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  • More swing design & actions

    - by takoi
    Im pretty new to gui programming so i've been reading through every post on this site about swing and design. Whats been answered over and over again is that one should have a class which handles all the action. Like this: (GUI being some JFrame) Now, this works great for one-way actions, like OpenDialog. But the actions for buttons in DialogA and B will have to have access to all the components (there will be many) in its dialog, and the controller. This is where im stuck. The only sane way i can see is to put it in DialogA/B but i would then need to pass the controller all the way down, through classes that dont even need it, and it'll get all spaghetti. Really dont want that. Someone must have encountered this problem before. So where should i put this Action? Or should i just drop the whole design?

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  • new Integer vs valueOf

    - by LB
    Hi, I was using Sonar to make my code cleaner, and it pointed that I'm using new Integer(1) instead of Integer.valueOf(1). Because it seems that valueOf does not instantiate a new object so is more memory-friendly. How can valueOf not instantiate a new object ? How does it work ? Is this true for all integers ? thanks.

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  • Many-to-many relationship in oop

    - by Manu
    what is best way to model many-to-many relationship? lets say we have a two classes , Team and Player any given Player can be in multiple Team s any Team can have as many Player s as they like I like to call methods like playerX.getTeamList() to get the list of all the Team s he/she is in teamY.getPlayerList() to get the list of all the Player s in the team (or have some other way to do this effectively) I can think of two ways of doing this , but they just don't feels like good oop pattens. can you think of any good ways , perhaps a design patten ?

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  • Efficiently store last X items in an MySQL Database

    - by Saif Bechan
    I want to store the last 3 items in an MySQL database in an efficient way. So when the 4th item is stored the first should be deleted. The way I do this not is first run a query getting the items. Than check what I should do then insert/delete. There has to be a better way to do this. Any suggestions?

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  • How can I achieve this kind of relationship (inheritance, composition, something else)?

    - by Tim
    I would like to set up a foundation of classes for an application, two of which are person and student. A person may or may not be a student and a student is always a person. The fact that a student “is a” person led me to try inheritance, but I can't see how to make it work in the case where I have a DAO that returns an instance of person and I then want to determine if that person is a student and call student related methods for it. class Person { private $_firstName; public function isStudent() { // figure out if this person is a student return true; // (or false) } } class Student extends Person { private $_gpa; public function getGpa() { // do something to retrieve this student's gpa return 4.0; // (or whatever it is) } } class SomeDaoThatReturnsPersonInstances { public function find() { return new Person(); } } $myPerson = SomeDaoThatReturnsPersonInstances::find(); if($myPerson->isStudent()) { echo 'My person\'s GPA is: ', $myPerson->getGpa(); } This obviously doesn't work, but what is the best way to achieve this effect? Composition doesn't sond right in my mind because a person does not “have a” student. I'm not looking for a solution necessarily but maybe just a term or phrase to search for. Since I'm not really sure what to call what I'm trying to do, I haven't had much luck. Thank you!

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  • Should the program logic reside inside the gui object class or be external to the class?

    - by hd112
    I have a question about how to structure code in relation to GUI objects. Suppose I have a dialog that has a list control that has a bunch of names obtained from a database. The user can edit the names. Does the logic reside inside that dialog class or should it be from the outside. To illustrate what I mean, here’s some pseudo code showing the structure of the code when the logic is handled outside the dialog class: NamesDialog : wxDialog { Private: ..stuff.. Public: ... SetNames(wxStringArray names); wxStringArray GetNames(); ..stuff.. } So the user of the class would do something like: wxStringArray names = DatabaseManager::Get()->GetNames(); names.Sort(); NamesDialogObject.SetNames(names); NamesDialogObject.ShowModal(); wxStringArray modified_names = NamesDialogObject.GetNames(); AddToDatabase(modified_names); //or something like this. On the other hand, the database logic can reside inside the NamesDialog class itself. In the show method I can query the database for the names and as the user interacts with the controls (list control in this case), the database can be updated from the event handlers. As a result the NamesDialog class only has the Show() method as there is no need to use SetNames or GetNames() etc. Which method is generally preferred? I don’t have much work experience so I’m not sure which is the proper way to handle it. Sometimes it's easier to handle everything in the class but getting access to objects it interacts with can be challenging. Generally can do it by having the relevant objects be singletons like the database manager in the above example.

