Question of i++ and interface

i want ask what is the difference bewteen I++ and ++i ?
what is the difference bewteen interface and extend a class?

i want ask what is the difference bewteen I++ and ++i?Try this and you may get some idea
i = 5;
System.out.println(++i);
i = 5;
System.out.println(i++);

Similar Messages

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

Question about Classes, Abstract Classes and Interfaces.

I have been experimenting with Classes, Abstract Classes and Interfaces and wonder if anyone can explain this to me.
I was looking for a way to assign a value to a variable and then keep it fixed for the session and have devised this.
First I create an abstract class like this:
public abstract class DatabaseConnection {
private static String ServerName = null;
public static void setServerName(String serverName) {
          ServerName = serverName;
     public static String getServerName() {
          return ServerName;
}and then I created an interface
public interface DatabaseAccess {
     String servername = DatabaseConnection.getServerName();
}And finally the class itself with some test lines in it so I could see what was going on:
public class CreateDatabase extends DatabaseConnection implements DatabaseAccess {
     public static void main (String args[]){
          new CreateDatabase();
     public CreateDatabase(){
          setServerName("Server Name 1");
          System.out.println ("Before update ");
          System.out.println ("ServerName from Interface           = " + servername);
          System.out.println ("ServerName from Abstract Class = " + getServerName());
          System.out.println ("After update ");
          setServerName("Server Name 2");
          System.out.println ("ServerName from Interface           = " + servername);
          System.out.println ("ServerName from Abstract Class = " + getServerName());
          System.out.println ("==========================");
}The output I get from the above is:
Before update
ServerName from Interface           = Server Name 1
ServerName from Abstract Class = Server Name 1
After update
ServerName from Interface           = Server Name 1
ServerName from Abstract Class = Server Name 2
==========================I also tried this in another class which calls the above class to see if I get the same effect
public class CheckDatabaseAccess {
     public static void main (String args[]){
          new CreateDatabase();
          CreateDatabase.setServerName("Server 3");
          System.out.println("CreateDatabase "+CreateDatabase.servername);
          CreateDatabase.setServerName("Server 4");
          System.out.println("CreateDatabase "+CreateDatabase.servername);
          CreateDatabase.setServerName("Server 5");
          System.out.println("CreateDatabase "+CreateDatabase.servername);
}The output of which is this:
Before update
ServerName from Interface           = Server Name 1
ServerName from Abstract Class = Server Name 1
After update
ServerName from Interface           = Server Name 1
ServerName from Abstract Class = Server Name 2
==========================
CreateDatabase Server Name 1
CreateDatabase Server Name 1
CreateDatabase Server Name 1Can anyone explain why I appear to only be able to change or set the ServerName only the once?
Is this the correct way to do it? If it is it's exactly what I am looking for, a way to set the value of variable once in a session and then prevent it being changed.
Or is there a better way of doing this.
What I want to use this for is for example, storing the accesses to a database on a server. I won't know what server the database will be stored on nor what the database is called so I create an INI file which stores this information in encrypted format, which is set by the database administrator. It occurs to me I can use this method to then retrieve that data once and once only from the INI file and use that throughout the life of the session to access the database.
Any help appreciated
Regards
John

Not gonna read all of it, but this jumps out:
public abstract class DatabaseConnection {
private static String ServerName = null;
public interface DatabaseAccess {
     String servername = DatabaseConnection.getServerName();
}You have two completely separate variables (with two different names, for that matter, since you were inconsistent in your capitalization, but it wouldn't make a difference if they did have the same name with the same case). And the one in the interface is implicitly public, static, and final.
Anytime you refer to "servername" through a reference of type DatabaseAccess, it refers to the one declared in the interface.
Anytime you refer to "ServerName" inside the DatabaseConnection class, it refers to the one declared in that class.

