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I can't access an instance variable in an if statement in Java

I am trying to simplify the Javax swing graphics classes in order to make it easier for other people to get into Java graphics, but I am facing a problem with testing it.
Keep in mind, that I am writing the main method as a user of the code and not the developer. I need answers that will change the code of the class methods and not the main method.
What my main method code is supposed to do is print 'hovering' when the user hovers over the button. However, when I add a SOP statement before the if statement, it works...
The method for the mouse hovering is in the Button class.
Here is my main method code -
public static void main(String[] args) {
GraphWin win = new GraphWin(1000, 1000, "Graphics Window - Test");
win.show();
Button button = new Button(new Point(380, 300), new Point(620, 400));
button.draw(win);
enter code herewhile(true) {
//System.out.println(button.hovering);
if(button.hovering) {
System.out.println("hovering");
}
}
}
And here is my code for the Button class -
public class Button implements MouseListener{
public JButton button;
public boolean clicked = false, hovering = false, pressed = false;
public Button(Point p, Point p2) { //This is the default constructor of the button with only 2 points specified
this.button = new JButton();
this.setBounds(p, p2);
this.button.addMouseListener(this);
this.setBorderVisible(false);}
public Button(Point p, Point p2, String text) { //This constructor requires text to be displayed`enter code here`
this.button = new JButton(text);
this.setBounds(p, p2);
this.button.addMouseListener(this);
this.setBorderVisible(false);}
public Button(String icon, Point p, Point p2) { //This constructor sets an Icon for the button
this.button = new JButton();
this.setIcon(icon);
this.setBounds(p, p2);
this.button.addMouseListener(this);
this.setBorderVisible(false);}
public Button(Point p, Point p2, String text, String icon) { //Here, both the text and Icon is specified
this.button = new JButton(text);
this.setIcon(icon);
this.setBounds(p, p2);
this.button.addMouseListener(this);
this.setBorderVisible(false);}
public void draw(GraphWin win) {
win.window.add(this.button);}
public void setBounds(Point p, Point p2) {
this.button.setBounds(p.x, p.y, p2.x - p.x, p2.y - p.y);
}
public void setEnabled(boolean enable) {
this.button.setEnabled(enable);}
public void disable() {
this.button.setEnabled(false);}
public void enable() {
this.button.setEnabled(true);
}
public void setColor(Color color) {
this.button.setBackground(color);}
public void setColor(String color) {
this.button.setBackground(Color.decode(color));}
public void setText(String text) {
this.button.setText(text);}
public void setIcon(String icon) {
File imageCheck = new File(icon);
if(!imageCheck.exists())
System.out.println("Image file not found!");
else
this.button.setIcon(new ImageIcon(icon));
}
public void resizeIcon(String icon, int width, int height) {
Image img = new ImageIcon(icon).getImage();
img = img.getScaledInstance(width, height, Image.SCALE_SMOOTH);
this.button.setIcon(new ImageIcon(img));
}
public void setCustomMargins(int top, int bottom, int left, int right) {
this.button.setMargin(new Insets(top, left, bottom, right));}
public void setMargins(int m) {
this.button.setMargin(new Insets(m, m, m, m));}
public void setLabel(String label) {
this.button.setToolTipText(label);
}
public void setBorderVisible(boolean border) {
this.button.setBorderPainted(border);}
public void setOpaque(boolean opaque) {
this.button.setContentAreaFilled(opaque);}
#Override
public void mouseEntered(MouseEvent arg0) {
this.hovering = true;
System.out.println(1);
}
#Override
public void mouseExited(MouseEvent arg0) {
this.hovering = false;
}
#Override
public void mousePressed(MouseEvent arg0) {
this.pressed = true;
}
#Override
public void mouseReleased(MouseEvent arg0) {
this.pressed = false;
}
#Override
public void mouseClicked(MouseEvent e) {
this.clicked = true;
System.out.println(1);
}
}

