We Keep Coding

What design pattern is good for applying attributes to a class that changes its behavior?

I am trying to find the best way to structure my project. What I would like to do is have a "Structure", which is made of multiple "part". These parts also will have separate attributes, for example it could be spinning, hovering, vibrating, jumping, shaking, growing, accelerating.
So for example, I might have a "structure" called human that is made of 6 "parts". I am going to set each part to one of the available options, so in this case, 2 parts are going to be arms, 2 parts are going to be legs, one part is a torso, and one part is a head. Now, I want to be able to apply the attribute spinning to one of the parts, the arm. So now I should have a human with a spinning arm.
Additionally, I would like other people to be able to create their own cusom attributes, structures, and parts.
I would like to get an idea on how I should structure my code, and apply an attribute to a part. Additionally, what design pattern would be good for this?

The requirement is to have a single interface for a composition of various objects / components.
There are 2 suitable design patterns for this requirement.
Facade (https://dzone.com/refcardz/design-patterns?chapter=17)
Composite Object (https://dzone.com/refcardz/design-patterns?chapter=15)
Facade pattern can be used when the way in which the internal components are assembled must be abstracted.
Composite object pattern can be used when the assembly of the components must be advertised.

One Listener instace for all components or an instance for each component

Short Question
I want to know if there is any good practice recommendation about write one listener instace for all components or an instance for each component.
Extended Question
I'm developing a java swing application.
In the same form i can have a dozen of components (with no relation between them) that use the same listener class. I write each of my listeners in their own class.
The listeners are used to make some validations over the data introduced on the component.
Should i create an instance of the listener class for each component, or should i use the same instance of the listener for all the components.
I can't find any good practice suggestion about this, except this comment, that does not point to any reference.

For the particular case of ActionListener, encapsulate the desired functionality using Action. The wide use of this class throughout Swing suggest its value. This simple example illustrates a few built-in text component actions; this more elaborate example shows how actions can be shared among menus and toolbars.
The alternative is an ever-growing and hard-to-maintain if-then-else ladder based on the event source.
Addendum: Ah, I misread your question. #Andrew's comment is about classes; your question asks about instances. For the former, a single listener tends to evolve toward a a known anti-pattern; earlier versions of the example cited illustrate the problem. For the latter, use only as many instances as required; I usually catch the most egregious violations in a trip through the profiler.

I think the best solution is the one that makes your code the cleanest possible.
Basically, if having one single instance doesn't complicate the code too much then you could create just one instance and share it across the components. Otherwise, you can have multiple instances.

You should choose one which keeps your code readable and maintainable.
If creating instances makes it simpler go ahead and do it but since the behavior remains the same; I believe single instance should work.

Your idea is really interesting........
Moveover if its Swing....then its already based on MVC architecture......
Model - Business Logic and Data
View - Representation of Output
Controller - On which the action is done.
Now i think its also better to have the Business Logic with its data together, so we can easily associate the logic and its corresponding data.
You can always have an a common listener for common EventSource, like JButton...
You can have 4 JButton, which do different works, now you can have a single ActionListener with switch statements..... quite easy to handle......

How can I avoid passing around a single instance of a top level component to all my subclasses

So I've been trying to see how I could best structure my code, because I have an intuitive feel that there must be a better way to achieve what I want without passing around a single object to nearly every UI class in the project.
The project I'm working on has a class RhythmWheel that extends JRootPane. The constructor then goes on to create all the components that form a RhythmWheel. For example it creates an instance of ControlPanel (which extends JPanel) and adds it to itself.
However ControlsPanel needs to have a lot of knowelgde of things that are defined in RhythmWheels like the number of wheels that are currently selected. Currently the constructor for ControlsPanel takes a RhythmWheel as an argument, and then keeps a reference to it. It uses this for things ranging for component a JFileChooser should be parented to to, and as an argument to a function that writes the revelant state of the application to an XML file.
It seems wrong to me that I'm passing around a main component across so many classes. I thought about design patterns, and figured that a singleton might be a solution to this. However I have read numerous times that singletons are evil and are an anti-pattern. I guess the MVC pattern might help, but I'm not sure how I'd implement that in Swing. And most recently I came across Dependency Injection as a possible solution.
I'm a little lost as to what I should be doing, or if I should be doing aything at all. If you'd like to glance at the code I'm working on, you can see it at https://github.com/vamega/RhythmWheels so any advice on how to proceed would be great.

