Best Practice: Using a static variables and methods vs singleton pattern

Just curious, since when anything, within a class, is denoted as static it typically will be stored in main memory as a class property(method, variables, etc). Is it a good practice to be doing this all the time or is the singleton pattern a better choice. Please explain why. Thanks.

I wouldnot make anything other than the constants and the instance itself static. And I cant think of a reason wjy one would.

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A basic question about static variables and methods

What would be the effects if I declare lots of static variables and static methods in my class?
Would my program run faster?
Would the class take more memory spaces? (If so, how do I estimate an appropriate number of variabls and methods to be declared static?)
Thank you @_@

when you declare a static var the var isn't created for every instance of the class, it just "live" in the class
when you declare a static method is the same, so if you have:
class MyClass
static int myMethod()
//Method work
you dont need to have a instance of the class to call myMethod, you can do such things like this.
int value = Myclass.myMethod();
if myMethod isn't static you can't do this.. so, if
class MyClass
int myMethod()
//Method work
you CAN'T call
int value = MyClass.myMethod();
instead, you have to write
MyClass m;
m = new MyClass();
value = m.myMethod();

Static and non-static variables and methods

Hi all,
There's an excellent thread that outlines very clearly the differences between static and non-static:
http://forum.java.sun.com/thread.jsp?forum=54&thread=374018
But I have to admit, that it still hasn't helped me solve my problem. There's obviously something I haven't yet grasped and if anyone could make it clear to me I would be most grateful.
Bascially, I've got a servlet that instatiates a message system (ie starts it running), or, according to the action passed to it from the form, stops the message system, queries its status (ie finds out if its actually running or not) and, from time to time, writes the message system's progress to the browser.
My skeleton code then looks like this:
public class IMS extends HttpServlet
 public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
 doPost(request, response);
 public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
 //get the various parameters...
 if (user.equalsIgnoreCase(username) && pass.equalsIgnoreCase(password))
 if(action.equalsIgnoreCase("start"))
 try
 IMSRequest imsRequest = new IMSRequest();
 imsRequest.startIMS(response);
 catch(IOException ex)
 catch(ClassNotFoundException ex)
 else if(action.equalsIgnoreCase("stop"))
 try
 StopIMS stopIMS = new StopIMS();
 stopIMS.stop(response);
 catch(IOException ex)
 else if(action.equalsIgnoreCase("status"))
 try
 ViewStatus status = new ViewStatus();
 status.view(response);
 catch(IOException ex)
 else
 response.sendRedirect ("/IMS/wrongPassword.html");
public class IMSRequest
//a whole load of other variables
public PrintWriter out;
 public int messageNumber;
 public int n;
 public boolean status = false; //surely this is a static variable?
 public String messageData = ""; // and perhaps this too?
 public IMSRequest()
 public void startIMS(HttpServletResponse response) throws IOException, ClassNotFoundException
 try
 response.setContentType("text/html");
 out = response.getWriter();
 for(n = 1 ; ; n++ )
 getMessageInstance();
 File file = new File("/Users/damian/Desktop/Test/stop_IMS");
 if (n == 1 && file.exists())
 file.delete();
 else if (file.exists())
 throw new ServletException();
 try
 databaseConnect();
 catch (ClassNotFoundException e)
//here I start to get compile problems, saying I can't access non-static methods from inside a static method
 out.println(FrontPage.displayHeader());
 out.println("</BODY>\n</HTML>");
 out.close();
 Thread.sleep(1000);
 catch (Exception e)
 }OK, so, specifially, my problem is this:
Do I assume that when I instantiate the object imsRequest thus;
IMSRequest imsRequest = new IMSRequest();
imsRequest.startIMS(response); I am no longer in a static method? That's what I thought. But the problem is that, in the class, IMSRequest I start to get compile problems saying that I can't access non-static variables from a static method, and so on and so on.
I know I can cheat by changing these to static variables, but there are some specific variables that just shouldn't be static. It seems that something has escaped me. Can anyone point out what it is?
Many thanks for your time and I will gladly post more code/explain my problem in more detail, if it helps you to explain it to me.
Damian

Can I just ask you one more question though?Okay, but I warn you: it's 1:00 a.m., I've been doing almost nothing but Java for about 18 hours, and I don't do servlets, so don't take any of this as gospel.
If, however, from another class (FrontPage for
example), I call ((new.IMSRequest().writeHTML) or
something like that, then I'm creating a new instance
of IMSRequest (right?)That's what new does, yes.
and therefore I am never going
to see the information I need from my original
IMSRequest instance. Am I right on this?I don't know. That's up to you. What do you do with the existing IMS request when you create the new FrontPage? Is there another reference to it somewhere? I don't know enough about your design or the goal of your software to really answer.
On the other hand, IMSRequest is designed to run
continuously (prehaps for hours), so I don't really
want to just print out a continuous stream of stuff to
the browser. How can I though, every so often, call
the status of this instance of this servlet?One possibility is to pass the existing IMSRequest to the FrontPage and have it use that one, rather than creating its own. Or is that not what you're asking? Again, I don't have enough details (or maybe just not enough functioning brain cells) to see how it all fits together.
One thing that puzzles me here: It seems to me that FP uses IMSReq, but IMSReq also uses FP. Is that the case? Those two way dependencies can make things ugly in a hurry, and are often a sign of bad design. It may be perfectly valid for what you're doing, but you may want to look at it closely and see if there's a better way.

