)
--> Type refers the existing data type
--> Like refers the existing data object
Please Reward Points if any of the above points are helpful to you.
Regards,
Kalyan Chakravarthy

Interface and Abstract class difference

An interface can be used in such a way that we don't know the class of object assigned to a reference of that interface type until runtime. Can we use the abstract class in a similar way too?
The difference between an abstract class and interface can be listed as
1. Interface can not have implementation of any method
2. The usage of interface and class is one other difference
3. What other differences we have?

Yes an abstract class can be used in a similar way. The main issue with an abstract class is that you extend it and you can only extend one class so that can be a huge limitation that an interface does not give you.
Here's another one that is often overlooked: use both.
public abstract class SomeBaseClass implements Runnable {
public abstract void someAbstractMethod();
public void someMethodWithADefaultImplementation(){
System.out.println("Hello!");
}Any class that extends SomeBaseClass (and is not abstract) will need to implement the run() method of the Runnable interface.

Interfaces and abstract classes

can anyone pls tell me where exactly an abstract class is used and where exactly an interface is to be used.
i think the main difference between an abstract class and an interface is that an interface will have all the abstract methods whereas an abstract class can have one or more abstract methods--- if i am not wrong.
anything to add? -- pls let me know on this....
and also how they might be useful for us....

Inheritance is the most popular feature of the OOP. By organising classes into class hierachy it gives an extra dimension to the encapsulation of abstract data types becauase it enables classes to inherit attributes/methods from other classes.
There are two complementary roles of inheritance in OOP application.
1. Specialisation: Extending the functionality of an existing class.
2. Generalisation: Sharing commonality between two or more classes.
So adding functionality by extending what exists at each level to create more specialized classes. This would create a hierarchy and would be helpful even later on in maintenance.
Now when to have an abstarct class and when an interface. An interface just defines the basic functionality to be implemented by all the subclasses, though the way they are implemented may be different. e.g an interfaca animal can have all those functionalities common to all animals in basics but different in implementation. e.g all animals walk however some walk on two legs and some on four. All animals can see but they might have a different colour spectrum visible. So all such methods general but common can be in an interface.
Abstract classes come into play at a more defined level e.g in an abstract class human though walk would be the same so implemented there and then but talking can be left abstract since there may be different languages involved.
For more details refer to a good OOP book.

Help with interface and abstract

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