if everything needs a reference to RhythmWheel then it sounds like RhythmWheel is awfully complex. maybe you can break RhythmWheel into a collection of components that (hopefully, and likely, since GUI should reflect logical structure) correspond to particular parts of the GUI?
also, why do all the GUI components keep references to the RhythmWheel (or the appropriate sub-component, if you refactor as described above)? i haven't done much spring programming, but i thought the idea was to structure things round an observer pattern. in that case, the gui components should be registering themselves as observers on the wheel components, so that they can update when the wheel changes.
and yes, this is mvc. the wheel components form your model; the gui is your view. what is less clear is what the controller is. i suspect that it is the high-level wheel.
so, in summary:
the wheel is composed of sub-components
the wheel has high-level methods that reflect what you can "do" to it
the wheel's high-level methods are what are called by actions in the view
the wheel's high-level methods make changes to the wheel's sub-components
the wheel's sub-components, when they change, inform the model, which updates
only the input parts of the view need references to the wheel; the display parts are triggered via callbacks registered with the wheel sub-components.
(to answer the original question directly, i don't see anything so bad in passing around a wheel instance, but as i suggest above, it might be better for it to "fragment" into different components as it gets "lower" into the GUI).

I don't see what's wrong with using singletons. A control panel sounds like a prime candidate for a singleton. Why would have you more than one? Same goes for the others. Anything your currently accessing in ControlPanel from RhythmWheel can be exposed through getters and setters.
Unless there's a model/view separation that you would like to decouple or a view that needs to observe model updates, I wouldn't use MVC.

OO vs Simplicity when it comes to user interaction

As a project over summer while I have some downtime from Uni I am going to build a monopoly game. This question is more about the general idea of the problem however, rather than the specific task I'm trying to carry out.
I decided to build this with a bottom up approach, creating just movement around a forty space board and then moving on to interaction with spaces. I realised that I was quite unsure of the best way of proceeding with this and I am torn between two design ideas:
Giving every space its own object, all sub-classes of a Space object so the interaction can be defined by the space object itself. I could do this by implementing different land() methods for each type of space.
Only giving the Properties and Utilities (as each property has unique features) objects and creating methods for dealing with the buying/renting etc in the main class of the program (or Board as I'm calling it). Spaces like go and super tax could be implemented by a small set of conditionals checking to see if player is on a special space.
Option 1 is obviously the OO (and I feel the correct) way of doing things but I'd like to only have to handle user interaction from the programs main class. In other words, I don't want the space objects to be interacting with the player.
Why? Errr. A lot of the coding I've done thus far has had this simplicity but I'm not sure if this is a pipe dream or not for larger projects. Should I really be handling user interaction in an entirely separate class?
As you can see I am quite confused about this situation. Is there some way round this? And, does anyone have any advice on practical OO design that could help in general?
EDIT: Just like to note that I feel I lost a little focus on this question. I am interested in the general methodology of combining OO and any external action(command line, networking, GUI, file management etc) really.

In the end, it is up to you. That is the beauty of OO, in that it is subject to interpretation. There are some patterns that should usually be adhered to, but in general it is your decision how to approach it.
However, you should carefully consider what each actor in the system should know about the rest of it. Should a property really know about the player, his account balance, and the other players? Probably not. A property should know what it costs, how much its rent is, etc.
On the other hand, should the main playing thread be concerned about trivial matters such as paying rent? Probably not. Its main concern should be the state of the game itself, such as dice rolling, whether each player wants to trade or buy or unmortgage/mortgage, things like that.
Think for a moment about the action of landing on a square. Once landed, the player has 3 options:
Buy the property
Ignore the property
Pay rent
Now, which actor in the system knows all the information required to complete that. We have the Game class, which isn't concerned with such tedium. We have the Property, which doesn't really care about the players. But the Player object knows all this information. It keeps a record of what each player owns, and can easily access the proper data.
So, if it were me, I would make a Player.performMove(Die d) method. It has easy access to the accounts. This also allows for the least coupling among classes.
But in the end, it's up to you. I'm sure people have created Monopoly clones in perfect OO, as well as Functional or Procedural languages too. In the end, use what you know and keep refactoring until you're happy with the end design.