When should I use static variable and when should not? Java essential

When should I use static variable and when should not? Java essential

Static => same value for all instances of the class.
Non-static => each instance can have its own value.
Which you need in which circumstances is completely up to you.

Favorite / Best Practice / Useful MTE's ??!?!

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??

Any Best Practices (i.e. DOs and Don'ts) for source to target MAPPINGs?

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What is the BEST practice - use BO or Java Object in process as webservice

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Hi Mark,
Thanks for your response. I also wanted to use java object only. When I use java object as process input argument..it is fine. But when I try to create Process web service, I am getting compilation error - "data type not supported".....
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Looking for best practices using Linux

I use Linux plataform to all the Hyperion tools, we has been problems with Analyzer V7.0.1, the server hangs up ramdomly. I'm looking for a Linux best practices using Analyzer, Essbsae, EAS, etc. I'll appreciate any good or bad comments related Hyperion on Linux OS. Thanks in advance. Mario Guerrero Mexico

Hi, did you search for patches? It can be known problem. I use all Hyperion tools on Windows without any big problem. Hope this helps, Grofaty

I need to record two camera interview shoots and turn the video around quickly. What is the best solution using a MacBook Pro and final cut pro?

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Best Practices Used in CMS

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Hi
U can try checking this document to know info about CMS
(How To Transport XI Content Using CMS)
https://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/docs/library/uuid/f85ff411-0d01-0010-0096-ba14e5db6306
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How to configuring the CMS for XI?
Business System Groups - CMS

What is the best practice to set Captivate variables from Get (less ideal) and Post (more ideal)?

We are trying to set a couple of variables in Captivate 7 by posting the information from a URL. Is there a best practice for doing this, or does it require a custom JS or other call in order to do this?
Essentially, we want to pass three variables from a URl to named variables in a Captivate 7 swf so that the information can be drawn from a database, and does not need to be entered by the user.
Suggestions, thoughts, pointers to where we may be able to find this information - all would be greatly appreciated!

Not sure how Captivate treats FlashVars internally, but the native html template includes a script to read URL parameters:
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var intTemp = strURLFull.indexOf("?");
var strURLParams = "";
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It also has a script to add variables but you'd have to parse the variables first first to use it:
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Best practice when developing APEX apps and using a SVN repository

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I wanted to get your opinion on best practice regarding how to use SVN and APEX combined.
The idea is basically how to structure and how to save APEX apps the best way in a repository.
I am currently working with a custom SVN structure, not using the default TRUNC/TAGS one : every app has a folder , under every app folder i have PAge number folders, and for each page reports, regions and global objects separated.
This helps me because its more readable then saving the whole page export, its good for small changes and i have a clear overview of every bit and piece.
What is everybody else using or is there a best practice to follow here that i dont know?
Kind regards,
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@tomaugerdotcom
Something like this might help: https://testflightapp.com/
Concevably, you could roll your own internal service if that particular one doesn't suit you. (I don't have any knowledge about how they are doing it, but it shouldn't be hard to figure out since Apple's constraining rules would only allow a few possibilities.)
USB app install and debugging isn't supported on iOS. You have to use wireless.
Another option specifically for multi-touch dev/testing, is to use an Android device.