A question about grub and USB

Hi All
I have a quick question about grub and USB that I can't quite find the answer to by searching. Most of the FAQs discuss booting a full linux dristribution from USB. My situation is this. I am getting a new computer with two drives, the second will be arch and the first will be Vista (for my wife). I want the computer to boot the same way that my wife's machine boots at work so I don't want to install grub on the MBR. So, is there a way to have all of the grub config files and kernels installed on the second drive and simply install to grub boot loader to the MBR of a USB stick? My goal would be to simply plug the USB stick into the new PC and boot arch from the second drive.
Thanks
Kev

i cant say for hp's
havent worked on any in a while
recent machines have been coupleof dell's , vaio & emachine
which dells do offer it at least the ones i tried , my laptop does(dell)
all home pc's are built by me which do offer to boot individual drives
what hp you getting it may tell in specs
are both discs sata? if so it might not offer this option with 2 drives of same interface
check your power supply alot of these preconfigured machines put cheap under reated power supplies in there
& will burn your motherboard i just replaced PS(250 watt) & mobo(845gvsr) in an emachines <cheap stuff<
i hope you researched the pc before buying ie : mobo, power supply are the biggest concerns
i find it much more benificial to build my own machine gives me peace at mind. the cost is sometimes more in $ but not always , your biggest expense is time researching hardware
if you live in usa the best places to start looking are bensbargains.net & pricewatch.com
i am not affiliated with either & niether sell the hardware they are just advertisers a place to buy
for costomized machines that i would trust is unitedmicro.com theyll asemble & test before shipping
i have gotten 2 machines so far from them with NO PROBLEMS with hardware (knock knock)
you may want to consider this in your next venture for pc

Oracle EBS Based and Interface tables

Hi,
Where can I find the list of all Based and Interface tables used in Oracle EBS R12 Applications. OM, INV, AR, AP, GL, & PO (Purchasing).
I have been told that they are available in "My Oracle Support" please send me the path.
Thanks,
Amorsolo.

Please see old threads, it should answer your question -- http://forums.oracle.com/forums/search.jspa?threadID=&q=Interface+AND+Tables&objID=c3&dateRange=all&userID=&numResults=15&rankBy=10001
Thanks,
Hussein

A question about inheritance and overwriting

Hello,
My question is a bit complicated, so let's first explain the situation with a little pseudo code:
class A {...}
class B extends A{...}
class C extends B {...}
class D extends C {...}
class E extends B {...}
class F {
ArrayList objects; // contains only objects of classes A to E
void updateObjects() {
    for(int i = 0; i < objects.size(); i++)
      A object = (A) objects.get(i); // A as superclass
     update(A);
void update(A object) { ... }
void update(B object) { ... }
void update(D object) { ... }
}My question now:
For all objects in the objects list the update(? object) method is called. Is it now called with parameter class A each time because the object was casted to A before, or is Java looking for the best fitting routine depending on the objects real class?
Regards,
Kai