I agree option #1 seems better.
As for "user interaction" - it all depends. You could leave some of your code in another class. For example,
// in main class
user.landOn(space);
if (space.containsProperties()) doSomething(); // Option #1 for some user-interaction code
// in User.java
public void landOn(Space s) {
// do some checks
s.land(this);
if (s.containsProperties()) {...} // Option #2
// something else?
}
// in GetMoneySpace.java
#Override
public void land(User u) {
u.awardCash(200);
// Option #3 - no properties so nothing here
}
This is far more OOP-y (and better, in my opinion) than something like
if (space.isCashAwardSpace()) {
user.awardCash(space.getAward());
}
if (user.something()) doSomething(); // Some user-interaction code

I am not entirely sure if I understand it correctly. You have always such choice when designing software. I would personally go for the first choice. One argument is personal experience with small games (Scrabble), which prooved to me that good design matters for smaller projects as well. The point of OOP is that you can think differently about your design and you get some design benefits. For example imagine how hard it will be to add new field, change existing one, reuse behaviour of one field in multiple fields.

Your first approach is the one I'd go for. It encapsulates the behaviour where it's needed. So, you'd have Space subclasses for Utilities, Properties, GotoJail, FreeParking - basically all the different cateogires of spaces. What groups a category is it's common behaviour.
Your properties spaces may themselves have a group object as a member, e.g. to group all the dark blue properties together.
As to interaction with the user, you pass a Board (or better a GameController) instance to each space, so it knows which Game it is part of and can influence the game. The Space can then invoke specific actions on the board, such as, moving a piece, asking the user a question etc. The main point is that there is separation - the user interaction is not happening inside each Space - but the space is allowed to request that some interaction happens, or that a piece is moved. It's up to your GameController to actually do the interaction or move pieces etc. This separation makes it easy to test, and also provide alternative implementations as the need may arise (E.g. different game rules in different editions/countries?)

Go with the first design. You'd have a Property class, and subclass the special properties, overriding the default behavior.
As far as interaction, you could have a Token class, and move an instance of that around the board. You have to give the user some options, but yes, from the responses, you should be calling methods on objects, not putting complex logic in the user events.
Sample classes:
Property
name
price
baseRent
houseCount
hotelCount
mortgaged
getCurrentRent()
RailRoad extends Property
Utility extends Property
Board
properties
User
token
playerName
currentProperty
ownedProperties
buyProperty()
payRentOnProperty()
mortgageProperty()
move()

Option 2 doesn't make much sense, or at least it's not as clear to me as option 1. With option 1 you don't need to handle user interaction inside your space object. You could have in your main class or a separate class dedicated to handle user interaction:
public void move(Player p, int spaces){
Space landingSpace = board.getLandingSpace(p,spaces);
landingSpace.land(p); //apply your logic here
}
As you can see, the Space class is responsible for checking the Player p that intends to land on that space. It applies any custom logic, checks if it has enough money, if it's something that the player owns, etc. Each subclass of Space will have its own set of rules, as you described in option 1.

Part of the point of object-oriented design is to simplify the representation of the problem within the solution space (i.e., modeling the system in the computer). In this case, consider the relationships between objects. Is there enough functionality in a Space to warrant abstracting that into a class, or does it make more sense for there to be discrete Property and Utility classes unrelated to Space because of the unique features of both? Is a Property a special kind of Space, or merely a field within Space? These are the kinds of problems you probably will need to grapple with in designing the game.
As far as interaction, it's generally bad news for a design when you have a 'god class' that does all the work and merely asks the other classes for information. There are plenty of ways to fall into this trap; one way to determine whether you are dealing with a god class is to look for a class name including Manager or System. Thus, it's probably not the best idea to have some sort of "game manager" that asks all the other objects for data, makes all the changes, and keeps track of everything. Eliminate these as much as possible.
God classes violate the concept of encapsulation, which involves more than data hiding (though that's certainly a big part of it). Good encapsulation means that related methods and data are part of a single object. For example, a Property doesn't need to make requests of its owner, so a field containing a reference to the Player could violate encapsulation. Some of these encapsulation violations aren't obvious at all, and can be hard to spot. When designing the object, try to determine the smallest amount of information about the object that needs to be shared with external objects. Trim out anything unnecessary.
You can obviously go about this in a lot of ways, but my design would be something like this (iteration could certainly prove it wrong):
Space class that contains basic data and methods that are common to all spaces (such as their position on the board, occupied or not, etc.).
Subclasses moving from most common (Property and Utility) to most unique (Go, Jail, FreeParking, and so on; probably singletons) with fields and methods related to each.
Player class to contain player information.
GameState class that is concerned with game state; whose turn it is, how many houses are left in the bank, and so on.
Good luck with the game and your continued studies.
Naturally, Google is your friend, but here's a sampling of things I would recommend reading:
ATM simulation (this idea is
also discussed in Rebecca
Wirfs-Brock's book below)
Object-Oriented Design Heuristics - Arthur Riel
How Designs Differ (PDF), Designing Object-Oriented Software - Rebecca Wirfs-Brock

