MVC Separation: Static POJO Methods as Controller

Hi All.
I am designing my first Java EE app. It is a web-only/no-EJB app but I still want to clearly separate view code and controller code within my web container.
I am thinking to do this by making a "ViewServlet" class and a "ControllerPOJO" class. The ViewServlet will just pass requests on to the ControllerPOJO and format the returned, processed data to send it back to the client. The ControllerPOJO will have no member data, just static methods like ControllerPOJO.processRequest( ) or something.
My questions are:
As I understand it the servlet connection/thread pool is managed by the web container, but POJO threading is not specially managed. In the design I described will the static ControllerPOJO method just execute in the thread of the ViewServlet instance that calls it, the same as if all the code was in the servlet class, or could the threading/connection throughput act differently somehow?
Is this design orthodox? Maybe what I actually want is a ControllerServlet and a ViewPOJO? Or two servlets, ControllerServlet and ViewServlet?
Thanks,
Bishop

will the static ControllerPOJO method just execute in the thread of the ViewServlet instance that calls it, the same as if all the code was in the servlet class, or could the threading/connection throughput act differently somehow?The general principles of Java Concurrency hold true for Java Servlet as well. Unless a new thread is created to execute the Callee method, both of them will execute in same thread.
Is this design orthodox? Maybe what I actually want is a ControllerServlet and a ViewPOJO? Or two servlets, ControllerServlet and ViewServlet?Use a controller Servlet for request processing and selecting views. The controller Servlet receives the requests from the client and maps them to an appropriate business model. Based on the results of the operation and state of the model, the controller then selects the next view to display. Finally, the controller generates the selected view and transmits it to the client for presentation. Please check this link for details
[http://java.sun.com/blueprints/guidelines/designing_enterprise_applications_2e/web-tier/web-tier5.html|http://java.sun.com/blueprints/guidelines/designing_enterprise_applications_2e/web-tier/web-tier5.html]

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Calling view method in controller

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Edited by: 978940 on 2012-12-27 12:32

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Right now I have just given a work around where Im triggering <b>LoadData()</b> of the <b>COmponent COntroller</b> from the <b>wdDoInit</b> of the <b>VIEW</b>.
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Calling static synchronized method in the constructor

Is it ok to do so ?
(calling a static synchronized method from the constructor of the same class)
Please advise vis-a-vis pros and cons.
regards,
s.giri

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a method should be bound to the instance (made non-static) if it operates on the instance's (non-static) variables.
you should not modify the state of the class object (the static variables) within the instance (non-static) method - rather, relegate that to the class's methods.
although it is permitted, i do not access the static methods through an instance object. i only access static methods through the class object for clarity.
and since the instance variables are not part of the class object itself, the language cannot and does not allow access to non-static variables and methods through the class object's methods.

Does not contain a static 'Main' method suitable for an entry point_

Hello
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Hi bkshn,
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https://msdn.microsoft.com/en-us/data/ee712907#codefirst
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class Program
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Console.ReadKey();
And you could start to learn the EF from the following MSDN blogs.
https://msdn.microsoft.com/en-us/data/ee712907
If you have any other concern regarding this issue, please feel free to let me know.
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Youjun Tang
We are trying to better understand customer views on social support experience, so your participation in this interview project would be greatly appreciated if you have time. Thanks for helping make community forums a great place.
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Projectname.exe' does not contain a static 'Main' method suitable for an entry point .

Hi,
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Thank You!

Go to your App.Xaml and R-Click Go to Properties
Check whether the Build Action is ApplicationDefinition
If not change it to ApplicationDefinition. Clean the code (solution ) and Deploy..
Chears....

Solution for Windows Store app "projectname.exe" does not contain a static 'Main' method suitable for an entry point . Error.

Hi,
I'm developed a blog reader for windows 8 store app. It was perfectly worked before. But suddenly it started to miss behave and I got an
error. No other errors were there other than that.
Error
Program c:\Users\.........\Desktop\Blog_Reader\Blog_Reader\obj\Release\intermediatexaml\Blog_Reader.exe' does not contain a static 'Main'
method suitable for an entry point.
C:\Users\..........\Desktop\Blog_Reader\Blog_Reader\CSC Blog_Reader
But I found the solution while I fixing it.
Solution for that is like below.
Go to your App.Xaml and Right-Click thenGo to Properties
Check whether the Build Action is
ApplicationDefinition
If not change it to ApplicationDefinition.
Clean the code (solution) and Deploy
Now the error is fiexed.

