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Change background colour on typing certain value (jNumberField)

I am trying to change the background colour of a number field based on the numbers that are typed in. Just like a number field turns red when you type a letter in it. I want it to also change red when you type numbers below 1 and above 7.
I understand that you can do this with a button, but I want it to change when you're typing.
This is my code:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
public class applet03 extends JApplet {
private JButton bHoeveelheid = new JButton();
private JNumberField nfAantal = new JNumberField();
private JTextArea taLijst = new JTextArea("");
private JScrollPane taLijstScrollPane = new JScrollPane(taLijst);
public void init() {
Container cp = getContentPane();
cp.setLayout(null);
cp.setBounds(0, 0, 442, 478);
bHoeveelheid.setBounds(224, 56, 59, 33);
bHoeveelheid.setMargin(new Insets(2, 2, 2, 2));
bHoeveelheid.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
bHoeveelheid_ActionPerformed(evt);
}
});
cp.add(bHoeveelheid);
nfAantal.setBounds(304, 56, 99, 36);
nfAantal.setText("Vul getal in");
nfAantal.setHorizontalAlignment(SwingConstants.CENTER);
nfAantal.addFocusListener(new FocusAdapter() {
public void focusGained(FocusEvent evt) {
nfAantal_FocusGained(evt);
}
});
nfAantal.addKeyListener(new KeyAdapter() {
public void keyPressed(KeyEvent evt) {
nfAantal_KeyPressed(evt);
}
});
cp.add(nfAantal);
taLijstScrollPane.setBounds(224, 136, 168, 180);
cp.add(taLijstScrollPane);
}
public void bHoeveelheid_ActionPerformed(ActionEvent evt) {
if (nfAantal.getInt() < 1 || nfAantal.getInt() > 7) {
nfAantal.setBackground(Color.RED);
} else {
//some other code (not impotant for now)
}
}
public void nfAantal_FocusGained(FocusEvent evt) {
if (nfAantal.getText().equals("Vul getal in")) {
nfAantal.clear();
}
}
public void nfAantal_KeyPressed(KeyEvent evt) {
if (nfAantal.getInt() < 1 || nfAantal.getInt() > 7) {
nfAantal.setBackground(Color.RED);
} else {
//some other code (not impotant for now)
}
}
}
The button part works, but the KeyEvent not.
And when I run this I keep getting these errors:
Exception in thread "AWT-EventQueue-1" java.lang.NumberFormatException: empty String
But when I do this, it kinda works. I still get the same errors but it works. (By the way not optimal, because it only appends it to the text field every second key pressing.):
public void nfAantal_KeyPressed(KeyEvent evt) {
if (nfAantal.getInt() < 1 || nfAantal.getInt() > 7) {
taLijst.append(nfAantal.getText());
} else {
//some other code (not impotant for now)
}
}
So if someone knows why this doesn't work or knows a better way to accomplish this. Then that would be very appreciated!
(By the way I use Java 1.8)
Edit:
I now have (nfAantal.getText().length() > 0) && (nfAantal.getInt() < 1 || nfAantal.getInt() > 7) in the if statement and that got rid of the errors. (Thanks to #Joe)
But that still doesn't solve my question on how to turn the background red on certain values.
Aditional information about JNumberField:
I think this link has the code that makes up JNumberField and this link contains a download to the .jar file with in there the JNumberField Java file.
Another edit:
I think I found out for myself why it doesn't work with a JNumberfield; in the code it changes the background to white if its value is numeric so only if there is a way to get around this part of the code or change it (which I don't know how to do) my question can be answered for a JNumberField, if this isn't the case then I will use the JFormattedTextField instead.
This is the code that needs to be altered or circumvented:
protected void processKeyEvent(KeyEvent e) {
super.processKeyEvent(e);
if (isNumeric() || getText().equals("-") ||
getText().equals("") || getText().equals("."))
setBackground(Color.white);
else
setBackground(Color.red);
}