This sort of thing is usually to do with threading.
Events in Swing are dispatched on the AWT Event Dispatch Thread (EDT). In order to be thread-safe, practically everything dealing with Swing/AWT should be done on the EDT.
In your case, there is no kind of locking between the variable being set and read. Adding a println causes a pause (with all sorts of memory barriers or whatnot) that happens to allow the program to run in the desired sequence.
You've probably seen main methods written to pass execution straight over to the AWT.
class MyGUI {
public static void main(String[] args) {
java.awt.EventQueue.invokeLater(MyGUI::go);
}
private static void go() {
...
It might be better to supply the main class yourself, implemented such that it takes the application class as an argument and passes execution on once everything is setup. Whilst traditionally command lines use a main static method/function, everywhere else subtypes: Applets, Servlets, etc.

best approach would be to use a isHovering() method but educated guess on the behavior inside a while(true) with or without a Sysout might be related to a compiler optimisation. Might be fixed by putting the hovering variable as transient

libgdx Timer countdown implmentation

I want to create efficienty timer in LibGDX framework, that will count the time left for my character. The doSmth() method should be called as many times as some flag is set to true. I know that the third parametr of Timer is that, how many times should it trigger. For now one Im calling the method recursive, but I dont think it is the efficient way.
public void updateTimer(){
new Timer().scheduleTask(new Timer.Task() {
#Override
public void run() {
doSmth();
updateTimer();
}
},1);
}

It would be more accurate to use a repeat count. Your method will introduce a bit of error each time the task is run, because the task is run on the GL thread, so it will occur just slightly after one second, but you are repeating it one second after that. So with each repeat you are slightly further behind.
private Timer.Task myTimerTask = new Timer.Task() {
#Override
public void run() {
doSmth();
}
};
public void startTimer(){
Timer.schedule(myTimerTask, 1f, 1f);
}
And when you need to stop it:
myTimerTask.cancel();

The com.badlogic.gdx.utils.Timer executes tasks in the future on the main loop thread,even if your game is in a pause screen, a menu or in another state, you can simply control time in the render method by adding delta time.
private float timeSeconds = 0f;
private float period = 1f;
public void render() {
//Execute handleEvent each 1 second
timeSeconds +=Gdx.graphics.getRawDeltaTime();
if(timeSeconds > period){
timeSeconds-=period;
handleEvent();
}
[...]
}
public void handleEvent() {
[...]
}
To keep organized i personally have an array on my main game class that holds all my timed events and process everything on the render cycle. In your case you can put some control variables as you wish.
my implementation example:
// MainGame.java
private ObjectMap<TimedEventEnum, TimedEvent> hshTimedEvent;
public void render(){
executeTimedEvents();
}
private void executeTimedEvents() {
for (ObjectMap.Entry<TimedEventEnum, TimedEvent> entry : hshTimedEvent) {
TimedEvent event = entry.value;
event.process();
}
}
public void killEvent(TimedEventEnum event) {
hshTimedEvent.remove(event);
}
// TimedEventEnum.java
public enum TimedEventEnum {
COUNT_MONEY,
CHECK_FOR_ACHIEVS,
ANOTHER_EVENT_EXAMPLE
}
//CountMoneyTimedEvent.java
public class CountMoneyTimedEvent extends Timer implements TimedEvent {
public CountMoneyTimedEvent() {
super();
init(this, 4f, false);
}
#Override
public void execute() {
//execute logic here
}
#Override
public void reset() {
this.timesFired = 0L;
}
}
//Timer.java
public abstract class Timer {
private Float deltaCount;
private Float timeToEvent;
private Boolean isRepeatable;
protected Long timesFired;
private TimedEvent event;
Timer() {
}
public void init(TimedEvent event, Float eventTime, Boolean isRepeatable) {
this.deltaCount = 0f;
this.timeToEvent = eventTime;
this.isRepeatable = isRepeatable;
this.timesFired = 0L;
this.event = event;
}
public void process() {
if (isEventTime()) {
event.execute();
}
}
private Boolean isEventTime() {
if (event != null && (isRepeatable || timesFired == 0)) {
deltaCount += Gdx.graphics.getRawDeltaTime();
if (deltaCount > timeToEvent) {
deltaCount -= timeToEvent;
timesFired++;
return true;
}
}
return false;
}
protected void executeNextEvent() {
deltaCount = timeToEvent;
}
}
// TimedEvent.java
public interface TimedEvent {
void execute();
void reset();
void process();
}

Query on creating separate thread in java?