Hi Robana,
Good sharing on the Technet.
This will definitely benefit other who may encounter the same issue as yours.
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TechNet Community Support

Problem with OSB 11g - Unable to call non-static java methods

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Technical standpoint: Do you know why OSB is not able to call non-static methods?
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I have a set of classes where is class is identified with a unique ID number. So each class has a public static int getId() method. Each class also has either a constructor that takes a byte array or a static factory method that takes a byte array.
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What I was hoping to do was something like this>>>
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What about something like this?
public interface Initializable
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public class Factory
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Static synchronized methods VS non-static synchronized methods ??

what is the difference between static synchronized methods and non-static synchronized methods as far as the behavior of the threads is concerned? if a thread is in static synchronized method can another thread access simple (ie. non static) synchronized methods?

javanewbie80 wrote:
Great. Thanks. This whole explanation made a lot of sense to me.Cool, glad I was able to help!
Probably I was just trying to complicate things unnecessarily.It's a classic case of complexity inversion. It seems simpler to say something like "synchronization locks the class" or "...locks the method" than to give my explanation and then extrapolate the implications. Just like the seemingly simpler, but incorrect, "Java passes objects by reference," vs. the correct "Java passes references by value," or Java's seemingly complex I/O vs. other languages' int x = readInt(); or whatever.
In the seemingly complex case, the primitive construct is simpler, but the higher level construct requires more assembly or derivation of the primitive constructs, making that case seem more complicated.
Okay, I just re-read that, and it seems like I'm making no sense, but I'll leave it, just in case somebody can get some meaning out of it. :-)

Static factory methods, instead of constructor

Hi All,
why we use static factory methods, instead of constructor.
Apart from Singleton class , what is use of static factory methods ?
Thanks in Advance,
Rishi

One reason for using factories is that they simplify creating instances of immutable classes that might otherwise have messy constructors with lots of arguments.

Static Classes/Methods vs Objects/Instance Classes/Methods?

Hi,
I am reading "Official ABAP Programming Guidelines" book. And I saw the rule:
Rule 5.3: Do Not Use Static Classes
Preferably use objects instead of static classes. If you don't want to have a multiple instantiation, you can use singletons.
I needed to create a global class and some methods under that. And there is no any object-oriented design idea exists. Instead of creating a function group/modules, I have decided to create a global class (even is a abstract class) and some static methods.So I directly use these static methods by using zcl_class=>method().
But the rule above says "Don't use static classes/methods, always use instance methods if even there is no object-oriented design".
The book listed several reasons, one for example
1-) Static classes are implicitly loaded first time they are used, and the corresponding static constructor -of available- is executed. They remain in the memory as long as the current internal session exists. Therefore, if you use static classes, you cannot actually control the time of initialization and have no option to release the memory.
So if I use a static class/method in a subroutine, it will be loaded into memory and it will stay in the memory till I close the program.
But if I use instance class/method, I can CREATE OBJECT lo_object TYPE REF TO zcl_class then use method lo_object->method(), then I can FREE lo_object to delete from the memory. Is my understanding correct?
Any idea? What do you prefer Static Class OR Object/Instance Class?
Thanks in advance.
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@Naimesh Patel
So you recommend to use instance class/methods even though method logic is just self-executable. Right?
<h3>Example:</h3>
<h4>Instance option</h4>
CLASS zcl_class DEFINITION.
METHODS add_1 IMPORTING i_input type i EXPORTING e_output type i.
METHODS subtract_1 IMPORTING i_input type i EXPORTING e_output type i.
ENDCLASS
CLASS zcl_class IMPLEMENTATION.
METHOD add_1.
    e_output = i_input + 1.
ENDMETHOD.
METHOD subtract_1.
    e_output = i_input - 1.
ENDMETHOD.
ENDCLASS
CREATE OBJECT lo_object.
lo_object->add_1(
exporting i_input = 1
importing e_output = lv_output ).
lo_object->subtract_1(
exporting i_input = 2
importing e_output = lv_output2 ).
<h4>Static option</h4>
CLASS zcl_class DEFINITION.
CLASS-METHODS add_1 IMPORTING i_input type i EXPORTING e_output type i.
CLASS-METHODS subtract_1 IMPORTING i_input type i EXPORTING e_output type i.
ENDCLASS
CLASS zcl_class IMPLEMENTATION.
METHOD add_1.
    e_output = i_input + 1.
ENDMETHOD.
METHOD subtract_1.
    e_output = i_input - 1.
ENDMETHOD.
ENDCLASS
CREATE OBJECT lo_object.
lo_object->add_1(
zcl_class=>add_1(
exporting i_input = 1
importing e_output = lv_output ).
lo_object->subtract_1(
zcl_class=>subtract_1(
exporting i_input = 2
importing e_output = lv_output2 ).
So which option is best? Pros and Cons?