I don't know what a JNumberField is. It's not part of the JDK and when I searched with Google, it turned up several different ones.
I also don't understand why you are writing an applet.
Therefore, the below code may not be appropriate since it is a stand-alone Swing application that uses JFormattedTextField and DocumentListener.
Explanations after the code.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.EventQueue;
import java.text.NumberFormat;
import javax.swing.JFormattedTextField;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;
import javax.swing.text.NumberFormatter;
public class RedNumbr implements DocumentListener, Runnable {
private JFormattedTextField aantal;
private JFrame frame;
#Override
public void insertUpdate(DocumentEvent event) {
handleDocumentEvent(event);
}
#Override
public void removeUpdate(DocumentEvent event) {
handleDocumentEvent(event);
}
#Override
public void changedUpdate(DocumentEvent event) {
// Never called for 'JFormattedTextField'
}
#Override
public void run() {
showGui();
}
private JPanel createNumberPanel() {
JPanel numberPanel = new JPanel();
NumberFormat format = NumberFormat.getIntegerInstance();
NumberFormatter formatter = new NumberFormatter(format);
aantal = new JFormattedTextField(formatter);
aantal.setColumns(10);
Document doc = aantal.getDocument();
doc.addDocumentListener(this);
numberPanel.add(aantal);
return numberPanel;
}
private void handleDocumentEvent(DocumentEvent event) {
Document doc = event.getDocument();
int len = doc.getLength();
if (len > 0) {
try {
String text = doc.getText(0, len);
int number = Integer.parseInt(text);
Color fg;
if (number < 1 || number > 7) {
fg = Color.red;
}
else {
fg = UIManager.getColor("TextField.foreground");
}
aantal.setForeground(fg);
}
catch (BadLocationException | NumberFormatException x) {
// Ignore.
}
}
}
private void showGui() {
frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(createNumberPanel(), BorderLayout.CENTER);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new RedNumbr());
}
}
Whenever the contents of the JFormattedTextField are changed, the relevant DocumentListener method is invoked. In those methods I check whether the JFormattedTextField contains a number and if it does then I change the foreground color of the JFormattedTextField according to your conditions, i.e. if the number is less than one (1) or greater than 7 (seven).
Note that the NumberFormatter does not prevent entering non-digits because JFormattedTextField handles that when it loses focus. Nonetheless it handles entering positive and negative numbers, which saves you some work. And the point of my answer is simply to demonstrate how to change the foreground color based on the entered text, which I believe answers your question.
EDIT
In order to change the background of the JFormattedTextField, rather than the foreground, you just need to change two lines in my code, above.
Replace
fg = UIManager.getColor("TextField.foreground");
with
fg = UIManager.getColor("TextField.background");
and also replace
aantal.setForeground(fg);
with
aantal.setBackground(fg);

I suppose that the JNumberField is an extension of JTextField and if it is the case it could be the synchronization problem between the main thread and the thread that is triggered by the KeyEvent action. To make sure that the event thread will be carried out you code it with invokeLater.
public void nfAantal_KeyPressed(KeyEvent evt) {
if (nfAantal.getText().length() > 0) && (nfAantal.getInt() < 1 || nfAantal.getInt() > 7) {
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
nfAantal.setBackground(Color.RED);
}
});
} else {
//some other code (not impotant for now)
}
}