Below is the compiled program replica of actual problem code,
import javax.swing.JOptionPane;
import javax.swing.SwingUtilities;
public class Dummy {
public static boolean getUserCheck(int size, boolean Check) {
if (Check) {
int ret = JOptionPane.showConfirmDialog(null, size + " entries, Yes or no?",
"Warning", 0);
if (ret > 0) {
System.out.println("User said No: " + ret);
return false;
} else if (ret <= 0) {
System.out.println("user said Yes: " + ret);
return true;
}
}
return true;
}
public static void workerMethod1() {
System.out.println("am worker method 1");
}
public static void workerMethod2() {
System.out.println("am worker method 2");
}
public static void main(String[] args) {
System.out.println("mainthread code line 1");
int size = 13;
boolean thresholdBreach = true;
if (getUserCheck(size, thresholdBreach)) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
workerMethod1();
}
});
SwingUtilities.invokeLater(new Runnable() {
public void run() {
workerMethod2();
}
});
}
System.out.println("mainthread code line 2");
System.out.println("mainthread code line 3");
}
}
where i would like to run the if{} block in main() on separate thread. Because these 2 lines,
System.out.println("mainthread code line 2");
System.out.println("mainthread code line 3");
need not wait for completion of if(){} block
Another problem is, experts recommend to run confirm-dialog methods on event thread.
int ret = JOptionPane.showConfirmDialog(null, size + " entries, Yes or no?",
"Warning", 0);
Please help me!!!!

