class-design

What is the best way to share data between separate classes in Java? I have a bunch of variables that are used by different classes in separate files in different ways. Let me try to illustrate a simplified version of my problem: This was my code before: public class Top_Level_Class(){ int x, y; // gets user input which changes x, y; public void main(){ int p, q, r, s; // compute p, q, r, s doA(p,q,r); doB(q,r,s); } public void doA(int p, int q, int r){ // do something that requires x,y and p, q, r } public void doB(int q, int r, int s){ // does something else that requires x, y and q, r, s }

I'm interested in hearing some discussion about class attributes in Python. For example, what is a good use case for class attributes? For the most part, I can not come up with a case where a class attribute is preferable to using a module level attribute. If this is true, then why have them around? The problem I have with them, is that it is almost too easy to clobber a class attribute value by mistake, and then your "global" value has turned into a local instance attribute. Feel free to comment on how you would handle the following situations: Constant values used by a class and/or sub

Suppose I have a class 'Application'. In order to be initialised it takes certain settings in the constructor. Let's also assume that the number of settings is so many that it's compelling to place them in a class of their own. Compare the following two implementations of this scenario. Implementation 1: class Application { Application(ApplicationSettings settings) { //Do initialisation here } } class ApplicationSettings { //Settings related methods and properties here } Implementation 2: class Application { Application(Application.Settings settings) { //Do initialisation here } class Settings

My app uses two databases (separate files). To handle these databases I have created two Helper classes which extend SQLiteOpenHelper, one for each database. I am now going to add a third database and wonder whether I need to create yet another Helper class (and if I used a 4th and a 5th database would I need even more Helper classes), or can I use the same Helper class for multiple databases? The problem that I see with trying to use just one Helper class is that I can't see how to pass the name of the individual database files to the Helper. At present the name of the database is hard-coded

The diagram below is my very first attempt at creating a UML class diagram describing a user login into a website. I'm sure its a poor design and full of flaws, but I'm hoping to learn from you guys how you would design a simple login like this. I'm particularly interested in your use of design patterns and which patterns you would use, how you would implement it in the design, and why. Any advise, criticisms, comments and suggestions will be really appreciated. Thanks in advance. Arthur Ronald Here is how we implement this funcionallity As you can see, we have many Application (Here, it

In the (otherwise) excellent book C++ Coding Standards , Item 44, titled "Prefer writing nonmember nonfriend functions" , Sutter and Alexandrescu recommend that only functions that really need access to the members of a class be themselves members of that class. All other operations which can be written by using only member functions should not be part of the class. They should be nonmembers and nonfriends. The arguments are that: It promotes encapsulation, because there is less code that needs access to the internals of a class. It makes writing function templates easier, because you don't