JAVA - JFrame not looking proper when called from action listener

I have a problem with one of my frames not looking as it should, when it is called upon the press of a button.
The frame looks as if it was rendered improperly, the label text in it is shortened, however when i move the same line of code outside the action listener, it works as it should.
I have a sort of main menu, with two buttons, only the Generate Menu works at the moment, it looks like this:
https://i.imgur.com/k1Ne5v9.png
The code for the action listener:
runMenuButt.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
System.out.println("Generate Menu pressed");
mF.dispose();
MenuGenerator.generateTheMenu();
}
});
The result looks wrong: https://i.imgur.com/n86y4CD.png
The frame is also unresponsive, clikcing X does not, while it should close the frame and the application.
However changing the code to:
runMenuButt.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
System.out.println("Generate Menu pressed");
//mF.dispose();
}
});
MenuGenerator.generateTheMenu();
Produces correct look: https://i.imgur.com/TFbkmAO.png
The code for the "Main menu"
public static void openMainMenu() {
Font menuFont = new Font("Courier",Font.BOLD,16);
Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
mF.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mF.setSize(465,230);
mF.setLocation(dim.width/2-mF.getSize().width/2, dim.height/2-mF.getSize().height/2);
mF.getContentPane().setBackground(Color.WHITE);
Color blueSteel = new Color(70,107,176);
JPanel p = new JPanel();
p.setSize(600,50);
p.setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
p.setLocation((mF.getWidth() - p.getWidth()) /2, 20);
p.setBackground(blueSteel);
JLabel l = new JLabel("Welcome to the menu GENERATORRRR");
l.setFont(menuFont);
l.setForeground(Color.WHITE);
p.add(l, gbc);
JButton runMenuButt = new JButton("Generate Menu");
runMenuButt.setLocation(20 , 90);
JButton manageRecipButt = new JButton("Manage Recipients");
manageRecipButt.setLocation(240 , 90);
menuUtilities.formatButton(runMenuButt);
menuUtilities.formatButton(manageRecipButt);
mF.setResizable(false);
mF.setLayout(null);
mF.add(runMenuButt);
mF.add(manageRecipButt);
mF.add(p);
mF.setVisible(true);
runMenuButt.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
System.out.println("Generate Menu pressed");
//mF.dispose();
}
});
MenuGenerator.generateTheMenu();
manageRecipButt.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
JOptionPane.showMessageDialog(null, "Not supported yet", "Function not yet available",JOptionPane.INFORMATION_MESSAGE);
}
});
//System.out.println(mF.getContentPane().getSize());
}
And the status bar:
public class StatusBar {
private static JLabel statusLabel= new JLabel("Starting");
private static JFrame statusFrame = new JFrame("Generation Status");
public static void createStatusBar() {
Font menuFont = new Font(Font.MONOSPACED,Font.BOLD,20);
Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
statusFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
statusFrame.setSize(700,100);
JPanel p = new JPanel();
p.setPreferredSize(new Dimension(100,100));
statusLabel.setFont(menuFont);
p.add(statusLabel);
statusFrame.add(p,BorderLayout.CENTER);
statusFrame.setLocation(dim.width/2-statusFrame.getSize().width/2, dim.height/2-statusFrame.getSize().height/2);
statusFrame.setVisible(true);
}
public static void setStatusBar(String statusText) {
statusLabel.setText(statusText);
statusLabel.paintImmediately(statusLabel.getVisibleRect());
statusLabel.revalidate();
}
public static void closeStatusBar(){
statusFrame.dispose();
}
}
I create the bar with this line:
StatusBar.createStatusBar();
Why does the status bar not render properly when the MenuGenerator.generateTheMenu(); is called from the action listener?
Here is minimal code that reproduces this behavior for anyone who would like to test it: It also uses class for the StatusBar, which is already posted.
public class MinimalClass {
private static JFrame mF = new JFrame("Main Menu");
public static void main(String[] args) {
openMainMenu();
}
public static void openMainMenu() {
Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
mF.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mF.setSize(465,230);
mF.setLocation(dim.width/2-mF.getSize().width/2, dim.height/2-mF.getSize().height/2);
mF.getContentPane().setBackground(Color.WHITE);
JButton runMenuButt = new JButton("Generate Menu");
runMenuButt.setLocation(20 , 90);
runMenuButt.setSize(200 , 85);
mF.setResizable(false);
mF.setLayout(null);
mF.add(runMenuButt);
mF.setVisible(true);
runMenuButt.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
System.out.println("Generate Menu pressed");
mF.dispose();
generateTheMenu();
}
});
}
public static void generateTheMenu() {
System.setProperty("sun.java2d.cmm", "sun.java2d.cmm.kcms.KcmsServiceProvider");
String rawMenuOutput = "";
try {
rawMenuOutput= getMenuInJavaNow();
} catch (Exception e){
System.out.println("Something went terribly wrong");
}
System.out.println(rawMenuOutput);
}
public static String getMenuInJavaNow() throws IOException {
String rawMenuOutput = "Restaurant Menu" ;
rawMenuOutput = rawMenuOutput + "Test line";
String []menuOtpArr = new String [3];
try {
StatusBar.createStatusBar();
TimeUnit.SECONDS.sleep(2);
StatusBar.setStatusBar("Test1");
TimeUnit.SECONDS.sleep(2);
menuOtpArr[0]="Test line";
StatusBar.setStatusBar("Test2");
TimeUnit.SECONDS.sleep(2);
menuOtpArr[1]="Test line";
StatusBar.setStatusBar("Test3");
TimeUnit.SECONDS.sleep(2);
menuOtpArr[2]="Test line";
StatusBar.setStatusBar("Test4");
TimeUnit.SECONDS.sleep(2);
StatusBar.closeStatusBar();
} catch (Exception e) {
}
for (int i=0;i < menuOtpArr.length;i++) {
rawMenuOutput = rawMenuOutput + "\n\n" +menuOtpArr[i];
}
return rawMenuOutput;
}
}
Thank you for your time