JOptionPane is a Swing method and should be called on the EDT, the Event Dispatch Thread, and only on this thread, and so it suggests that all your code above should be on the EDT, and that most of your SwingUtilities.invokeLater(new Runnable() calls are completely unnecessary. The only necessary ones will be the main one, where you launch your Swing GUI code, and any areas where Swing calls need to be made from within background threads. Again, if any of the above code is being made within background threads, then the JOptionPane should not be in that thread.
For more specific information in this or any other answer, please provide more specific information in your question. Let's end all confusion. The best way to get us to fully and quickly understand your problem would be if you were to to create and post a minimal example program, a small but complete program that only has necessary code to demonstrate your problem, that we can copy, paste, compile and run without modification.
I have a sneaking suspicion that a decent refactoring along MVC lines could solve most of your problems. Your code is very linear with its lines of code that must follow one another and its if blocks, and it is also tightly coupled with your GUI, two red flags for me. Perhaps better would be less linear code, more event and state-driven code, code where your background code interacts with the GUI via observer notification, and where the background code likewise responds to state changes in the GUI from control notification.
Your control needs two SwingWorkers, one to get the row count and the other to get the rest of the data if the user decides to do so. I'd add a PropertyChangeListener to the first SwingWorker to be notified when the row count data is ready, and then once it is, present it to the view for the user to select whether or not to proceed. If he decides to proceed, I'd then call the 2nd SwingWorker to get the main body of the data.
For example, a rough sketch of what I'm talking about:
import java.awt.Dialog.ModalityType;
import java.awt.Dimension;
import java.awt.Window;
import java.awt.event.ActionEvent;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.concurrent.ExecutionException;
import javax.swing.*;
#SuppressWarnings("serial")
public class SwingWorkerFooView extends JPanel {
private static final int PREF_W = 400;
private static final int PREF_H = 300;
private JProgressBar progressBar;
private JDialog dialog;
public SwingWorkerFooView() {
add(new JButton(new ButtonAction("Foo", this)));
}
#Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet()) {
return super.getPreferredSize();
}
return new Dimension(PREF_W, PREF_H);
}
public boolean showOptionGetAllData(int numberOfRows) {
String message = "Number of rows = " + numberOfRows + ". Get all of the data?";
String title = "Get All Of Data?";
int optionType = JOptionPane.YES_NO_OPTION;
int result = JOptionPane.showConfirmDialog(this, message, title, optionType);
return result == JOptionPane.YES_OPTION;
}
public void showProgressBarDialog() {
progressBar = new JProgressBar();
progressBar.setIndeterminate(true);
Window window = SwingUtilities.getWindowAncestor(this);
dialog = new JDialog(window, "Hang on", ModalityType.APPLICATION_MODAL);
JPanel panel = new JPanel();
panel.add(progressBar);
dialog.add(panel);
dialog.pack();
dialog.setLocationRelativeTo(this);
dialog.setVisible(true);
}
public void closeProgressBarDialog() {
dialog.dispose();
}
private static void createAndShowGui() {
JFrame frame = new JFrame("SwingWorkerFoo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new SwingWorkerFooView());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
#SuppressWarnings("serial")
class ButtonAction extends AbstractAction {
Workers workers = new Workers();
private SwingWorker<Integer, Void> firstWorker;
private SwingWorker<List<String>, Void> secondWorker;
private SwingWorkerFooView mainGui;
public ButtonAction(String name, SwingWorkerFooView mainGui) {
super(name);
this.mainGui = mainGui;
}
#Override
public void actionPerformed(ActionEvent e) {
firstWorker = workers.createFirstWorker();
firstWorker.addPropertyChangeListener(new FirstPropertyChangeListener());
firstWorker.execute();
mainGui.showProgressBarDialog();
}
private class FirstPropertyChangeListener implements PropertyChangeListener {
#Override
public void propertyChange(PropertyChangeEvent evt) {
if (evt.getNewValue() == SwingWorker.StateValue.DONE) {
mainGui.closeProgressBarDialog();
try {
int numberOfRows = firstWorker.get();
boolean getAllData = mainGui.showOptionGetAllData(numberOfRows);
if (getAllData) {
secondWorker = workers.createSecondWorker();
secondWorker.addPropertyChangeListener(new SecondPropertyChangeListener());
secondWorker.execute();
mainGui.showProgressBarDialog();
} else {
// user decided not to get all data
workers.cleanUp();
}
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
}
}
}
private class SecondPropertyChangeListener implements PropertyChangeListener {
#Override
public void propertyChange(PropertyChangeEvent evt) {
if (evt.getNewValue() == SwingWorker.StateValue.DONE) {
mainGui.closeProgressBarDialog();
try {
List<String> finalData = secondWorker.get();
// display finalData in the GUI
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
}
}
}
}
class Workers {
// database object that may be shared by two SwingWorkers
private Object someDataBaseVariable;
private Random random = new Random(); // just for simulation purposes
private class FirstWorker extends SwingWorker<Integer, Void> {
#Override
protected Integer doInBackground() throws Exception {
// The Thread.sleep(...) is not going to be in final production code
// it's just to simulate a long running task
Thread.sleep(4000);
// here we create our database object and check how many rows there are
int rows = random.nextInt(10 + 10); // this is just for demonstration purposes only
// here we create any objects that must be shared by both SwingWorkers
// and they will be saved in a field of Workers
someDataBaseVariable = "Fubar";
return rows;
}
}
private class SecondWorker extends SwingWorker<List<String>, Void> {
#Override
protected List<String> doInBackground() throws Exception {
// The Thread.sleep(...) is not going to be in final production code
// it's just to simulate a long running task
Thread.sleep(4000);
List<String> myList = new ArrayList<>();
// here we go through the database filling the myList collection
return myList;
}
}
public SwingWorker<Integer, Void> createFirstWorker() {
return new FirstWorker();
}
public void cleanUp() {
// TODO clean up any resources and database stuff that will not be used.
}
public SwingWorker<List<String>, Void> createSecondWorker() {
return new SecondWorker();
}
}
The key to all of this is to not to think in a linear console program way but rather to use observer design pattern, i.e., listeners of some sort to check for change of state of both the GUI and the model.
It's essentially:
create worker
add observer to worker (property change listener)
execute worker
show progress bar dialog or notify user in some way that worker is executing.
The listener will be notified when the worker is done, and then you can query the worker (here via the get() method call) as to its end result.
Then the progress dialog can be closed
And the view can display the result or get additional information from the user.

Yes; SwingUtilities.invokeLater() simply places your runnable on the AWT event queue to be processed later, and it is safe to do so at any time.