Static abstract methods - how can I avoid them?

Hi everybody,
just found out that java doesn't allow static abstract methods nor static methods in interfaces. Although I understand the reasons, I can't think of how to change my design to gain the required behavior without the need of static abstract methods.
Here's what I want to do and how my thoughts lead to static abstract methods:
ClassA provides access to native code (c-dll, using jna). The path to the dll can be set programmatically. Here's a draft of the class:
public ClassA {
   private static String path;
   public static void setRealtivePath(String path) {
      //check if path exists and is not null -> get absolute path
      setPath(path);
   public static void setPath(String absolutePath) {
      this.path = path;
//code to provide access to native lib
}There is some more classes which provide access to different dlls (therefore the code for accessing the dlls differs from ClassA). Although this works, the setRelativePath method has to be implemented in each class. I thought it would be nice to put this method into a abstract super class that looks like this:
public abstract class superClass {
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   //force inherting class to implement a static method
   public static abstract void setPath(String absolutePath);
}thus simplifying ClassA and it's look-a-likes:
public ClassA {
   private static String path;
   @Override
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//code to provide access to native lib
}Since static abstract methods (and overriding static methods) is not allowed, this doesn't work.
I hope someone can catch my idea ;). Any suggestions how to do this in a nice clean way?
Thanks in advance,
Martin
Edited by: morty2 on Jul 22, 2009 2:57 AM

First of all, thanks a lot for your answer.
YoungWinston wrote:
Actually, you can "override" static methods (in that you can write the same method for both a subclass and a superclass, providing the superclass method isn't final); it's just that it doesn't work polymorphically. The "overriding" method masks the overridden one and the determination of what gets called is entirely down to the declared type.Yes, I know that. There's one problem: Your suggestion means that I simply have to drop the abstract modifier in the super classes setPath method. However, since the super class calls the setPath method (and not the inherting classes!) it will always be the super classes' method being called.
YoungWinston wrote:
Why are you so concerned with making everything static? Seems to me that the simplest solution would be to make all the contents instance-based.I want ClassA and it's look-a-likes to be set up properly at application start up, be accessible quite anytime and easily, they don't do anything themselves except for setting the path and calling into the native library which does the math. (Compareable to how you call e.g. Math.cos()). Therefore I don't think that an instance-based solution would be a better approach.
YoungWinston wrote:
Furthermore, you could make the class immutable; which might be a good thing - I'm not sure I'd want someone being able to change the pathname after I've >set up a class like this.Thanks for that!
PS: As mentioned in my first post, I do have a working solution. However, I'm really corious about finding a nicer and cleaner way to do it!
Martin

Synchronizing methods and a static main method

I have a class with a static main method, calling 3 different jdbc updates.
I want to make sure this is thread safe when called for various clients.
It's goes:
args[0] = clientI
update 1:update field1 where clientid = client1
update 2:update field2 where clientid = client1
update 3:update field3 where clientid = client1I assume I am in jeopardy of mixing up my data?
I don't think I can synchronize a main method, nor would it do any good to synchronize the class?
Should I break the updates into methods, then synchronize them, or synchronize parts of the code?
you opinion would help greatly.

You haven't provided enough information.
Are those updates occurring sequentially? Then it's threadsafe.
Are they running in different threads? Then to make them threadsafe you'll need proper synchronization, or a database transaction.
Of course, looking at those particular updates, I don't see any reason why you'd need to worry about thread safety. They look to be independent of each other. Or perhaps you meant you need them to be atomic? That is, any query will see either the old values of all three fields, or the new values of all three fields. Nobody will be able to see the new values for fields 1 and 2, but the old value for field 3. If that's the case, then those three updates need to be in a database transaction.