statusLabel.paintImmediately(statusLabel.getVisibleRect()); seems to masking a larger issue.
The problem is, Swing is single threaded (and NOT thread safe). This means that when you call TimeUnit.SECONDS.sleep(2); from within getMenuInJavaNow, which is called by generateTheMenu, which is called by the ActionListener, it's been called within the context of the Event Dispatching Thread.
This is putting the EDT to sleep, meaning that it isn't processing layout or paint requests (properly)
Start by having a read of Concurrency in Swing for more details
Now, you have a larger issue, how to solve it. For the answer to that question, we require a lot more context then is currently available.
The getMenuInJavaNow seems to be returning some values, to what end I'm not sure.
"A" solution, would be to use a SwingWorker (see Worker Threads and SwingWorker for more details). It provides the ability to execute long running tasks in the background, but also provides the means for sync updates back to the UI, for example...
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.Insets;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.List;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingWorker;
public class MinimalClass {
private static JFrame mF = new JFrame("Main Menu");
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
openMainMenu();
}
});
}
public static void openMainMenu() {
Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
mF.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mF.setLocationRelativeTo(null);
mF.getContentPane().setBackground(Color.WHITE);
JButton runMenuButt = new JButton("Generate Menu");
runMenuButt.setMargin(new Insets(25, 25, 25, 25));
JPanel buttons = new JPanel(new GridLayout(0, 2));
buttons.add(runMenuButt);
mF.add(buttons);
mF.pack();
mF.setVisible(true);
runMenuButt.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
System.out.println("Generate Menu pressed");
mF.dispose();
generateTheMenu();
}
});
}
public static void generateTheMenu() {
System.setProperty("sun.java2d.cmm", "sun.java2d.cmm.kcms.KcmsServiceProvider");
StatusBar.createStatusBar();
SwingWorker<String, String> worker = new SwingWorker<String, String>() {
#Override
protected String doInBackground() throws Exception {
String rawMenuOutput = "Restaurant Menu";
rawMenuOutput = rawMenuOutput + "Test line";
String[] menuOtpArr = new String[3];
try {
TimeUnit.SECONDS.sleep(2);
publish("1234567890123456789012345678901234567890");
TimeUnit.SECONDS.sleep(2);
publish("This is a test");
TimeUnit.SECONDS.sleep(2);
publish("More testing");
TimeUnit.SECONDS.sleep(2);
publish("Still testing");
TimeUnit.SECONDS.sleep(2);
} catch (Exception e) {
}
for (int i = 0; i < menuOtpArr.length; i++) {
rawMenuOutput = rawMenuOutput + "\n\n" + menuOtpArr[i];
}
return rawMenuOutput;
}
#Override
protected void done() {
StatusBar.closeStatusBar();
}
#Override
protected void process(List<String> chunks) {
StatusBar.setStatusBar(chunks.get(chunks.size() - 1));
}
};
worker.addPropertyChangeListener(new PropertyChangeListener() {
#Override
public void propertyChange(PropertyChangeEvent evt) {
if (worker.getState() == SwingWorker.StateValue.DONE) {
try {
String result = worker.get();
System.out.println(result);
StatusBar.closeStatusBar();
} catch (InterruptedException | ExecutionException ex) {
ex.printStackTrace();
}
}
}
});
worker.execute();
}
public static class StatusBar {
private static JLabel statusLabel = new JLabel("Starting");
private static JFrame statusFrame = new JFrame("Generation Status");
public static void createStatusBar() {
Font menuFont = new Font(Font.MONOSPACED, Font.BOLD, 20);
Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
statusFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
statusFrame.setSize(700, 100);
JPanel p = new JPanel();
p.setBackground(Color.RED);
// p.setPreferredSize(new Dimension(100, 100));
statusLabel.setFont(menuFont);
p.add(statusLabel);
statusFrame.add(p, BorderLayout.CENTER);
statusFrame.setLocationRelativeTo(null);
statusFrame.setVisible(true);
}
public static void setStatusBar(String statusText) {
statusLabel.setText(statusText);
}
public static void closeStatusBar() {
statusFrame.dispose();
}
}
}
Observations...
static is not your friend, especially in cases like this. You really, really, really need to learn to live without it.
setLayout(null) is not doing you any favours, especially in the long run. Take the time to go through Laying Out Components Within a Container and start making proper use of layout managers, they might seem "complicated", but they will save you from a lot of hair loss
Avoid using setPreferred/Minimum/MaximumSize where ever possible, you are robing the component of the ability to provide useful rendering hints which may change across platforms and rendering pipelines
Just a quick follow up question, what is the difference between done and addPropertyListener ? Is there any? Isnt it redundant to use both?
The example here is pretty basic, for me I've used done to handle what the SwingWorker "knows" needs to be done, it doesn't however, know what is to be done with the result.
I've used the PropertyChangeListener to deal with that instead - the point - it's an example.
And I also noticed, that I dont need to actually publish, as calling StatusBar.setStatusBar(""); works as well. Is it necessary to use publish?
In a word YES. Swing is NOT thread safe, calling StatusBar.setStatusBar("") directly can lead to some weird and unexpected results. publish pushes the call into the Event Dispatching Thread, making it safe to update the UI from within.
I have the code for generating the String I want to set as the StatusBar Title in another class, not in the generateTheMenu, therefore it is more convenient for me to simply call .setStatusBar. The not minimal code I have is actually something like this
This is where things like interfaces come in really handy. You "string" generating class "could" either return the resulting text OR you could pass a reference to a interface implementation which is used to "display" it. This way, your SwingWorker could act as a consumer for the String and pass it through the publish method.
There are a number of really important concepts to understand.
You want to decouple your code. This makes it easier to change certain parts of the code without affecting the other parts
You want to be able to "code to interface, not implementation". This goes hand in hand with the first comment. Basically, you want to "hide" the implementation details as much as possible - lots of different reasons for it, but it helps keep your code lean, helps make the follow more understandable and stops one part of the code from accessing another it really has no responsibility to do so (is the string generation really responsible for updating the status bar? IMHO - not really)
There is also a swagger of design patterns available to make solving issues easier. I've already mentioned the concept of "produce/consumer", but this is just one
The "Event Dispatching Thread"
The Event Dispatch Thread
Java Event-Dispatching Thread explanation
Swing threading and the event-dispatch thread

