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Instead of getting two similar JFrames, I get one whith double component

I created a JFrame with buttons, labels and texts and I want to show it two times when I execute the main program, so I did like that:
import java.net.SocketException;
public class Main {
public static void main(String[] args) throws SocketException {
new MyFrame("client1");
new MyFrame("client2");
}
}
The result: I get two frames: one with the component of the other one inside, and one empty.
How to resolve this issue?

You are using static instance fields with your MyFrame for your components
A component can only reside within a single container, the moment you create your second frame, the static components are removed from the first container before been added to the second.
The solution, don't do this, ever...
I assume you are using static because you want to access these fields from another class, in that case, you should appropriate getters in the MyFrame class and pass a reference of it to those classes that need it.
Alternatively, you could establish a series of observers who monitor for changes and take appropriate action, this helps to decouple the code.
Personally, if you need to modify the MyFrame instances in some way, I'd provide setter methods that update your components instead, as I don't like exposing UI elements without good reason, to much opportunity for others to mess with them in appropriately

Correctly implementing the MVC pattern in GUI development using Swing in Java

Firstly, I come from a big PHP background with MVC, when I started with PHP, I browsed a lot of times, to try my best and perfect my MVC-Like design in PHP. A lot of people like answered with answers which helped me a lot.
But after starting GUI development in Swing, the answers about MVC in Swing are totally different. For instance, a model is also a view? According to Oracle's Suggestions TextElementModel doesn't have any logical business here, all it does is markup (set color etc) and setting data such as set text and so on. When I developed in PHP, there is no such thing as AbstractModel because I always got told that a model is not a class, or more, it's a whole layer that processes logical business.
In PHP I used Services, Data Mappers and Domain Objects, suggested from this amazing answer which helped me in PHP a lot: How should a model be structured in MVC?
My attempt
After reading again, I thought to give it a go and do a similar thing in Java:
I have the ControllerContainer which creates all controllers:
public class ControllerContainer {
private JFrame frame;
public ControllerContainer(JFrame rune) {
this.frame = frame;
}
public void initControllers() {
Atest test = new Atest(frame);
test.registerView("test", new ViewTest(test));
}
}
As you see, I add the view named "test" with instance of ViewTest to the controller, now it will be visible in the frame, and can take input.
My Controller class, which should be abstract, but I didn't make it abstract yet:
public class Controller {
private JFrame frame;
private Map<String, Component> views = new HashMap<String, Component>();
public Controller(JFrame frame) {
this.frame = frame;
}
protected void registerView(String title, Component c) {
this.views.put(title, c);
this.frame.add(c);
}
protected void deregisterView(String title) {
this.frame.remove(this.views.get(title));
this.views.remove(title);
}
protected Component getView(String title) {
return this.views.get(title);
}
}
And an test controller:
public class Atest extends Controller {
public Atest(JFrame frame) {
super(frame);
}
public void hit() {
((ViewTest) super.getView("test")).changeColorBlue();
}
}
And my TestView:
public class ViewTest extends JPanel {
private final Atest controller;
public ViewTest(Atest c) {
this.controller = c;
setBackground(Color.RED);
setLocation(0,0);
setSize(300, 300);
setLayout(null);
JButton b = new JButton("hello");
b.setSize(150, 150);
b.setLocation(0,0);
b.addMouseListener(new MouseListener() {
#Override
public void mouseClicked(MouseEvent arg0) {
controller.hit();
}
#Override
public void mouseEntered(MouseEvent arg0) {
}
#Override
public void mouseExited(MouseEvent arg0) {
}
#Override
public void mousePressed(MouseEvent arg0) {
}
#Override
public void mouseReleased(MouseEvent arg0) {
}
});
add(b);
}
public void changeColorBlue() {
setBackground(Color.BLUE);
}
}
The problem
As you see, my view creates a new button, and adds a mouse listener to it. the listener will have access to the controller to pass input. The controller gets the input and changes the view.
Basically the controller instantly forced to update the view, without any serious logical business because it's not needed in my case.
According to the link I have posted above, answered by tereško, how can I use his idea & suggestions with Java Swing correctly?
I am really confused, after the PHP background.
Maybe I am misunderstanding and everything should be done differently in different languages? But I thought that patterns should always be implemented the same way.
If you need more information, let me know.