Strange Concurrency Issue in Java Swing

I have a Jframe which is my application's window (appFrame in the following code) that contains a lot of logic and takes like 1 second or so to load. In the meantime I want to show my user a very nice loading frame (initFrame). However, when I run this code, the initFrame does appear but the text in a JLabel on it doesn't appear immediately - it actually doesn't appear at all in the brief moment till the app frame is loaded.
If i comment out all the appFrame, and only launch the initFrame, the text is loaded instantly, no waiting time at all. Why is this so? Might this be a concurrency issue?
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() { //as per best practice for concurrency in swing - see http://docs.oracle.com/javase/tutorial/uiswing/concurrency/
#Override
public void run() {
final JFrame initFrame = new InitFrame();
initFrame.setVisible(true);
final AppFrame appFrame = new AppFrame();
appFrame.setVisible(true);
initFrame.setVisible(false);
initFrame.dispose();
}
});
}

I would separate the frames' creation into two threads. The first, initializing InitFrame. Running this thread and calling isShowing() on the InitFrame object. When it returns true, run the second thread to initialize and show AppFrame.
This will force a happens before relationship between the visibility of the two frames.
class Main {
JFrame initFrame = null;
AppFrame appFrame = null;
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
initFrame = new InitFrame();
initFrame.setVisible(true);
}
});
while(!initFrame.isShowing()) {
try {
Thread.sleep(50);
} catch (InterruptedException e) {
}
}
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
appFrame = new AppFrame();
appFrame.setVisible(true);
initFrame.setVisible(false);
initFrame.dispose();
}
});
}
}

Here's an example of what might be going wrong in your AppFrame.
You can run the test with threading:
java SplashTest true
or without
java SplashTest
When threading is enabled, you see the SplashFrame and AppFrame updating every 250ms, more or less.
When threading is not enabled, you get to see the SplashFrame with no components showing, the app 'hangs' for 4 seconds, then you see the AppFrame.
The example is somewhat contrived, but might give you some ideas.
Note that the SplashFrame has no 'direct' connection to the AppFrame. All communication is through the AppFrameWorkListener interface.
I've also put the 'work' in the AppFrame. But really if there is a lot of processing to be done it should be extracted out of the UI code, run in a separate Thread, and the AppFrame would be notified of progress by the task, in the same way as the SplashFrame currently is.
import javax.swing.*;
class SplashTest {
static boolean useThread = false;
public static void main(String[] args) {
// Pass true at the command line to turn on threading.
// No args, or any value other than true will turn off threading.
if (args.length > 0) {
useThread = new Boolean(args[0]);
}
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
SplashFrame splashFrame = new SplashFrame();
splashFrame.setVisible(true);
new AppFrame(splashFrame).setVisible(true);
}});
}
private static class BaseFrame extends JFrame {
public BaseFrame() {
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
setSize(200, 200);
setTitle(getClass().getSimpleName());
}
}
private static class SplashFrame extends BaseFrame implements AppFrameWorkListener {
JLabel status;
public SplashFrame() {
setLocation(0, 0);
status = new JLabel("Splash Frame");
getContentPane().add(status);
}
public void appFrameWorkStart() {
status.setText("Work started");
}
public void appFrameWorkProgress(long timeElapsed) {
status.setText("Work has taken " + timeElapsed + "ms so far");
}
public void appFrameWorkDone() {
// http://stackoverflow.com/questions/1234912/how-to-programmatically-close-a-jframe
setVisible(false);
dispose();
}
}
private static class AppFrame extends BaseFrame {
JLabel status;
AppFrameWorkListener listener;
public AppFrame(AppFrameWorkListener listener) {
setLocation(200, 200);
status = new JLabel("App Frame");
getContentPane().add(status);
this.listener = listener;
// None of this 'heavy lifting' should be in a constructor.
if (useThread) {
new Thread(new Runnable() {
#Override
public void run() {
doLotsOfWork(4);
}
}).start();
} else {
doLotsOfWork(4);
onWorkDone();
}
}
private void doLotsOfWork(int workLengthSeconds) {
// We're starting. Ensure onWorkStart is called on the EDT,
// as this method may be called from a different Thread.
invokeOnWorkStartOnEDT();
long start = System.currentTimeMillis();
// Hammer the CPU for "workLengthSeconds" number of seconds.
// And do some contrived progress reporting.
long workLengthMs = workLengthSeconds * 1000;
while (System.currentTimeMillis() - start < workLengthMs) {
long innerStart = System.currentTimeMillis();
// Consume 250ms CPU before issuing progress update.
while (System.currentTimeMillis() - innerStart < 250);
invokeOnWorkProgressOnEDT(System.currentTimeMillis() - start);
}
// We're done now. Ensure onWorkDone is called on the EDT,
// as this method may be called from a different Thread.
invokeOnWorkDoneOnEDT();
}
private void invokeOnWorkStartOnEDT() {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
onWorkStart();
}
});
}
private void invokeOnWorkProgressOnEDT(final long timeElapsed) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
onWorkProgress(timeElapsed);
}
});
}
private void invokeOnWorkDoneOnEDT() {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
onWorkDone();
}
});
}
private void onWorkStart() {
status.setText("Work Started");
if (null != listener) {
// Tell someone who's interested in the work status.
listener.appFrameWorkStart();
}
}
private void onWorkProgress(long timeElapsed) {
status.setText("Work has taken " + timeElapsed + "ms so far");
if (null != listener) {
// Tell someone who's interested in the work status.
listener.appFrameWorkProgress(timeElapsed);
}
}
private void onWorkDone() {
status.setText("Work Done");
if (null != listener) {
// Tell someone who's interested in the work status.
listener.appFrameWorkDone();
}
}
}
interface AppFrameWorkListener {
public void appFrameWorkDone();
public void appFrameWorkStart();
public void appFrameWorkProgress(long timeElapsed);
}
}

