Develop Reference

visualizing JPanel change within a loop

I am new to Java swing programming. I want to make a frame which will appear red and blue in turn one after another. So, I took 2 child JPanel, 1 for red and other for blue, and a for-loop. On each iteration I remove one panel from parent panel and add another. But, when I run the program it only shows the last state of the frame.
Can anyone explain why? And what's the intended approach to make a program work like that?
My code:
public class Test2 extends JFrame {
public Test2() {
JPanel Red = new JPanel(new BorderLayout());
JPanel Blue = new JPanel(new BorderLayout());
//...initialize Red and Blue
Red.setBackground(Color.red);
Blue.setBackground(Color.blue);
Red.setPreferredSize(new Dimension(200,200));
Blue.setPreferredSize(new Dimension(200,200));
JPanel panel = new JPanel(new BorderLayout());
panel.setPreferredSize(new Dimension(200,200));
add(panel);
pack();
setTitle("Border Example");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocationRelativeTo(null);
int M = 1000000; //note that, I made a long iteration to not finish the program fast and visualize the effect
for(int i=0;i<M;i++)
{
if(i%(M/10)==0) System.out.println(i); //to detect whether the program is running
if(i%2==0)
{
panel.removeAll();
panel.repaint();
panel.revalidate();
panel.add(Red,BorderLayout.CENTER);
}
else
{
panel.removeAll();
panel.repaint();
panel.revalidate();
panel.add(Blue,BorderLayout.CENTER);
}
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
Test2 ex = new Test2();
ex.setVisible(true);
}
});
}}

Don't use a loop. Swing will only repaint the frame once the entire loop has finished executing.
Instead you need to use a Swing Timer. When the Timer fires you invoke your logic. Read the section from the Swing tutorial on How to Use Swing Timers.
Here is a simple example of a Timer that simply displays the time every second: Update a Label with a Swing Timer
Also, don't remove/add panels. Instead you can use a Card Layout and sway the visible panel. Again read the tutorial on How to Use CardLayout.

Basically you don't need to use a while (or any other) loop, Swing only paints once it has finished that loop then repaint the GUI.
As stated before by #camickr on his answer, you could try a Swing Timer; here's an example that does exactly what you want.
From your comment on another answer:
Could you please explain why "repaint" does not work in a loop? And why is the Timer working without a "repaint"?
Swing is smart enough to know it doesn't needs to repaint in a loop, instead it will repaint once it the loop finishes, if you read the tutorial on Swing Custom Paint on the step 3 it says:
"Swing is smart enough to take that information and repaint those sections of the screen all in one single paint operation. In other words, Swing will not repaint the component twice in a row, even if that is what the code appears to be doing."
And Timer will repaint it, because it's not running on the EDT but in it's own Thread

I would suggest to take in one step at a time.
First make it run without changing panels / colors.
Now it doesn't because this
public final void Test2() {
is a method (which is never used) and not a constructor.
Change to a constructor declaration like :
public Test2() {
to make the program do something. Then you can go to the next step.
Also use Java naming conventions (like blue instead of Blue).

JComboBox is refering to old Frame while removeAllItems()

I tried to figure this out myself but I can't. I'm stuck at a strange problem.
I have a Java Program with multiple classes and forms (I use Intellij and the build in GUI-Creator). When I switch from one Screen to another I just call frame.setVisible(false); at the leafing window and frame.setVisible(true); at the window I want to show next.
On a Button Click I make this:
In Class 1:
if (e.getSource() == umschaltenButton) {
this.mainW.goToMainWindow();
logger.log(Level.INFO, "Switched Back to MainMenu");
frame.setVisible(false);
}
And here is the weird part.
In Class 2:
public void goToMainWindow() {
frame = tvElectronics.drawMainWindow(); // I get a new Frame with new Images and so on
frame.addMouseListener(al);
frame.add(BotomPanel); // in here is the JComboBox
frame.setSize(LENGTH, HEIGHT);
comboBox1.removeAllItems(); // Here it tryes to refere to the old frame before i made frame = tvElectronics.drawMainWindow();
Vector<String[]> content = tvElectronics.getContent();
for (int i = 0; i < tvElectronics.getAnz(); ++i) {
comboBox1.addItem((i + 1) + ". " + content.get(i)[3]);
}
comboBox1.setSelectedIndex(chanel);
frame.setVisible(true);
}
And so it tries to update the old frame from class2 which no longer exists because of the new one I just created. And so I have 2 frames open: one as I want it and one strange old frame form class2.
My problem is that I want bind my JComboBox to a new Frame and update it but it is still connected to the old one and that causes weird problems like jumping back in the function. I mean it is at the last line of goToMainWindow() and then it starts again at the first line.