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  • group by country with ActiveRecords in Rails

    - by Adnan
    Hello, I have a table with users: name | country | .. | UK | .. | US | .. | US | .. | UK | .. | FR | .. | FR | .. | UK | .. | UK | .. | DE | .. | DE | .. | UK | .. | CA | . . What is the most efficient way with ActiveRecords to get the list of countries in my view and for each country how many users are from, so: US 123 UK 54 DE 33 . . .

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  • Decorator Design Pattern Use With Service Objects (wSingleton)

    - by Dustin
    I'm working on a project where I need to add some functionality to a service object and using a decorator to add it in seems like a good fit. However, I've only ever used decorators with simple beans, never on a singleton like a service object. Has anyone ever done this before and what are the pros and cons? In this case I don't think creating a subclass will work so a decorator seems to be a good fit. What are your thoughts on doing this?

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  • Boost shared_ptr use_count function

    - by photo_tom
    My application problem is the following - I have a large structure foo. Because these are large and for memory management reasons, we do not wish to delete them when processing on the data is complete. We are storing them in std::vector<boost::shared_ptr<foo>>. My question is related to knowing when all processing is complete. First decision is that we do not want any of the other application code to mark a complete flag in the structure because there are multiple execution paths in the program and we cannot predict which one is the last. So in our implementation, once processing is complete, we delete all copies of boost::shared_ptr<foo>> except for the one in the vector. This will drop the reference counter in the shared_ptr to 1. Is it practical to use shared_ptr.use_count() to see if it is equal to 1 to know when all other parts of my app are done with the data. One additional reason I'm asking the question is that the boost documentation on the shared pointer shared_ptr recommends not using "use_count" for production code.

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  • does anyone see any issues with this thread pattern?

    - by prmatta
    Here is a simple thread pattern that I use when writing a class that needs just one thread, and needs to a specific task. The usual requirements for such a class are that it should be startable, stopable and restartable. Does anyone see any issues with this pattern that I use? public class MyThread implements Runnable { private boolean _exit = false; private Thread _thread = null; public void start () { if (_thread == null) { _thread = new Thread(this, "MyThread"); _thread.start(); } } public void run () { while (_exit) { //do something } } public void stop () { _exit = true; if (_thread != null) { _thread.interrupt(); _thread = null; } } } I am looking for comments around if I am missing something, or if there is a better way to write this.

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  • How to implement the disposable pattern in a class that inherits from another disposable class?

    - by TheRHCP
    Hi, I often used the disposable pattern in simple classes that referenced small amount of resources, but I never had to implement this pattern on a class that inherits from another disposable class and I am starting to be a bit confused in how to free the whole resources. I start with a little sample code: public class Tracer : IDisposable { bool disposed; FileStream fileStream; public Tracer() { //Some fileStream initialization } public void Dispose() { this.Dispose(true); GC.SuppressFinalize(this); } protected virtual void Dispose(bool disposing) { if (!disposed) { if (disposing) { if (fileStream != null) { fileStream.Dispose(); } } disposed = true; } } } public class ServiceWrapper : Tracer { bool disposed; ServiceHost serviceHost; //Some properties public ServiceWrapper () { //Some serviceHost initialization } //protected override void Dispose(bool disposing) //{ // if (!disposed) // { // if (disposing) // { // if (serviceHost != null) // { // serviceHost.Close(); // } // } // disposed = true; // } //} } My real question is: how to implement the disposable pattern inside my ServiceWrapper class to be sure that when I will dispose an instance of it, it will dispose resources in both inherited and base class? Thanks.