You Should use Java Thread and you can show an interactive Splash Screen (Custom made) to your user in the mean while while your code is generating whatever you want here is a tutorial just take a look
You should use Threads for good and efficient concurrency thats it

Access static variable from another class

I have two classes in same package. i have declared a static variable in one class and want to access that variable in another class.
Here is my code in which i have declared the static variable
public class wampusGUI extends javax.swing.JFrame {
static String userCommand;
public wampusGUI() {
initComponents();
}
public void setTextArea(String text) {
displayTextArea.append(text);
}
private void enterButtonActionPerformed(java.awt.event.ActionEvent evt) {
userCommand = commandText.getText();
}
public static void main(String args[]) {
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
wampusGUI w = new wampusGUI();
w.setVisible(true);
Game g = new Game(w);
g.play();
}
});
}
}
Here is the code in which i want to access variable
public class Game {
private wampusGUI gui;
public Game(wampusGUI w) {
world = new World();
world.start();
gui = w;
}
public void play() {
gui.setTextArea(welcome());
gui.setTextArea(describe());
for (;;) {
String s = userCommand; // here value should come should
System.out.println(userCommand);
Command c = Command.create(s);
String r = c.perform(world);
// is game over?
if (r == null) {
break;
}
System.out.println(r);
}
System.out.println("Game over");
}
}
However, i can pass the variable from first class as a argument. but the problem is that, when i will run program the value is going null first time, which i dont want. i want when i enter value in textfield then it should go to another class.
Thank you.

Looking at your code, it seems you want to show dialogs to your user with a certain text
gui.setTextArea(welcome());
gui.setTextArea(describe());
and sometimes, that dialog should capture user input which is handled afterwards.
Those setTextArea calls are not what you want to use. The user will never see the welcome message as it will immediately be replaced by the describe message.
Make sure you do not block the Event Dispatch Thread (EDT) or nothing will be shown at all. I do not know what your Command class will do, but I see an infinite loop on the Event Dispatch Thread which is never a good thing. Take a look at the Concurrency in Swing tutorial for more information
Thanks to that for loop, the user will simply not be capable to input any command as the EDT is busy handling your loop. What you need is a blocking call allowing the user to provide input (not blocking the EDT, but just blocking the execution of your code). The static methods in the JOptionPane class are perfectly suited for this (e.g. the JOptionPane#showInputDialog). These methods also have a mechanism to pass the user input back to the calling code without any static variables, which solves your problem.