First off you should avoid swapping JFrames as your program does since this is a very annoying GUI design. Please read The Use of Multiple JFrames, Good/Bad Practice? for more on this.
Next, it's impossible for us to tell what GUI view your JComboBox is associated with.
But having said that, it really shouldn't matter. Instead of doing what you're doing, I would give the display class that holds a JCombBox a public method that you call on the containing display class that clears the contained JComboBox's model or that places items in the model. This way, there will be no ambiguity as to which JComboBox you're referring to, and this way you avoid directly exposing a view's inner components.
As an aside, I try to gear my display or view classes towards creating JPanels, not JFrames as this will give my code much greater flexibility.
For example
// my display class
class Display1 {
private DefaultComboBoxModel<String> myModel = new DefaultComboBoxModel<>();
private JComboBox<String> myCombo = new JComboBox<>(myModel);
public void removeAllComboElements() {
myModel.removeAllElements();
}
public void addElement(String ele) {
myModel.addElement(ele);
}
}
Same for your Display2 class. Then you can call the correct method on the JComboBox that is held by the correct view/display.
This way, when you swap displays, perhaps by using a CardLayout, you can clear the JComboBox in the display that is being shown by calling its own method to clear its own combobox's model.

How to change make tabbed panels change on their own every few seconds?

I am currently learning Swing and am trying to create a simple program that stores information about different sports teams.
I have created multiple tabbed panels which all hold various information about each team. I would like to be able to have a button that when press displays each tabbed panel say every 10 seconds or so - sort of a slide show effect.
I have read up on action listeners but have not spent a lot of time on them as of yet so i am having trouble implementing this. I would be very grateful if anyone could maybe help me or just give me a push in the right direction. I have posted a snippet of code that i have atempted but i am at a loss about what to actually put inside the loop to achieve this.
slides.addActionListener(new ActionListener()
public void actionPerformed(ActionEvent actionEvent){
for(int i = 0; i<arrayList.size(); i++)
{
//code that changes the tabbed panels every few seconds.
}
}
});

I have created multiple tabbed panels which all hold various various information about each team.
Rather you should focus on creating a JPanel that can display team stats, and not so much JTabbedPanes. The JPanel can then be displayed in a JTabbedPane if desired.
I would use a CardLayout to swap JPanels, and then a Swing Timer to do the swapping. However if you use a single JPanel to display the stats, then you could even display one single JPanel and simply change the model (Team Stats information) that is displayed in it rather than swap JPanels.
As to what to put in your ActionListener, it will not be a for loop at all, but rather a Swing Timer, and you can read about it here: Swing Timer Tutorial.
e.g.,
slides.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent actionEvent){
int timerDelay = 10 * 1000; // 10 seconds
new Timer(timerDelay, new ActionListener() {
private int count = 0;
public void actionPerformed(ActionEvent evt){
if (count < maxCount) {
// code to show the team data for the count index
count++;
} else {
((Timer) evt.getSource()).stop(); // stop timer
}
}
}).start();
}
});

Can't play gif when using freeTTS Voices - Java

I am using freeTTS to speak out some text, in the background i want a animated gif to keep playing
When i try this: as soon as the voice starts speaking, the image in background gets hanged even if i keep it in some other JFrame... and after the speech is completed it starts moving. I want it to run properly without pauses.
I am placing a animated gif in a label by importing it to my application and changing the icon to that image in label' properties.
Edit
Here is my code:
private void RandomjBActionPerformed(java.awt.event.ActionEvent evt) {
Voice voice;
voice = voiceManager.getVoice(VOICENAME);
voice.allocate();
voice.speak("Daksh");
}
I am actually using a lot of setVisible, setText, declaration of integers, calculating on them but i have removed them to simplify the code for you to understand. Still it gives the same problem if executed.
The button 'RandomjB' is clicked from another button by the following code:
final Timer timer = new Timer(zad, new ActionListener() {
int tick = 0;
#Override
public void actionPerformed(ActionEvent e) {
System.out.println("Success" + ++tick);
RandomjB.doClick();
final int col = Integer.parseInt(t3.getText());;
if (tick >= col) {
((Timer) e.getSource()).stop();
for(int g=0; g<col; g++){
jButton2.setVisible(true); // Check Button -> Visible
}
}
}
});
timer.setInitialDelay(0);
System.out.format("About to schedule task.%n");
timer.start();
System.out.format("Task scheduled.%n");

