Develop Reference

I Have A Random Colour Program And I Need It To Rapidly Switch Through Colours

I have an ActionListener for my 'Aneurysm Mode' Button but when I press it, it does nothing...
Here is the code for the ActionListener:
private class AneurysmMode implements ActionListener {
AneurysmMode () {}
#Override
public void actionPerformed(ActionEvent e) {
while (true) {
try {
Thread.sleep(100);
frame.getContentPane().setBackground(colours[(int)(Math.random()*(9)+0)]);
}
catch (InterruptedException ex) {
}
}
}
}

You're sleeping the event dispatch thread, that's a bad idea. You will be adding the new colour to the event queue, but never actioning it because your button action listener doesn't return. If you take the while loop out of the button handler it should change every time the button is pressed.
A better option would be to change the colour in a timer action event and start the timer with a button press.

Unless you are making something sophisticated such as a game where you need much control over all the rendering. If not, you can make full use of javax.swing.timer instead of implementing your own rendering loop.
You should not apply the rendering loop or sleep in the EDT. The actions within actionPerformed is usually a "one-time" action.
Your actionPerformed in the button in this case works just like an "on/off" button, hence all you need to do is to turn on/off the timer (which controls the animation) when it is clicked:
class DrawingSpace extends JPanel{
private JButton button;
private Timer timer;
private int idx;
private Color[] colors;
public DrawingSpace(){
setPreferredSize(new Dimension(200, 200));
initComponents();
add(button);
}
public void initComponents(){
idx = 0;
colors = new Color[]{Color.RED, Color.YELLOW, Color.ORANGE, Color.MAGENTA, Color.BLUE, Color.CYAN, Color.GREEN};
button = new JButton("Let the colors rock!");
timer = new Timer(100, new ActionListener(){
#Override
public void actionPerformed(ActionEvent e){
//Change color every (approx) 100 milliseconds
idx = (idx + 1) % colors.length; //cycle through the colours
setBackground(colors[idx]);
}
});
button.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent e){
if(!timer.isRunning())
timer.start();
else
timer.stop();
}
});
}
}
A runner class to run the code:
class RainbowRunner{
public static void main(String[] args){
// Run the GUI code on the EDT
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame("Rainbow Frame");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new DrawingSpace());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
}

You would not want to throw the entire game loop (or whatever you call it) into your actionPerformed method. What you can do is, on every button click, trigger the timer if it is not started:
button.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent e){
if(!timer.isRunning())
timer.start();
else
timer.stop();
}
});
You may consider using a javax.swing.timer instead of writing your own loop.
In your javax.swing.timer, you can have something like this:
timer = new Timer(100, new ActionListener(){
#Override
public void actionPerformed(ActionEvent e){
//Change color every (approx) 100 milliseconds
idx = (idx + 1) % colours.length; //cycle through the colours
frame.setBackground(colours[idx]);
}
});

Firing delay between JFrame components

I want to show how merge sort perform visually using JFrame. What I want to do is to make visible subsequent JLabel with some time delay. I tried many way but all of them appears at same moment with no intermediate delay.
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
// jLabel1.setVisible(false);
jLabel2.setVisible(false);
jLabel3.setVisible(false);
jLabel4.setVisible(false);
jLabel5.setVisible(false);
jLabel6.setVisible(false);
jLabel7.setVisible(false);
final Timer t=new Timer((4000), null);
final int delay=2000;
final ActionListener taskPerformer = new ActionListener() {
public void actionPerformed(ActionEvent evt) {
jLabel1.setVisible(true);
t.getDelay();
jLabel2.setVisible(true);
t.setDelay(3000);
jLabel3.setVisible(true);
t.setDelay(2000);
jLabel4.setVisible(true);
t.setDelay(2000);
jLabel5.setVisible(true);
t.setDelay(2000);
jLabel6.setVisible(true);
t.setDelay(2000);
}
};
new Timer(delay, taskPerformer).start();
But when I click button all the lables appear at same momenet though I have kept delay.

You need to update the icons in the timer's action listener, as shown here. You can implement the Icon interface to render icons having a size proportional to an element's comparative value, as shown here.
Addendum: Can you please be little bit specific?
You want to animate the intermediate steps of sorting a List<Number> of size N in some initially random order. Number subclasses implement Comparable<T>, so compareTo() is already done. A GridLayout(1, 0) of JLabel each having an Icon can be used to display the values. DecRenderer shows how to create icons with a proportional size; you'll want to vary the height over the interval [0, N). GrayIcons & Mad's example show how to animate the display of the icons in some order.