Java - Why does my print statement not run

So this is my code:
System.out.println("System Exiting...");
long current = System.currentTimeMillis();
long disired = current + 4000;
boolean done = false;
while (!done)
{
current = System.currentTimeMillis();
if (current == disired)
{
done = true;
System.exit(0);
}
}
My problem is that the print statement doesn't run, well it does run, but it runs at the same time as the exit statement, so you don't see it
[EDIT] Ok, so i just ran this code in its own file(with nothing else), and it works as i want, it prints "system Exiting..." it waits 4 seconds, and the code exits.
so it has to be something to do with the fact that i have this code inside an event listener

Your if condition is much too restrictive since your code will almost never get the times to be exactly equal, but the change needed is very simple:
Change
// hitting this exactly is like finding the proverbial needle
// in the haystack -- almost impossible to do.
if (current == disired)
to
// this is guaranteed to work.
// note if this is in English, you'll want to change disired to desired
if (current >= disired)
Having said this, your while (true) loop is not a good thing to do as it will needlessly tie up the CPU with empty cycles. Instead use some type of event notification or call-back system like ChangeListener or a PropertyChangeListener or a Timer.
You state:
yes it is within a swing GUI
You're calling a long while (true) block of code on the Swing event thread, rendering this thread ineffective. Since the event thread is responsible for all Swing graphics and user interactions, this effectively freezes your GUI until the while loop completes. The solution is obvious: 1) use a Swing Timer for your delay, not a while true loop (this is the callback mechanism that I mentioned in my original answer), and 2) in the future, please give us this important relevant information with the original question since it changes the entire nature of the question.
e.g.
// caveat: code not tested
System.out.println("System Exiting...");
int delay = 4 * 1000;
new Timer(delay, new ActionListener(){
#Override
public void actionPerformed(ActionEvent e) {
System.out. println("Exited");
System.exit(0);
}
}).start();
e.g.,
import java.awt.Component;
import java.awt.Window;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import javax.swing.*;
#SuppressWarnings("serial")
public class TestDelayedExit extends JPanel {
private static final int GAP = 100;
public TestDelayedExit() {
add(new JButton(new DisposeAction("Exit", KeyEvent.VK_X)));
setBorder(BorderFactory.createEmptyBorder(GAP, GAP, GAP, GAP));
}
private static void createAndShowGui() {
JFrame frame = new JFrame("TestDelayedExit");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new TestDelayedExit());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
private class DisposeAction extends AbstractAction {
private int count = 4;
private Timer timer;
public DisposeAction(String name, int mnemonic) {
super(name);
putValue(MNEMONIC_KEY, mnemonic); // for alt-key combo
}
#Override
public void actionPerformed(ActionEvent e) {
if (timer != null && timer.isRunning()) {
return;
}
final Component c = (Component) e.getSource();
int timerDelay = 1000;
putValue(NAME, String.valueOf(count));
timer = new Timer(timerDelay, new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (count == 0) {
((Timer) e.getSource()).stop();
// this will not work for JMenuItems, and for that
// you would need to get the pop up window's parent component
Window win = SwingUtilities.getWindowAncestor(c);
if (win != null) {
win.dispose();
}
} else {