It is hard to tell without the code, I however assume that you loop the speech synthesis within the one and only Swing-Thread and therefore block all kind of window updates as long as the speech loop is in progress.
As stated by Shaun Wild: you need to use a second Thread for the speech loop.

You may want to do some research on Threads and Concurrency
These allow two things to operate simultaneously, this is just my assumption.
Assuming that you instantiate some kind of class for the FreeTTS you may want to do something like this
FreeTTSClass tts;
new Thread(new Runnable(){
public void run(){
tts = new FreeTTSClass();
}
}).start();

Java Swing: Swing Worker, invokeAndWait and Overlapping JLabels

Hey guys I've come with 2 problems, both being Java Swing related. I am developing a card game in Java. I use arreays lists of type to hold the values of each card and I have a main Play() method that calls updates to the GUI using invokeLater and a Singleton approach to my GUI class.
The first question is fairly simple. I create the cards on the GUI using JLabels like so; attaching relevent listeners and adding them to the appropriate panel, in this case, the 'Human Hand Panel':
for (int i = 0; i < (HumanHand.size()); i++)
{
Card card = HumanHand.get(i);
BufferedImage cardImage = null;
try {
cardImage = ImageIO.read(new File("card/" + card + ".jpg"));
} catch (IOException e) {
e.printStackTrace();
}
JLabel picLabel = new JLabel(new ImageIcon( cardImage ));
picLabel.addMouseListener((MouseListener) me);
HumanHandDisplay.add(picLabel);
}
//HumanHandDisplay.validate();
HumanHandDisplay.updateUI();
The problem I'm having is that when the human hand is more than 7 cards or so, it creates a larger panel area and starts a new row of cards beneath. What I would like to do is, when the hand reaches a certain size, the cards start to overlap eachother (like you would hold cards in your hand). I've messed about with .validate() but gotten nowhere. Any help you can give here would be most welcome.
My second question is about using a Swing Worker to return the Human player's card selection. I have read a little bit about Swing workers but I'm unsure as to the best way to implement one in my own game. At present, using the console I have a scanner than takes the input of an int as the choice (the place of the specific card in the ArrayList). I would like this int to be selected by clicking on the card in the players hand. At the moment I use:
String name = "" + i;
picLabel.setName(name);
to set the names of the Card JLabels to the int in the for loop creating them (as shown^^), and I use:
public void mouseClicked(MouseEvent e) {
String name = ((JLabel)e.getSource()).getName();
System.out.println("Working " + name);
selection = Integer.parseInt(name);
}
To return that int when one of the cards is clicked. Here is what I've been using to call the GUI methods from Play() aswell:
SwingUtilities.invokeLater(new Runnable() {
public void run() {
GUI.getInstance().UpdateHand();
}
});
My question is, how can I get the Play method to call a method in the GUI class, which sets up the hand with the appropriate listeners (lets call it GUIPlayerSelection() for now) then wait for the player to click a card, which then returns the int to my Play() method in my main class that represents the card selected. I'm unsure as how to use invoke and wait, as in, if I use invoke and wait, will it just wait for the cards to be set up, or will it wait for the mouseClicked() method to finish aswell? Or will I have to do something else to make sure it waits for the mouse to be clicked after the hand set-up? And how then will I return that int? I've been told to use a swing worker but if someone could explain how I can implement that in this case that would be awesome.
Thank-you in advance.

For your first question, are you having an issue getting the frame to repaint or with the layout of the cards?
If the latter, then you may want to have a look at Java Layout Managers, it describes how the content pane inside your JFrame organizes the components added to it.
If none of those will work for you (and I don't think they will with that you describe), you can use the setBounds method to manually align your JLabels.