There are a number of reasons why this won't work. Firstly, javax.swing.Timer doesn't work this way. It waits in the background until the given delay has past and then calls the registered ActionListeners actionPerformed method.
Secondly, if it did work this way, it would block the Event Dispatching Thread, preventing it from processing repaint requests.
I think you will find How to use Swing Timers of use.
public class BlinkOut {
public static void main(String[] args) {
new BlinkOut();
}
public BlinkOut() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JLabel[] labels;
private int[] delays;
private Timer timer;
private int index;
public TestPane() {
setLayout(new GridLayout(0, 1));
labels = new JLabel[7];
for (int index = 0; index < 7; index++) {
labels[index] = new JLabel("Label " + (index + 1));
add(labels[index]);
}
delays = new int[] {2000, 3000, 2000, 2000, 2000, 2000, 2000};
JButton hide = new JButton("Hide");
add(hide);
hide.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
System.out.println("Click");
index = 0;
labels[index].setVisible(false);
timer.setDelay(delays[index]);
timer.start();
}
});
timer = new Timer(delays[0], new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
System.out.println("Tick");
timer.stop();
index++;
if (index < 7) {
labels[index].setVisible(false);
timer.setDelay(delays[index]);
timer.start();
}
}
});
timer.setRepeats(false);
timer.setCoalesce(true);
}
}
}

JOptionPane : Display button "Ok" after a certain amount of time

I would like to display the button "OK" of this JOptionPane only after a certain amount of time (let's say for example 5 sec). (My aim is actually to let finish some thread work behind this other thread)
JOptionPane jop2 = new JOptionPane();
jop2.showMessageDialog(null, "Please wait 5s", "WAIT", JOptionPane.INFORMATION_MESSAGE);
I don't know at all how to do that, could you provide me some code working which will answer to this problem?
Thank you very much in advance!

There is no specific way to do this using JOptionPane. You will have to create a custom dialog and reveal the OK button after a fixed time. You could use one pass of a Swing timer.
ActionListener taskPerformer = new ActionListener() {
public void actionPerformed(ActionEvent evt) {
button.setVisible(true);
}
};
Timer timer = new Timer(0, taskPerformer);
timer.setInitialDelay(5000);
timer.setRepeats(false);
timer.start();

It sounds like what you're looking for is a combination of the SwingWorker and the ProgressMonitor. The SwingWorker will preform your long running task (the 5 second one), and inform the user of how it's progressing using the ProgressMonitor. An example showing you how to get the two working together can be found here:
getting the cancel event of Java ProgressMonitor
Of course, if you're convinced you want to take the approach of displaying the continue button once the work is done, here's an example that should get you started in the right direction. You'll use a SwingWorker to alert your Dialog that the long running background task has completed.
import java.awt.*;
import java.awt.Dialog.ModalityType;
import java.awt.event.*;
import javax.swing.*;
public class TempProject extends Box{
public TempProject(){
super(BoxLayout.Y_AXIS);
//Contains the content of the Alert Dialog
Box info = Box.createVerticalBox();
info.add(new Label("Please wait 5 seconds"));
final JButton continueButton = new JButton("Continue");
info.add(continueButton);
//The alert to wait 5 seconds
final JDialog d = new JDialog();
d.setTitle("WAIT");
d.setModalityType(ModalityType.APPLICATION_MODAL);
d.setContentPane(info);
d.pack();
//The action of the "Continue Button"
continueButton.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent arg0) {
d.dispose();
}
});
continueButton.setVisible(false);
//Thread That Does Work
final SwingWorker sw = new SwingWorker<Integer, Integer>()
{
protected Integer doInBackground() throws Exception {
//Do long running thread work here
int i = 0;
while (i++ < 100) {
System.out.println(i);
Thread.sleep(100);
}
return null;
}
#Override
protected void done(){
// What to do when the long runnng thread is done
continueButton.setVisible(true);
}
};
//Button to start the long running task
JButton button = new JButton("Click Me");
button.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent arg0) {
sw.execute();
d.setVisible(true);
}});
add(button);
}
public static void main(String args[])
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
JFrame frame = new JFrame();
frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
frame.setContentPane(new TempProject());
frame.setPreferredSize(new Dimension(500, 400));
frame.pack();
frame.setVisible(true);
}
});
}
}

you could use something like this to stop the code for 5 seconds
try {
Thread.sleep(5000); // do nothing for 5000 miliseconds (5 seconds)
} catch (InterruptedException e) {
e.printStackTrace();
}