Why extends is evil
Improve your code by replacing concrete base classes with interfaces
Summary
Most good designers avoid implementation inheritance (the extends relationship) like the plague. As much as 80 percent of your code should be written entirely in terms of interfaces, not concrete base classes. The Gang of Four Design Patterns book, in fact, is largely about how to replace implementation inheritance with interface inheritance. This article describes why designers have such odd beliefs. (2,300 words; August 1, 2003)
By Allen Holub
http://www.javaworld.com/javaworld/jw-08-2003/jw-0801-toolbox.html
Reveal the magic behind subtype polymorphism
Behold polymorphism from a type-oriented point of view
http://www.javaworld.com/javaworld/jw-04-2001/jw-0413-polymorph_p.html
Summary
Java developers all too often associate the term polymorphism with an object's ability to magically execute correct method behavior at appropriate points in a program. That behavior is usually associated with overriding inherited class method implementations. However, a careful examination of polymorphism demystifies the magic and reveals that polymorphic behavior is best understood in terms of type, rather than as dependent on overriding implementation inheritance. That understanding allows developers to fully take advantage of polymorphism. (3,600 words) By Wm. Paul Rogers
multiple inheritance and interfaces
http://www.javaworld.com/javaqa/2002-07/02-qa-0719-multinheritance.html
http://java.sun.com/docs/books/tutorial/java/interpack/interfaceDef.html
http://www.artima.com/intv/abcs.html
http://www.artima.com/designtechniques/interfaces.html
http://www.javaworld.com/javaqa/2001-03/02-qa-0323-diamond_p.html
http://csis.pace.edu/~bergin/patterns/multipleinheritance.html
http://www.cs.rice.edu/~cork/teachjava/2002/notes/current/node48.html
http://www.cyberdyne-object-sys.com/oofaq2/DynInh.htm
http://www.gotw.ca/gotw/037.htm
http://www.javajunkies.org/index.pl?lastnode_id=2826&node_id=2842
http://saloon.javaranch.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic&f=1&t=001588
http://pbl.cc.gatech.edu/cs170/75
Downcasting and run-time
http://www.codeguru.com/java/tij/tij0083.shtml
type identification
Since you lose the specific type information via an upcast (moving up the inheritance hierarchy), it makes sense that to retrieve the type information ? that is, to move back down the inheritance hierarchy ? you use a downcast. However, you know an upcast is always safe; the base class cannot have a bigger interface than the derived class, therefore every message you send through the base class interface is guaranteed to be accepted. But with a downcast, you don?t really know that a shape (for example) is actually a circle. It could instead be a triangle or square or some other type.
To solve this problem there must be some way to guarantee that a downcast is correct, so you won?t accidentally cast to the wrong type and then send a message that the object can?t accept. This would be quite unsafe.
In some languages (like C++) you must perform a special operation in order to get a type-safe downcast, but in Java every cast is checked! So even though it looks like you?re just performing an ordinary parenthesized cast, at run time this cast is checked to ensure that it is in fact the type you think it is. If it isn?t, you get a ClassCastException. This act of checking types at run time is called run-time type identification (RTTI). The following example demonstrates the behavior of RTTI:
//: RTTI.java
// Downcasting & Run-Time Type
// Identification (RTTI)
import java.util.*;
class Useful {
public void f() {}
public void g() {}
class MoreUseful extends Useful {
public void f() {}
public void g() {}
public void u() {}
public void v() {}
public void w() {}
public class RTTI {
public static void main(String[] args) {
Useful[] x = {
new Useful(),
new MoreUseful()
x[0].f();
x[1].g();
// Compile-time: method not found in Useful:
//! x[1].u();
((MoreUseful)x[1]).u(); // Downcast/RTTI
((MoreUseful)x[0]).u(); // Exception thrown
} ///:~
As in the diagram, MoreUseful extends the interface of Useful. But since it?s inherited, it can also be upcast to a Useful. You can see this happening in the initialization of the array x in main( ). Since both objects in the array are of class Useful, you can send the f( ) and g( ) methods to both, and if you try to call u( ) (which exists only in MoreUseful) you?ll get a compile-time error message.
If you want to access the extended interface of a MoreUseful object, you can try to downcast. If it?s the correct type, it will be successful. Otherwise, you?ll get a ClassCastException. You don?t need to write any special code for this exception, since it indicates a programmer error that could happen anywhere in a program.
There?s more to RTTI than a simple cast. For example, there?s a way to see what type you?re dealing with before you try to downcast it. All of Chapter 11 is devoted to the study of different aspects of Java run-time type identification.
One common principle used to determine when inheritence is being applied correctly is the Liskov Substitution Principle (LSP). This states that an instance of a subclass should be substitutible for an instance of the base class in all circumstances. If not, then it is generally inappropriate to use inheritence - or at least not without properly re-distributing responsibilities across your classes.
Another common mistake with inheritence are definitions like Employee and Customer as subclasses of People (or whatever). In these cases, it is generally better to employ the Party-Roll pattern where a Person and an Organization or types of Party and a party can be associated with other entities via separate Role classes of which Employee and Customer are two examples.