count--;
putValue(NAME, String.valueOf(count));
}
}
});
timer.start();
}
}
}

JDialog loses opacity after deiconify

Creating a transparent and undercoated JDialog with a JFrame as its parent
will lose transparency upon an iconify/deiconify sequence.
Example:
final JFrame f = new JFrame();
f.setSize(200, 200);
final JDialog d = new JDialog(f, false);
d.setSize(200, 200);
d.setUndecorated(true);
d.setOpacity(.8f);
f.setLocationRelativeTo(null);
d.setLocation(f.getLocation().x + 210, f.getLocation().y);
f.setVisible(true);
d.setVisible(true);
Before iconify, the JDialog is created fine. Here is a screenshot.
After an iconify/deiconify sequence, the JDialog is 100% opaque.
I'm looking for solution to this problem and thinking I'm doing something
incorrect or missing some code.
My environment is Java(TM) SE Runtime Environment (build 1.8.0_11-b12)
running on Microsoft Windows [Version 6.1.7601].
2014-11-13: There is an open JDK bug for this problem
JDK-8062946 Transparent JDialog will lose transparency upon iconify/deiconify sequence.
https://bugs.openjdk.java.net/browse/JDK-8062946

Seems like a bit of a bug to me.
The following seems to work using JDK7 on Windows 7:
f.addWindowListener( new WindowAdapter()
{
#Override
public void windowDeiconified(WindowEvent e)
{
d.setVisible(false);
d.setVisible(true);
}
});

Try the following. I've had various problems with the undecorated JDialog and when I find a
bypass to a new symptom I add it to this method. This is a trimmed example. Add error checking, exception handling and modify as necessary to suit your needs ( ie add listener removal code if your app creates and destroys passed parentWindow objects).
package trimmed.stackoverflow.example;
import java.awt.Color;
import java.awt.Window;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
import javax.swing.JDialog;
import javax.swing.SwingUtilities;
public class Helper_Swing {
private static Helper_Swing instance;
private Helper_Swing() {
instance = this;
}
public static Helper_Swing getInstance() {
return instance == null ? new Helper_Swing() : instance;
}
private static class J42WindowAdapter extends WindowAdapter {
final private Window window;
final private JDialog dialog;
private Color colorBG = null;
private float opacity = 0.0f;
private J42WindowAdapter(final Window window, final JDialog dialog) {
super();
this.window = window;
this.dialog = dialog;
this.colorBG = window.getBackground();
this.opacity = window.getOpacity();
}
#Override
public void windowIconified(final WindowEvent e) {
colorBG = dialog.getBackground();
opacity = dialog.getOpacity();
dialog.setOpacity(1.0f); // Must call 1st
dialog.setBackground(Color.BLACK); // Must call 2nd
}
#Override
public void windowDeiconified(final WindowEvent e) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
dialog.setBackground(colorBG);
dialog.setOpacity(opacity);
dialog.setVisible(true);
dialog.repaint();
}
});
}
}
public void bugFix_transparentJDialog(final Window parentWindow, JDialog childWindow) {
if (parentWindow != null && childWindow != null && childWindow.isUndecorated()) {
final WindowListener[] listeners = parentWindow.getWindowListeners();
for (int x = 0; x != listeners.length; x++) {
if (listeners[x] instanceof J42WindowAdapter) {
final J42WindowAdapter adapter = (J42WindowAdapter) listeners[x];
if (adapter.window == parentWindow && adapter.dialog == childWindow) {
childWindow = null;
break;
}
}
}
if (childWindow != null) {
parentWindow.addWindowListener(new J42WindowAdapter(parentWindow, childWindow));
}
}
}
}
Usage example:
Helper_Swing.getInstance().bugFix_transparentJDialog(parentWindow, dialog);