Static abstract method equivalent?

From the forum thread:
http://forum.java.sun.com/thread.jspa?forumID=31&threadID=5202376
baftos wrote:
On the othe hand OP had a legitimate desire.
How can a superclass force its subclasses to
provide a certain class (as opposed to instance) behaviour?
Do other languages provide something like this?I like to have a static abstract method in a super abstract class:
public static abstract Behavior getClassMarker();And each sub concrete class should have:
public static Behavior getClassMarker(){
return new Behavior(-- parameters --);
}Could we have an equivalent that current Java allows? Or, do we see some good news on the horizon?

Normally you create an instance with the metadata for the type, which annotations let you do:package dog;
abstract class Dog {
abstract String getBark() ;
Dog () {
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DogBreed getBreed () { return getClass().getAnnotation(DogBreed.class); }
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface DogBreed {
String genericBark () ;
String name () ;
@DogBreed(name="Bulldog", genericBark="GrrrGrrrGrrr")
class Bulldog extends Dog {
String getBark() {
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@DogBreed(name="Pomeranian", genericBark="Pirrr")
class Pomeranian extends Dog {
String getBark() {
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public class DogAnnotationTest {
public static void main (String...args) {
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    System.out.println("The generic bark of the " + pomme.getBreed().name() + " breed is "
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}The limitation is that you can only annotate with simple types, so you're stuck with the abstract factory pattern if you want the creation. Not that that's a bad thing, as it lets you create instances of classes which haven't been loaded yet.

[svn:osmf:] 10996: Changing MediaElementLayoutTarget to be constructed via a static ' getInstance' method, instead of by its constructor.

Revision: 10996
Author:   [email protected]
Date:     2009-10-19 07:45:26 -0700 (Mon, 19 Oct 2009)
Log Message:
Changing MediaElementLayoutTarget to be constructed via a static 'getInstance' method, instead of by its constructor. This prevents the construction of multiple instances that reference one single media-element. Updating client code accordingly.
Extending layout unit tests. Adding a custom renderer, checking calculation and layout passes invokation counts.
Modified Paths:
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    osmf/trunk/framework/MediaFramework/org/osmf/composition/ParallelViewableTrait.as
    osmf/trunk/framework/MediaFramework/org/osmf/composition/SerialViewableTrait.as
    osmf/trunk/framework/MediaFramework/org/osmf/gateways/RegionSprite.as
    osmf/trunk/framework/MediaFramework/org/osmf/layout/DefaultLayoutRenderer.as
    osmf/trunk/framework/MediaFramework/org/osmf/layout/LayoutContextSprite.as
    osmf/trunk/framework/MediaFramework/org/osmf/layout/LayoutRendererBase.as
    osmf/trunk/framework/MediaFramework/org/osmf/layout/MediaElementLayoutTarget.as
    osmf/trunk/framework/MediaFramework/org/osmf/utils/MediaFrameworkStrings.as
    osmf/trunk/framework/MediaFrameworkFlexTest/org/osmf/composition/TestParallelViewableTrai t.as
    osmf/trunk/framework/MediaFrameworkFlexTest/org/osmf/gateways/TestRegionSprite.as
    osmf/trunk/framework/MediaFrameworkFlexTest/org/osmf/layout/TestDefaultLayoutRenderer.as
    osmf/trunk/framework/MediaFrameworkFlexTest/org/osmf/layout/TestLayoutUtils.as
    osmf/trunk/framework/MediaFrameworkFlexTest/org/osmf/layout/TestMediaElementLayoutTarget. as
Added Paths:
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AlexCox, can you clarify that once you get the default model out and save it in the temp var, that your ONLY access to the data is then through temp and never through the JList methods?
Quick question for everyone: Are any of you using JList.setListData to set you initial dataset? I think that is where the bug lies. When I do not use it and start with an empty list, I am able to add to that list, and then remove from that list using the following line:
((DefaultListModel)myList.getModel).remove(###);
And this cast works everytime.
But when I start that list out with some data such as:
myList.setListData(myStringArray);
and then try to execute the above line, boom! I get the ClassCast exception.
I think setListData creates a whole new model which is an inner class to JList (which seems stupid when DefaultListModel seems made for this).
Just my thoughts on where the problem lies. I'll add my data directly to the list and see if that works better.
PK

MVC Separation: Static POJO Methods as Controller

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