Method access$0() and Interfaces doubts

Hello All,
I am working on a class browser, I have created one and it works successfully to a certain extent. But The class which I am having a Demo for a Tree Implementation in GUI, has a method called access$0() which I guess is automatically created on runtime by the super classes or somewhere, please let me know how and where can I get more details about this method.
Also If my class under inspection is implementing one or more interfaces, how can I access its method names and variables.
Also One more question, does Java maintain a list of sub-class information for each class somewhere.. just like Small Talk or it doesn't?? Please explain.
Thanks,
Sirish

access$ methods are widely used to access private
members of enclosing class from its inner class and
vice-versa. These methods are generated by Java
compiler, not by JVM runtime.
See
http://java.sun.com/docs/books/jvms/second_edition/htm
l/ClassFile.doc.html#80128 for more details about
synthetic class members.
Other questions need more clarification.I will check that link, Regarding the other two questions:
2. What I meant in my interfaces question is that... Say I have a class X that Extends Y and implements A,B
Then if I want to display all the methods and fields of these classes and interfaces in a recursive way, till I reach the Object class, by going to superclass every time, then I understand I can get to class Y simple by
using x.getSuperClass()
but how can I get the interface methods?? and go upwards in that hierarchy??
3. Sub class question is like this - Say I have 3 classes all user defined in the same directory Class A,B,C where A is the superclass of B and C. My class browser is displaying the hierarchy details of A, then is there any way to put in the details of B and C in the same hierarchical display or just display a separate list of subclass that this class has. I am not sure whether I have made it clear still.
(I didnot understnad your reply on changing the class path, can you please explain it in a bit more detail, provided it holds for this question.)
Regards,
Sirish

Questions for I/O interface experts

I have few questions for I/O interface experts:
I have a Power Mac G5 2.3 Ghz 8GB of RAM, PCI-X slots, and am running Final Cut Studio FC version 6. I currenly have an HD project on my timeline (uploaded directly form a P2 card via 400FW), and I'd like to be able to output on a HD VTR deck as wellas a BetacamSP deck:
1) which AjA Kona cards (3, LHe, LH) is right for me?
2) did you personally experience, or are you aware of any issues with this Kona card and Final Cut version 6? Any tips before I purchase?
3) will this card allow me to output uncompressed HD, that is, the same quality I uploaded?
4) in which of the slots on my back tower does it go? 64bit 100MHz or 64bit 133MHz?
Cheers,
Rinaldo

I think FireWire is probably the best route.
The main difference between the two seem to be that the 1814 has more inputs and the ADAT interface, the 410 has more outputs.
So are you planning on recording, then go for the 1814.
If you envision that 2 mics and 2 inputs is enough for your recording needs and you eventually want to mix surround you'd need the 410 as it is the one with enough outputs.
If you want specific advice about interfaces I suggest you ask in the Logic forums as those users would be most experienced with this aspect of an audio system.

Productionising ODI code and interfaces

I come from a programming background, and there is one aspect of ODI that is confusing me.
When I do development work on ODI, I usually reverse engineer Hyperion Planning, Hyperion Essbase, and some Oracle views which are all also in Development. I build the interfaces, test them and make sure they all work well.
Now, when it comes to moving these interfaces into production, to me, the logical meaning of that processis that the same interface should be hitting the ORacle views, Hyperion Planning/Essbase on the Production servers. So, my question then is how do I do that.
If I have to reverse engineer the planning and essbase models in Production all over again, and re-build the interfaces, its just duplication of work and a waste of time. I looked in the user guide and admin guide, but neither of them were helpful.
Any gurus out there, your help will go a long way and will be very much appreciated!!
Thanks