Idoc processing best practices - use of RBDAPP01 and RBDMANI2

We are having performance problems in the processing of inbound idocs. The message type is SHPCON, and transaction volume is very high. I am a functional consultant, not an ABAP developer, but will try my best to explain our current setup.
1)     We have a number of message variants for the inbound SHPCON message, almost all of which are set to trigger immediately upon receipt under the Processing by Function Module setting.
2)      For messages that fail to process on the first try, we have a batch job running frequently using RBDMANI2.
We are having some instances of the RBDMANI2 almost every day which get stuck running for a very long period of time. We frequently have multiple SHPCON idocs coming in containing the same material number, and frequently have idocs fail because the material in the idoc has become locked. Once the stuck batch job is cancelled and the job starts running again normally, the materials unlock and the failed idocs begin processing. The variant for the RBDMANI2 batch job is currently set with a packet size of 1 and without parallel processing enabled.
I am trying to determine the best practice for processing inbound idocs such as this for maximum performance in a very high volume system. I know that RBDAPP01 processes idocs in status 64 and 66, and RBDMANI2 is used to reprocess idocs in all statuses. I have been told that setting the messages to trigger immediately in WE20 can result in poor performance. So I am wondering if the best practice is to:
1)     Set messages in WE20 to Trigger by background program
2)     Have a batch job running RBDAPP01 to process inbound idocs waiting in status 64
3)     Have a periodic batch job running RBDMANI2 to try and clean up any failed messages that can be processed
I would be grateful if somebody more knowledgeable than myself on this can confirm the best practice for this process and comment on the correct packet size in the program variant and whether or not parallel processing is desirable. Because of the material locking issue, I felt that parallel processing was not desirable and may actually increase the material locking problem. I would welcome any comments.
This appeared to be the correct area for this discussion based upon other discussions. If this is not the correct area for this discussion, then I would be grateful if the moderator could re-assign this discussion to the correct area (if possible) or let me know the best place to post it. Thank you for your help.

Hi Bob,
Not sure if there is an official best practice, but the note 1333417 - Performance problems when processing IDocs immediately does state that for the high volume the immediate processing is not a good option.
I'm hoping that for SHPCON there is no dependency in the IDoc processing (i.e. it's not important if they're processed in the same sequence or not), otherwise it'd add another complexity level.
In the past for the high volume IDoc processing we scheduled a background job with RBDAPP01 (with parallel processing) and RBDMANIN as a second step in the same job to re-process the IDocs with errors due to locking issues. RBDMANI2 has a parallel processing option, but it was not needed in our case (actually we specifically wouldn't want to parallel-process the errors to avoid running into a lock issue again). In short, your steps 1-3 are correct but 2 and 3 should rather be in the same job.
Also I believe we had a designated server for the background jobs, which helped with the resource availability.
As a side note, you might want to confirm that the performance issues are caused only by the high volume. An ABAPer or a Basis admin should be able to run a performance trace. There might be an inefficiency in the process that could be adding to the performance issue as well.
Hope this helps.

"requires unreachable" warning emitted when using static variables and the singleton pattern

I'm implementing code contracts on an existing code base and I've come across this situation in a few places. Wherever we have additional logic with code contracts where a singleton instance is instantiated, all code contracts emit a "reference use
unreached", or "requires unreachable" warning.
The code below demonstrates this.
static string instance = null;
static string InstanceGetter()
if (instance == null)
instance = "initialized";
AdditionalLogic(instance); // requires unreachable warning on this line
return instance;
static void AdditionalLogic(string str)
Contract.Requires(str != null);
Console.WriteLine(str);

Would the class get unloaded even if the Singleton object has some valid/reachable references pointing to it?
On a different note, will all the objects/instances of a class get destroyed if the class gets unloaded.That's the other way round, really: instances cannot be garbage-collected as long as they are strongly reachable (at least one reference pointing to them), and classes cannot be unloaded as long as such an instance exists.
To support tschodt's point, see the JVM specifications: http://java.sun.com/docs/books/jvms/second_edition/html/Concepts.doc.html#32202
*2.17.8 Unloading of Classes and Interfaces*
A class or interface may be unloaded if and only if its class loader is unreachable. The bootstrap class loader is always reachable; as a result, system classes may never be unloaded.
Will the same case (Custom ClassLoader getting unloaded) occur if I write the singleton using the code wherein we lazily initialize the Singleton (and actually create a Singleton instance rather than it being a Class/static variable).You should check the meaning of this vocabulary ("object", "instance", "reference"): http://download.oracle.com/javase/tutorial/java/javaOO/summaryclasses.html
The difference between the lazy vs eager initializations is the time when an instance is created. Once it is created, it will not be garbage collected as long as it is reachable.
Now I'm wondering, whether being referenced by a static attribute of a class guarantees being reachabe. I'm afraid not (see the JLS definition of reachable: http://java.sun.com/docs/books/jls/third_edition/html/execution.html#44762). That is, again, unless the class has been loaded by the system class loader.

What is the best practice to connect 2 sites and replicate ADDS between 2 different sites using windows server 2012 r2?

I found that there is new features remote access inside windows server 2012 r2 which is much more easier. Is there anybody can suggest me how to connect 2 different sites and it will be the tunnel to replicate ADDS (RW) between both sites.

See this
https://social.technet.microsoft.com/Forums/windowsserver/en-US/133e7780-6a59-4bd7-906b-70830bea48d0/sites-connections-best-practice?forum=winserverDS
Regards,
Biswajit
MCTS, MCP 2003,MCSA 2003, MCSA:M 2003, CCNA, Enterprise Admin, ITIL F 2011
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Best Practice: Using a static variables and methods vs singleton pattern

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