I suggest that you use a listener of one sort or another to allow the Game object to listen for and respond to changes in the state of the GUI object. There are several ways to do this, but one of the most elegant and useful I've found is to use Swing's own innate PropertyChangeSupport to allow you to use PropertyChangeListeners. All Swing components will allow you to add a PropertyChangeListener to it. And so I suggest that you do this, that you have Game add one to your WampusGUI class (which should be capitalized) object like so:
public Game(WampusGUI w) {
gui = w;
gui.addPropertyChangeListener(new PropertyChangeListener() {
// ....
}
This will allow Game to listen for changes in the gui's state.
You'll then want to make the gui's userCommand String a "bound property" which means giving it a setter method that will fire the property change support notifying all listeners of change. I would do this like so:
public class WampusGUI extends JFrame {
public static final String USER_COMMAND = "user command";
// ....
private void setUserCommand(String userCommand) {
String oldValue = this.userCommand;
String newValue = userCommand;
this.userCommand = userCommand;
firePropertyChange(USER_COMMAND, oldValue, newValue);
}
Then you would only change this String's value via this setter method:
private void enterButtonActionPerformed(java.awt.event.ActionEvent evt) {
setUserCommand(commandText.getText());
}
The Game's property change listener would then respond like so:
gui.addPropertyChangeListener(new PropertyChangeListener() {
#Override
public void propertyChange(PropertyChangeEvent pcEvt) {
// is the property being changed the one we're interested in?
if (WampusGUI.USER_COMMAND.equals(pcEvt.getPropertyName())) {
// get user command:
String userCommand = pcEvt.getNewValue().toString();
// then we can do with it what we want
play(userCommand);
}
}
});
One of the beauties of this technique is that the observed class, the GUI, doesn't have to have any knowledge about the observer class (the Game). A small runnable example of this is like so:
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import javax.swing.*;
public class WampusGUI extends JFrame {
public static final String USER_COMMAND = "user command";
private String userCommand;
private JTextArea displayTextArea = new JTextArea(10, 30);
private JTextField commandText = new JTextField(10);
public WampusGUI() {
initComponents();
}
private void setUserCommand(String userCommand) {
String oldValue = this.userCommand;
String newValue = userCommand;
this.userCommand = userCommand;
firePropertyChange(USER_COMMAND, oldValue, newValue);
}
private void initComponents() {
displayTextArea.setEditable(false);
displayTextArea.setFocusable(false);
JButton enterButton = new JButton("Enter Command");
enterButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent evt) {
enterButtonActionPerformed(evt);
}
});
JPanel commandPanel = new JPanel();
commandPanel.add(commandText);
commandPanel.add(Box.createHorizontalStrut(15));
commandPanel.add(enterButton);
JPanel mainPanel = new JPanel();
mainPanel.setLayout(new BorderLayout());
mainPanel.add(new JScrollPane(displayTextArea));
mainPanel.add(commandPanel, BorderLayout.SOUTH);
add(mainPanel);
}
public void setTextArea(String text) {
displayTextArea.append(text);
}
private void enterButtonActionPerformed(java.awt.event.ActionEvent evt) {
setUserCommand(commandText.getText());
}
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
WampusGUI w = new WampusGUI();
w.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
w.pack();
w.setLocationRelativeTo(null);
w.setVisible(true);
Game g = new Game(w);
g.play();
}
});
}
}
class Game {
private WampusGUI gui;
public Game(WampusGUI w) {
gui = w;
gui.addPropertyChangeListener(new PropertyChangeListener() {
#Override
public void propertyChange(PropertyChangeEvent pcEvt) {
// is the property being changed the one we're interested in?
if (WampusGUI.USER_COMMAND.equals(pcEvt.getPropertyName())) {
// get user command:
String userCommand = pcEvt.getNewValue().toString();
// then we can do with it what we want
play(userCommand);
}
}
});
}
public void play() {
gui.setTextArea("Welcome!\n");
gui.setTextArea("Please enjoy the game!\n");
}
public void play(String userCommand) {
// here we can do what we want with the String. For instance we can display it in the gui:
gui.setTextArea("User entered: " + userCommand + "\n");
}
}

I agree with Jon Skeet that this is not a good solution...
But in case u want an dirty solution to ur problem then u can try this:
public class wampusGUI extends javax.swing.JFrame
{
private static wampusGUI myInstance;
public wampusGUI( )
{
myInstance = this;
initComponents();
}
public static void getUserCommand()
{
if(myInstance!=null)
{
return myInstance.commandText.getText();
}
else
{
return null;
}
}
......
......
}
in the other class use:
public void play()
{
.....
//String s = userCommand; // here value should come should
String s = wampusGUI.getUserCommand();
.....
}
This kind of code is there in some of our legacy projects... and I hate this.