You're not far from where you want to get. If the structures in DEV and PROD are identical, then you don't have to worry about creating models and interfaces in PROD. ODI takes care of this through its layered architecture of Logical and Physical schemas which are linked via Contexts.
Here are some guidelines...
In Topology Manager:
- Create your PROD servers and physical schemas
- If your Master Repository for PROD is on a different server than for DEV, then create the Logical schemas with the same names that you have in DEV
- Create a PROD context and assign each logical schema to the corresponding physical schema
- Set up your PROD Work Repository as an Execution Repository (there is an option when you create the repository
(It is very important that the names are identical in PROD and DEV, the so called CODES are what links Master and Work Repositories)
In DEV Designer:
- Generate scenarios from the integration processes you want to migrate
- Export the scenarios to XML
In PROD Operator (PROD Designer is not available as it is an execution repository which is readonly - except for variables):
- Import the scenarios
- Launch the scenarios to test everything is working.
Hope this helps.
Regards,
Matt

Second HDD bracket and interface cable for DV7 3110ea

I apologize if this has already been covered on here.
I need a hard drive bracket and interface cable to fit a second SATA HDD. I think the HP part numbers are 611935-001 for the interface and 532591-001 for the bracket.
Can anyone confirm this and possibly suggest somewhere I could get them from as the HP partmaster site was not much help.
I have found a few online suppliers of these parts and the prices vary from around £22 to £35 each. I would like to be sure they are the correct parts before ordering them.
This question was solved.
View Solution.

I got the hard drive caddy from here http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=220690235689 They do appear to have more in stock and cost a lot less than other online suppliers I tried.
The connector was from here http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=260730251819

Difference between abstract classes and interfaces

I actually wonder about what are the differences between abstract classes and interfaces may somebody give an example code about it?
and i have one more question how can i use interfaces like multiple inheritance ? i mean when i implement an interface like
class a extends b implements c,di have to use all c and d methods but what that methods means?
I mean as i know we cannot make implementations of methods in interfaces
but for example in runnable interface there is a method like run() and it has been defined somewhere because it knows what to do(i mean when it will run), i just write my code into that method .

Once you get past the starting point (I am referring to the OP here), there are a few salient differences:
You can only extend (or generalize) a single superclass; however, you can implement (or realize) multiple interfaces. As such, all things being equal, using an interface in lieu of an abstract class 'frees' your design. Later, if you want the implementor of an interface to inherit from another class, there is not issue.
Any abstract method specifies a contract. However, abstract classes allow you to also add common behavior to subclasses. This is an overused justification for abstract classes, IMO. You can achieve the same effect using delegation and still having interfaces.
Always program to interfaces wherever possible. This means that you define an interface and have an implementing class (usually at a minimum). Do not do this for all your classes, but rather the ones that make your system unique (the domain model or M in MVC architecture). This allows you to later change implementation with a minimal amount of refactoring. This is a core precept from the Group of Four and any number of decent programming books.Best of luck.
- Saish

What happens as we use strictfp modifier with class and interface ?

I just knew that strictfp can't be used with variables?
I want to know that why we use strictfp with class and interface?

makpandian wrote:
i hope i can understand if you explain myself.Okay, let me go ahead and try to explain yourself.
The concept of a makpandian can be summed up as the following: a simple-minded, java forum-goer who posts questions directly from his SCJP 6 study guide in hopes that forum members will give him a simple answer that he can correlate to a multiple-choice response. By doing this, the makpandian suspects that passing the SCJP 6 exam will become a tangible reality, thus enabling it to obtain a job in the public work sector (given the great significance of this type of certification in the makpandian's presumed country of origin (India, for those of you who aren't following along)).
So how'd I do? Did I do a good job of explaining yourself?