How can I best apply OOP principles to games and other input-driven GUI apps?

Whenever I try to write graphical programs (whether a game or really any GUI app) I always wind up with one or two god classes with way too many methods (and long methods, too), and each class having far too many responsibilities. I have graphics being done at the same time as calculations and logic, and I feel like this is a really bad way to go about organizing my code. I want to get better at organizing my code and abstracting out responsibilities to different classes. Here's an example of where I'd like to start - I want to write a Minesweeper clone, just sort of as practice and to try to improve my software engineering skills. How would I go about making this nice and object-oriented? For the sake of discussion, let's just say I'm using Java (because I probably will, either that or C#). Here's some things I would think about:
should each tile inherit from JButton or JComponent and handle drawing itself?
or should the tiles just be stored as some non-graphical MinesweeperTile object and some other class handles drawing them?
is the 8-segment display countdown timer (pre-Vista, at least) a separate class that handles drawing itself?
when the user clicks, do the tiles have mouse event listeners or does some other collision detection method loop through the tiles and check each one to see if it's been hit?
I realize that there's not just one way to write a GUI application, but what are some pretty basic things I can start doing to make my code more organized, manageable, object-oriented, and just over all write better programs?
edit: I guess I should add that I'm familiar with MVC, and I was originally going to incorporate that into my question, but I guess I didn't want to shoehorn myself into MVC if that's not necessarily what I need. I did searched for topics on MVC with GUI apps but didn't really find anything that answers my specific question.
edit2: Thanks to everyone who answered. I wish I could accept more than one answer..

Here is a simple (but effective) OO design to get you started:
First create a Game object that is pure Java/C# code. With no UI or anything else platform specific. The Game object handles a Board object and a Player object. The Board object manages a number of Tile objects (where the mines are). The Player object keeps track of "Number of turns", "Score" etc. You will also need a Timer object to keep track of the game time.
Then create a separate UI object that doesn't know anything about the Game object. It is completely stand alone and completely platform dependent. It has its own UIBoard, UITile, UITimer etc. and can be told how to change its states. The UI object is responsible for the User Interface (output to the screen/sound and input from the user).
And finally, add the top level Application object that reads input from the UI object, tells the Game what to do based on the input, is notified by the Game about state changes and then turns around and tells the UI how to update itself.
This is (by the way) an adaption of the MVP (Model, View, Presenter) pattern. And (oh by the way) the MVP pattern is really just a specialization of the Mediator pattern. And (another oh by the way) the MVP pattern is basically the MVC (Model, View, Control) pattern where the View does NOT have access to the model. Which is a big improvement IMHO.
Have fun!

use a MVC framework that handles all the hard organization work for you. there's a ton of MVC framework topics on SO.
using high quality stuff written by others will probably teach you faster - you will get further and see more patterns with less headache.