MVC pattern it is a common paradigm, so there is no differences between pragramming languages in general.
However the implementation and some terminologies sometimes look different. In Java Swing it is often to see two following approaches:
1. Classic MVC
Controller - Listens user interface actions, performs corresponding Model updates. Can listen actions from different Views.
Model - Represents the state and the domain logic, methods to modify the state. Notifies listeners about the model updates (several Views can listen the updates). Model is independent and knows nothing about the listeners and their logic.
View - Responsible for user interface, UI elements layout, also listens Model updates and update the graphic inteface if required. Has some knowledge about the model, in example shown below it knows how to process list of "items".
Design of some simple "To Do" app can look like:
2. MVP (Model View Presenter)
Controller acts as a Mediator between the View and the Model. View become very thin and knows nothing about the Model and interact with Controller only. Controller listens both View and Model and perform corresponding actions.
Swing itself adds some confusion because it uses MVC pattern for its UI components. Each UI control has a Model and View. It makes easier to design new UI components, however in a "big picture" of the whole Application design - UI controls stay on the View layer.

Maybe I am misunderstanding, and everything should be done differently in different languages?
There is no misunderstanding; the pattern is merely applied differently.
As noted in a comment by #ordous and this this answer by #udalmik, a Swing application may have multiple implementations of the MVC pattern. As noted here and here, "not every interaction needs to pass through your application's controller." In contrast, a web application may well "have a 1:1 relation between views and controllers."
The Swing separable model architecture, cited here, "collapses the view and controller parts of each component into a single UI (user-interface) object." Swing controllers are scattered among the descendants of JComponent, typically in the component's UI delegate. As a concrete example, BasicButtonUI contains a BasicButtonListener that handles user mouse interaction.
Almost used the answer in the link, but the fact that his controller extends JPanel ruined it, totally confused me there.
This can be confusing, as a simple Swing program may have no explicit controller at all. As suggested in this outline, the controller has direct access to any relevant view and model; it may also listen to user interaction with the view. The example was intended to illustrate the simplest such interaction. It is mere coincidence that the effect is evoked by user interaction with a view component. The simulation cited here, for example, has a ControlPanel of view components that update the application's view and model. The DisplayPanel listens directly for a ComponentEvent that requires a model update. Etc.
Your application's controller is then free to focus on the application's needs.
#Marco13 elaborates on this and cites additional examples in this related answer.

How to interact with swing components in different classes

I'm just trying to figure some things out in my head about getting information to and from swing components from other classes.
I have a main class that uses a few classes to build a swing gui. How do I go about writing information to these components from another class. As far as I understand I need to use an arraylist to store references to these components but I'm not exactly sure how to do this, can someone please help me out?

I would suggest that you try to separate the model from the view. Don't store data relevant for the application logic in the actual GUI components.
Storing references to the components in an array list, and then access the data via the array list and various getText methods just seems like a bad idea to me.
Store the values in an object representing some model, and let the GUI reflect the state of the model.

This is one way of accessing another class's methods:
public class MyFrame extends JFrame implements ActionListener
{
private final MyBusinessClass bc = new MyBusnessClass();
#Override public void actionPerformed(ActionEvent e) {
this.bc.someBusinessMethod();
}
}

The Single Responsibility Principle and Event Listeners

I'm currently trying to develop a simple GUI notepad to increase my skills in OOP.
I stick to the Single Responsibility Principle while developing.
I've divided the application into several parts following the principle.
// This class runs the whole application
public class Notepad {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
new NotepadFrame();
}
});
}
}
// This class is responsible for setting up a frame
public class NotepadFrame extends JFrame {
public NotepadFrame() {
super("Notepad");
MenuBar menuBar = new MenuBar();
setJMenuBar(menuBar.createMenuBar());
pack();
setVisible(true);
}
}
// This class sets up a menu bar
public class MenuBar {
public JMenuBar createMenuBar() {
JMenuBar menuBar = new JMenuBar();
Buttons buttons = new Buttons();
menuBar.add(buttons.createFileMenuItems());
menuBar.add(buttons.createEditMenuItems());
menuBar.add(buttons.createFormatMenuItems());
menuBar.add(buttons.createHelpMenuItems());
return menuBar;
}
}
There are also the other classes.
Buttons - this class is used to create the buttons of the menu bar.
MenuItemActionListeners - this class handles all of the events fired by the buttons.
Have I divided the application in a correct way according to the Simple Responsibility Principle?
I'd also like to find out the best ways to handle action listeners, mouse listeners etc.
So far, I have used one actionPerformed(SomeEvent e) method to handle all of the events.
private JButton button;
private JButton button2;
public void actionPerformed(ActionEvent e) {
Object source = e.getSource();
if (source == button) {
} else if (source == button2) {
} // etc.
}
I realize this is the bad way of handling event listeners. As the application's size grows, adding so many conditional statements will make the code lest readable and the CPU performance will decrease.
How do you handle event listeners in your applications?
How would you write event listeners when developing huge and serious applications like MS Office or AutoCAD?