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  • What is the sense of "Feature Oriented Programming" (FOP) in C++, and would it make sense in Java an

    - by ivan_ivanovich_ivanoff
    Hello! Sadly, I can't remember where I read it, but... ...in C++ you can derive a class from a template parameter. Im pretty sure it was called Feature Oriented Programming (FOP) and meant to be somehow useful. It was something like: template <class T> class my_class : T { // some very useful stuff goes here ;) } My questions about this: What is the sense of such pattern? Since this it not possible in Java / C#, how this pattern is achieved in these languages? Can it be expected to be implemented in Java / C# one day? (Well, first Java would need to get rid of type erasure) EDIT: I'm really not talking about generics in Java / C# (where you can't derive a class from a generic type parameter)

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  • Sequential coupling in code

    - by dotnetdev
    Hi, Is sequential coupling (http://en.wikipedia.org/wiki/Sequential_coupling) really a bad thing in code? Although it's an anti-pattern, the only risk I see is calling methods in the wrong order but documentation of an API/class library with this anti-pattern should take care of that. What other problems are there from code which is sequential? Also, this pattern could easily be fixed by using a facade it seems. Thanks

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  • Will this be garbage collected in JVM?

    - by stjowa
    I am running the following code every two minutes via a Timer: object = new Object(this); Potentially, this is a lot of objects being created and a lot of objects being overwritten. Do the overwritten objects get garbage collected, even with a reference to itself being used in the newly created object? I am using JDK 1.6.0_13. Thanks for the help.

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  • Why is 'using namespace std;' considered a bad practice in C++?

    - by Mana
    Okay, sorry for the simplistic question, but this has been bugging me ever since I finished high school C++ last year. I've been told by others on numerous occasions that my teacher was wrong in saying that we should have "using namespace std;" in our programs, and that std::cout and std::cin are more proper. However, they would always be vague as to why this is a bad practice. So, I'm asking now: Why is "using namespace std;" considered bad? Is it really that inefficient, or risk declaring ambiguous vars(variables that share the same name as a function in std namespace) that much? Or does this impact program performance noticeably as you get into writing larger applications? I'm sorry if this is something I should have googled to solve; I figured it would be nice to have this question on here regardless in case anyone else was wondering.

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  • list all files from directories and subdirectories in Java

    - by Adnan
    What would be the fastest way to list the names of files from 1000+ directories and sub-directories? EDIT; The current code I use is: import java.io.File; public class DirectoryReader { static int spc_count=-1; static void Process(File aFile) { spc_count++; String spcs = ""; for (int i = 0; i < spc_count; i++) spcs += " "; if(aFile.isFile()) System.out.println(spcs + "[FILE] " + aFile.getName()); else if (aFile.isDirectory()) { System.out.println(spcs + "[DIR] " + aFile.getName()); File[] listOfFiles = aFile.listFiles(); if(listOfFiles!=null) { for (int i = 0; i < listOfFiles.length; i++) Process(listOfFiles[i]); } else { System.out.println(spcs + " [ACCESS DENIED]"); } } spc_count--; } public static void main(String[] args) { String nam = "D:/"; File aFile = new File(nam); Process(aFile); } }

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  • Best practice for avoiding locks on a heavily read table?

    - by Luiggi
    Hi, I have a big database (~4GB), with 2 large tables (~3M records) having ~180K SELECTs/hour, ~2k UPDATEs/hour and ~1k INSERTs+DELETEs/hour. What would be the best practice to guarantee no locks for the reading tasks while inserting/updating/deleting? I was thinking about using a NOLOCK hint, but there is so much discussed about this (is good, is bad, it depends) that I'm a bit lost. I must say I've tried this in a dev environment and I didn't find any problems, but I don't want to put it on production until I get some feedback... Thank you! Luiggi

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  • Fastest way to check for value existance.

    - by Itay Moav
    I have a list of values I have to check my input against it for existence. What is the faster way? This is really out of curiosity on how the internals work, not any stuff about premature optimization etc... 1. $x=array('v'=>'','c'=>'','w'=>); .. .. array_key_exists($input,$x); 2. $x=array('v','c','w'); .. .. in_array($input,$x);

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