Implement StopWatch

Could anyone explain why my start/stop button doesn't work please? This is not a full implemented StopWatch but I got stuck here. Any help is appreciated! This is my first time posting question in forum so if there is any problem in my post, please tell me.
This is my code:
public class StopWatch {
private static boolean tiktok;
public static void setGo(boolean go) {
tiktok = go;
}
public static void main(String[] args) {
int counter = 0;
StopWatch stop = new StopWatch();
ClockFrame window = new ClockFrame("StopWatch");
JLabel lb = window.init();
while (true) {
lb.setText(Integer.toString(counter++));
if (counter == 61) {
counter = 0;
}
try {
Thread.sleep(1000);
} catch (InterruptedException ex) {
}
}
}
}
class ClockFrame extends JFrame {
JLabel hour, minus, sec;
public ClockFrame(String title) {
super(title);
}
JLabel init() {
JFrame frame = new JFrame("Stop Watch");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel time = new JPanel();
hour = new JLabel("0");
minus = new JLabel("0");
sec = new JLabel("0");
time.add(hour);
time.add(minus);
time.add(sec);
JPanel pane = new JPanel();
pane.setLayout(new FlowLayout());
JButton start = new JButton("Start");
start.addActionListener(new startstopActionListener(true));
JButton stop = new JButton("Stop");
stop.addActionListener(new startstopActionListener(false));
JButton reset = new JButton("Reset");
pane.add(start);
pane.add(stop);
pane.add(reset);
Container window = frame.getContentPane();
window.setLayout(new GridLayout(2, 1));
window.add(pane);
window.add(time);
frame.setSize(500, 200);
frame.setVisible(true);
return sec;
}
}
class startstopActionListener implements ActionListener {
private boolean b;
public startstopActionListener(boolean b) {
this.b = b;
}
#Override
public void actionPerformed(ActionEvent e) {
StopWatch.setGo(b);
}
}

You don't respect Swing's threading policy:
Swing components should only be used from the event dispatch thread
Long-running and blocking methods (such as the one with the infinite loop updating the label) should be run out of the event dispatch thread (but the update of the label must be made in the EDT - see rule 1)
Read the Swing tutorial about concurrency.

If you want to make stopwatch in Swing, you best take a look at the javax.swing.Timer class. It makes it very easy to periodically update a Swing component (in your case a JLabel). Using the Timer avoids the Thread.sleep call, which you should never call on the Event Dispatch Thread as it blocks the UI.
JB Nizet already provided a link to Swing concurrency tutorial. I would suggest you also take a look at the links provided in the Swing concurrency section of the 'Swing info page' of this site, and my answer on a related question.

Progress bar to run simultaneously with a function(in another class)

I have created a form on which two components are present, button and progressbar (Netbeans drag and drop).Form contains the main method from where my application starts.I have created another class as well in which i have written a function.What i want is that when i press a button the application goes into the function and the progressbar runs simultaneously with it and when that function is complete with its functionality the the progress bar shows 100% complete.Now this function can take anytime for its completion so i cannot set the max value for the progressbar.So, what to do in this case?Can anyone please provide me with a good example .

JProgressBar.setIndeterminate(true)

Since what sort of a work you are doing inside that so called "Called Function", so it's tough to say, what you want in the scenario, though you can put your lines like progressBar.setValue(someProgress); at regular intervals with it's Indeterminate State to true, and at the end of the function you can simply say that progressBar.setValue(100); and the Indeterminate State will turn to false here, so that it can show that to the end user.
Have a look at this sample program :
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class ProgressExample
{
public static JProgressBar progressBar;
private void createAndDisplayGUI()
{
JFrame frame = new JFrame("Progress Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationByPlatform(true);
JPanel contentPane = new JPanel();
contentPane.setLayout(new BorderLayout(5, 5));
progressBar = new JProgressBar(0, 100);
progressBar.setValue(0);
JButton button = new JButton("START");
button.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
progressBar.setIndeterminate(true);
WorkingDialog wd = new WorkingDialog();
wd.createAndDisplayDialog();
}
});
contentPane.add(progressBar, BorderLayout.PAGE_START);
contentPane.add(button, BorderLayout.PAGE_END);
frame.setContentPane(contentPane);
frame.pack();
frame.setVisible(true);
}
public static void main(String... args)
{
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
new ProgressExample().createAndDisplayGUI();
}
});
}
}
class WorkingDialog extends JDialog
{
private String message = "HelloWorld";
private int count = 0;
private JTextField tfield;
private Timer timer;
private ActionListener timerAction = new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
if (count == 10)
{
timer.stop();
ProgressExample.progressBar.setIndeterminate(false);
ProgressExample.progressBar.setValue(100);
ProgressExample.progressBar.setStringPainted(true);
dispose();
return;
}
tfield.setText(tfield.getText() + message.charAt(count));
count++;
}
};
public void createAndDisplayDialog()
{
setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
setLocationByPlatform(true);
JPanel panel = new JPanel();
tfield = new JTextField(10);
panel.add(tfield);
add(panel);
pack();
setVisible(true);
timer = new Timer(1000, timerAction);
timer.start();
}
}
So , it seems like you are write
ProgressExample.progressBar.setIndeterminate(false);
ProgressExample.progressBar.setValue(100);
ProgressExample.progressBar.setStringPainted(true);
after your while loop.

You can take a look at my answer in a previous SO question, which contains a sample using a JProgressBar which gets updates from another Thread by using a SwingWorker. Whether or not to use a SwingWorker depends a bit on your use case. If the function take some time to run you better use the SwingWorker to avoid blocking the UI.