Regarding implementations of interfaces

In Collection framework API, all the interfaces have been provided with adapter classes, which provide most of the skeletal implementation for those interfaces. The classes which are extended from these adapter classes are again implementing all the super interfaces. Why? For what reason, the ArrayList, HashSet etc., are implementing the interfaces List, Collection & Set, Collection respectively.

Perhaps the list of interfaces isn't stored in plain text, but for a small class that extends ArrayList I see this:.......1........
<init>...()V...C
ode...LineNumber
Table...main...(
[Ljava/lang/Stri
ng;)V...SourceFi
le...deleteme.ja
va........java/u
til/Vector...del
eteme$1CustomCla
ss...CustomClass
...InnerClasses.
............My n
ame is Gary...de
leteme...java/ut
il/ArrayList...(
Ldeleteme;)V...a
dd...(Ljava/lang
/Object;)Z.!....
..............D.
..........Y...M.
..Y*...N,-...W..
.............II don't see all the interfaces listed in the class file itself. Maybe I don't know what I'm talking about, but I'm sure I don't know what you're talking about. Perhaps your decompiler is looking up the inheritence tree.
I effect, the real class ArrayList DOES implement interface List. I don't understand the problem.

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How to implement XI interfaces in online and offline modes?

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Hi,
Are you looking for Push and Pull mechanism of PI?
When the adapters like SOAP, HTTP, IDOC, etc. send the data to PI , it is nothing but a push mechanism, and hence the communication is synchronous by default.
But adapters like JDBC, File, etc. they fetch the data from Source Applications, so it is a kind of Pull mechanism for PI, and
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Actual implementation of interfaces involved in JDBC connection creation

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Hi sharma,
JDBC API will be implemented by JDBC Driver vendors. For example Microsoft provide "com.microsoft.jdbc.sqlserver.SQLServerDriver" driver for SQL Server 2000. Similarly Oracle privide several JDBC Drivers to be used with Oracle databases.
Sun has provided a JDBC-ODBC bridge (Driver) along with its JDK or JSDK. This driver is capable for connecting Java applications with any ODBC connection.
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How to find out in program which all classes have implemented an interface

Hello,
I have created an interface and few classes are implementing the interface.
I want to know in a program which all class have implemented the interface.
Is it possible to find it out and how?
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Hi Bikash,
Read the Database view VSEOIMPLEM with where condition REFCLSNAME = Interface Name and version = 1.
This would give you all the classes which have implemented the interface and are active...
If you want to look at the values that the field version can have then see Type Group SEOC ans search for version....
Hope this help...
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How to get classes which implement the interface in program

Hi,
I created an interface and some classes are implementing it. I want to know in which classes the interface is implemented through program. I mean in which table the interface implemented details stores.
please helps regarding this.
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Priya

Hi.,
Read the database view VSEOIMPLEM with where condition., REFCLSNAME = <Interface Name> and Version = 1.
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hope this helps u.,
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Hi SAP Gurus & Mr Uwe,
I'm interested with your discussion (Mr Uwe's commented) a while ago regarding dummy implementation of interface on Mar 25, 2008 12:52 PM.
I saw this CL_EX_CRM_BUS20001_R3A class of mine has the same code as the topic that you commented.
I would like to know about this dummy implementation of interface. Firstly is what is the use of this interface? I assume that this program is the main BADI so it should have all the parameters required for the next program which is in this case is the interface. Is that right?
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Hi Adrian,
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Concrete classes implement abstract class and implements the interface

I have one query..
In java collection framework, concrete classes extend the abstract classes and implement the interface. What is the reason behind extending the class and implementing the interface when the abstract class actually claims to implement that interface?
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Why do you post this question again? You already asked this once in another thread and it has been extensively debated in that thread: http://forum.java.sun.com/thread.jsp?forum=31&thread=347682

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I am studying some code that I need to understand well. This code works, I just don't understand the following:
A class was defined extending an interface as so:
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Can someone explain?When a class implements an interface, or extends another class, or when a interface extends another interface, it means that anywhere an instance of the parent class or interface is expected, the child can be used.
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If you say "give me some food," and you don't specify anything else, the person you're talking to can hand you a hamburger or an apple or a bowl of rice. Any of those will meet the requirements you put forth.
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When we do a program that deals with database connectivity,we are not implementing the Interfaces like Statement,ResultSet.But we are using those
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Thanks in advance

The DB vendors are responsible for providing implementation classes for these interfaces. That's why we need to keep DB specific jar files in CLASSPATH when we do DB activities..
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Hi all,
I came across the one question.
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Its the same amount of programming work...
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http://developerlife.com/lessons/threadsintro/default.htm#Implementing

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Sorry, but there is no BaseCommand interface in the API.
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Implementing comboboxmodel interface

If i was to implement this interface there is this method definition:
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[email protected]

Must implement specifik interface

Hi,
Im creating a game to force myshelf to code a game-engine, just for fun. In this game I have superclass for a basic unit. This class gets subclassed down to game-units. I have different type of game units, some more advanced than others (my game idea is like a manager game where choose between units similar to warcraft 3 units).
To help the game-engine separate between the different type of units and the methods that can be used on them, I want to use differtent interface for the advanced units. This could be the start of the Wizard-class:
public class Wizards extends BasicUnit implements SpellCaster {
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}Question is: How can I force a method in the game-enginge class to look if a used unit implements a certain interface, in this case the SpellCaster-interface?
I know it should be possible, like the Comparable Interface. But how do i do it?
If its a dumb question a link to the specifik documents would do, I read it myshelf. But of course I would be happy if someone have the kindness to write an example. Again, this aint homework, just a fun x-mas project for me.

Ani_Skywalker wrote:
Hi again Jverd,
I google [visitor pattern|http://en.wikipedia.org/wiki/Visitor_pattern] and through that I also find [virtual function|http://en.wikipedia.org/wiki/Virtual_functions] . I can see how its usefull in this issue.
Thought my main concern for the moment is about [composition over inheritance|http://blogs.msdn.com/steverowe/archive/2008/04/28/prefer-composition-over-inheritance.aspxI]. This is not what we learned in school when I took my first and second java courses. But I think the composition over inheritance strategy seems very sensible.
jverd wrote:
I don't really know your whole picture, but one option is to define a type that has those particular operations in common, and pass that type around when that's what you need. The subclasses could inherit from a base class that provides those, or implement an interface, and then add their own methods.But this is exactly what my class BasicUnit does. Maybe my english is bad and I misslead you, or maybe I should pick a better name for that class, like Unit. But what it does is to hold methods that every unit in the game use. Subclasses that need more methods adds that. The way you wrote your example is kind of how I've done it, as it seems to me. Could you tell me were you think I do wrong?It may have just been a misunderstanding on my part, as I don't know you and I don't know your requirements or the details of how you're implementing them.
Or it may be that you're kind of close to doing it correctly, but not quite. The situation I described as a good approach can look a lot like the not-so-good way I thought you were doing it. I'm kind of sleep-deprived right now, so I don't have the energy or brainpower to go into any more detail at the moment.
Good luck though. I expect somebody will continue helping you if you keep working at it.

Regarding implementations of interfaces

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