See How to Use Actions, which shows how Action "can be used to separate functionality and state from a component." Charles Bell's HTMLDocumentEditor is an example that shows how to reuse existing actions, as well as creating your own based on AbstractAction.

You are using one location where you handle all the events, which is a problem. In bigger applications you will handle events differently, different classes in your application will handle different events. Components listen to a few events only in which they are interested and not to all. For exmaple, a undo event makes sense to a paragraph object only and not to File object, a save event would make sense to the menu object and the document object.. etc.
Ideally, you classes would raise certain events and it will allow any other classes to subscribe to those events. Those subscribes are notified when an event occurs.
I would suggest you to look at the Observer Design Pattern.

I am very happy to see you want to use SRP while programming. The way you have done is perfectly acceptable. However, there is always a question on what level of these principles do you want to apply?
Also, in the code you provided (actionPerformed method), it is not OCP (Open Closed Principle) compliant and hence a bad design. Instead I would have separate methods for each type of event in each of those components that you have.
To keep the code DRY, you can have a method which tells you what to do when a component is selected. Delegate to this method from the several methods (due to different type of events) you associate for this component.
Hope this helps..

How to organize the controller of a MVC-based program with multiple screens/panels?

I'm currently working on a hobby project, written in Java, containing about two different JFrames with about 3-4 JPanels each. The problem I'm facing is that I'm not so sure how to handle the interaction with my controller and different view classes.
For instance, I've an article by Sun on Java App. design with MVC, where they list the option to let all the communications between model and view go through the controller as the most modern one, a tactic I've been taught as well and should do just fine. However, it doesn't quite go as deep as to explain how to handle all the ActionListeners involved for all the elements and different panels.
The 'way to go' I've been taught so far is to either use one controller and set the ActionListener to the various objects through getters and keep track of the active panel. The alternative my awesome Java book gives is to just stick to inner classes for each view class. Either method seems to result in pretty nasty code, while I'd prefer one or several controllers with as little bloat as possible.
My question of course is; how would you assign the ActionListeners as neatly and efficiently as possible while keeping the controller(s) usable?

Even though Markus' solution remains the neatest I've seen so far, I've made some slight changes, which are hopefully improvements in the eyes of the original author as well ;).
In case you add/remove an item of the list in response to an event, there is a chance of ending up with concurrent changes to the list; the event is handled, but the loop will continue in case there are more items after the one catching the event.
Therefore it's required to use a slightly different approach. I've decided to use the ListIterator.add() method, as this one supports modifications to the list while walking through its items. Possibly there are more elegant solutions available, but this one does the job pretty decent.
In case it will be of help to others; the modified code would similar be the following:
ListIterator<ActionListener> iterator = mActionListeners.listIterator();
public void actionPerformed(ActionEvent e)
{
iterator = mActionListeners.listIterator();
while (iterator.hasNext())
{
ActionListener actionListener = (ActionListener)iterator.next();
actionListener.actionPerformed(e);
}
}
public void addListener(ActionListener listener)
{
iterator.add(listener);
}
public void removeListener(ActionListener listener)
{
iterator.remove(listener);
}
In case there are better solutions or improvements I'll be glad to hear those as well.

The controller can implement ActionListener and contains a List of ActionListeners.
The controller you have to add to the The 3-4 top panels action listener.
Now you can add any ActionListener you want to the controller action listener list.
public void addListener(ActionListener listener)
{
mActionListeners.add(listener);
}
public void removeListener(ActionListener listener)
{
mActionListeners.remove(listener);
}
When the controller Action listener is called you have to call all action listener which are inside the controll list.
public void actionPerformed(ActionEvent e) {
List listeners = mActionListeners; // Edit 20090903
for (Iterator iterator = listeners .iterator(); iterator.hasNext();) {
ActionListener actionListener = (ActionListener)iterator.next();
actionListener.actionPerformed(e);
}
}