I'm not suggesting this is the only way to do it, but what I would suggest is something like the following. Other people, please feel free to comment on this and make corrections.
Each tile should inherit from something and handle drawing itself. A button seems like the best solution because it already has the button drawing functionality (pressed, unpressed, etc) built in.
Each tile should also be aware of its neighbors. You would have eight pointers to each of its eight neighbors, setting them to null of course if there is no neighbor. When it goes to draw, it would query each neighbor's IsMine() function and display the count.
If none of its neighbors are a mine, it would then recurse into each neighbor's Reveal() method.
For the 7-segment display, each digit is its own class that handles drawing. Then I would make a CountdownSegmentDigit class that inherits from this class, but has additional functionality, namely CountDown(), Set(), and Reset() methods, as well as a HitZero event. Then the display timer itself is a collection of these digits, wired up to propagate zeroes left. Then have a Timer within the timer class which ticks every second and counts down the rightmost digit.
When the user clicks, see above. The tile itself will handle the mouse click (it is a button after all) and call its Reveal() method. If it is a mine, it will fire the MineExploded event, which your main form will be listening to.
For me, when I think of how to encapsulate objects, it helps to imagine it as a manufacturing process for physical parts. Ask yourself, "How can I design this system so it can be most efficiently built and reused?" Think about future reuse possibilities too. Remember the assembly process takes small pieces and builds them up into larger and larger pieces until the entire object is built. Each bit should be as independent as possible and handle its own logic, but be able to talk to the outside world when necessary.
Take the 7-segment display bit, you could have another use for it later that does not count down. Say you want a speedometer in a car or something. You will already have the digits that you can wire up together. (Think hardware: stock 7-segment displays that do nothing but light up. Then you attach a controller to them and they get functionality.)
In fact if you think hard enough, you might find you want CountUp() functionality too. And an event argument in HitZero to tell whether it was by counting up or down. But you can wait until later to add this functionality when you need it. This is where inheritance shines: inherit for your CountDownDigit and make a CountUpOrDownDigit.
Thinking about how I might design it in hardware, you might want to design each digit so it knows about its neighbors and count them up or down when appropriate. Have them remember a max value (remember, 60 seconds to a minute, not 100) so when they roll over 0, they reset appropriately. There's a world of possibilites.

The central concern of a Graphic User Interface is handling events. The user does X and you need to response or not respond to it. The games have the added complexity in that it needs to change state in real time. In a lot of cases it does this by transforming the current state into a new state and telling the UI to display the results. It does this in a very short amount of time.
You start off with a model. A collection of classes that represents the data the user wants to manipulate. This could represent the accounts of a business or vast frontiers of an unknown world.
The UI starts with defining a series of forms or screens. The idea is that is for each form or screen you create a interface that defines how the UI Controller will interact with it. In general there is one UI Controller classes for each form or screen.
The form passes the event to the UI Controller. The UI Controller then decides which command to execute. This is best done through the Command design pattern where each command is it own class.
The Command then is executed and manipulate the model. The Command then tells the UI Controller that a screen or a portion of a screen needs to be redraw. The UI Control then looks at the data in the model and uses the Screen Interface to redraw the screen.
By putting all the forms and screen behind a interface you can rip out what you have and put something different in. This includes even not having any forms at all but rather mock objects. This is good for automated testing. As long as something implements the Screen Interface properly the rest of the software will be happy.
Finally a game that has to operate in real time will have a loop (or loops) running that will be continually transforming the state of the game. It will use the UI Controller to redraw what it updated. Commands will insert or change information in the model. The next time the loop comes around the new information will be used. For example altering a vector of a object traveling through the air.
I don't like the MVC architecture as I feel it doesn't handle the issues of GUIs well. I prefer the use of a Supervising Controller which you can read about here. The reason for this is that I believe automated tests are one of the most important tools you have. The more you can automate the better off you are. The supervising presenter pattern makes the forms a thin shell so there is very little that can't be tested automatically.

Sorry to say it, but it seems you have mess in your head trying to improve your coding too much in one step.
There is no way to answer your question as such, but here we go.
First start with OOP, think about what objects are required for your game/GUI and start implementing them a little at a time, see if there are chances to break up these objects further, or perhaps reunite some objects that make no sense on their own, then try to figure out if you have repeated functionality among your objects, if you do, figure out if this repeated functionality is a (or many) base class or not.
Now this will take you a few days, or weeks to really grok it well, then worry about dividing your logic and rendering.

I have some tutorials that are written in C#. It discusses this very same topic. It is a starting point for a RogueLike game.
Object Oriented Design in C# Converting Legacy Game
Object Oriented Design: Domain Type Objects
Object Oriented Design: Rethinking Design Issues
BROKEN LINK - Object Oriented Design: Baby Steps in Acceptance Testing