Diff b/w msg mapping and interface mapping

hi
i have some doubt's:
1. diff b/w msg mapping and interface mapping
2. What is product in SLD? usually who creates the product,technical,business system??
thx in advance..

hI Smartsoft General User ,
The following r excellent websites on mapping which differentiate msg mapping and interface mapping in detail:
Excellent PDF Document on Mapping
http://help.sap.com/bp_bpmv130/Documentation/Operation/MappingXI30.pdf
Mapping Development with the ABAP Workbench
http://help.sap.com/saphelp_nw04/helpdata/en/10/5abb2d9df242f6a62e22e027a6c382/content.htm
ABAP Mappings
http://help.sap.com/saphelp_nw04/helpdata/en/ba/e18b1a0fc14f1faf884ae50cece51b/content.htm
how to create a flat file out of an IDoc-XML by means of an ABAP mapping program and the J2EE File Adapter.
https://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/docs/library/uuid/46759682-0401-0010-1791-bd1972bc0b8a
How to Use ABAP Mapping in XI 3.0
https://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/docs/library/uuid/e3ead790-0201-0010-64bb-9e4d67a466b4
These r excellent websites in SLD:
How ToHandle the SLD for SAP XI
https://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/docs/library/uuid/9e76e511-0d01-0010-5c9d-9f768d644808
How ToHandle Caches in SAP XI 3.0
https://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/docs/library/uuid/1a69ea11-0d01-0010-fa80-b47a79301290
http://www.sap-press.de/download/dateien/751/sap_press_exchange_infra_engl.pdf
cheers!
gyanaraj
****Pls reward points if u find this helpful

What is diff b/w abstarct and interface

what is diff b/w abstarct and interface in real time where we come across, give a best real time example

I think there have been lots of threads in this forum discussing interfaces and abstract classes.
http://forum.java.sun.com/thread.jspa?forumID=256&threadID=389830
http://forum.java.sun.com/thread.jspa?forumID=54&threadID=5120074
http://forum.java.sun.com/thread.jspa?forumID=54&threadID=499077
http://forum.java.sun.com/thread.jspa?forumID=31&threadID=546668
Interfaces define a contract for what an implementing class should provide. Abstract classes do the same but they can also provide some common part of the implementation.

Question regarding battery and warranty

Hi all! I have a quick question about how and if my warranty applies to my battery. After about a year and a half of ownership (I have the three-year extended warranty), my battery has gone completely down the toilet. It wasn't a problem before, but this year I have to lug my T61p around a lot for lab work. My battery is now rated at... 39.75Wh when it shipped at 84.24Wh. This is a pretty drastic difference. In any case, I don't think that this is covered by warranty, but figured that I'd ask before I drop $180 on a new battery (ouch). And, speaking of, if my suspicions are correct, does anybody know where I might find a 9-cell battery for the T61p? All I'm seeing on Lenovo's website is the one for the N100... which doesn't... match very well. Yaknow.
Thanks a lot!
ThinkPad T61p [June 2008]: 2.5Ghz Penryn Core 2 Duo, 4GB DDR2 RAM, NVidia Quadro FX 570m 256MB, 160GB 7200RPM Fujitsu HDD, 1920x1200 WUXGA Matte LCD, Windows 7 RC1

Is either of these appropriate? I'm wary of the one on Amazon, as there are other (off-brand) batteries that are advertised as being Lenovo ones (though those generally sell for a lower price). The other one just looks like I'll have to call up to buy it.
http://www.amazon.com/Lenovo-43R9255-ThinkPad-Notebook-Battery/dp/B001DX9EKA
http://affordablepcsupply.com/products/IBM/REF/42T4511.html
Thoughts?
ThinkPad T61p [June 2008]: 2.5Ghz Penryn Core 2 Duo, 4GB DDR2 RAM, NVidia Quadro FX 570m 256MB, 160GB 7200RPM Fujitsu HDD, 1920x1200 WUXGA Matte LCD, Windows 7 RC1

Question of i++ and interface

Similar Messages

Maybe you are looking for