In Java how do you trap the event before the new JTab is switched to?

how do you trap the event before the new tab is switched to?
In every Tab I have JTable and i do something with it's data(delete, add , update). I would like to do data validation(save or cancel changes) before switching to the new tab. I use Java 1.5.
class ViewPanel extends JPanel
{
private void Components() {
setPreferredSize(new Dimension(700, 400));
tabbedPane.addTab("DC", ANSFER.getIcon(),new DcTabPanel(this), "DC");
tabbedPane.addTab("PC", THUMB4.getIcon(),new PcTabPanel(this), "PC");
tabbedPane.addChangeListener(this);
add(tabbedPane);
}
public void stateChanged(ChangeEvent e) {
}
}

JTabbedPane is backed by a SingleSelectionModel. If you extend DefaultSingleSelectionModel, you can override the setSelectedIndex method and implement your logic.
// in new selection model:
public void setSelectedIndex(int index) {
// do pre-switch things here
super.setSelectedIndex(index);
}
// in ViewPanel, on tabbedPane create:
tabbedPane.setModel(newSelectionModel);
The reason you can't simply use a ChangeListener is because that fires on change. By extending the selection model, you fire before the tab change.

You can prevent tab switching by extending JTabbedPane and override setSelectedIndex(int). Here is a small example illustrating that. It simply prevents from switching between non-contiguous tabs:
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JTabbedPane;
import javax.swing.SwingUtilities;
public class Test2 {
private static class BlockingTabbedPane extends JTabbedPane {
public static interface TabSwitchAllower {
public boolean allowTabSwitch(int from, int to);
}
private TabSwitchAllower allower;
public BlockingTabbedPane(TabSwitchAllower allower) {
super();
this.allower = allower;
}
#Override
public void setSelectedIndex(int index) {
if (allower == null || allower.allowTabSwitch(getSelectedIndex(), index)) {
super.setSelectedIndex(index);
}
}
}
protected static void initUI() {
final JFrame frame = new JFrame("test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
BlockingTabbedPane.TabSwitchAllower allower = new BlockingTabbedPane.TabSwitchAllower() {
#Override
public boolean allowTabSwitch(int from, int to) {
if (Math.abs(from - to) == 1) {
return true;
} else {
JOptionPane.showMessageDialog(frame, "You can only switch between contiguous tabs");
}
return false;
}
};
JTabbedPane tabbedPane = new BlockingTabbedPane(allower);
for (int i = 0; i < 10; i++) {
tabbedPane.addTab("Tab-" + i, new JLabel("Hello tab " + i));
}
frame.add(tabbedPane);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
initUI();
}
});
}
}

java actionlistener on a tab
How to Write a Change Listener (Oracle Docs)
JTabbedPane API (Oracle Docs)
Those two links should help you out. I haven't really worked with tabbedPanes, but I am assuming that the getSelectedComponent() will return the current selected tab. So you can have a handle to the currentTab which will be set during instantiation. Then you can have something like this.
class TabListener implements ChangeListener {
public void stateChanged(ChangeEvent e) {
// Replace JSlider with whatever your tab's data type is
JSlider source = (JSlider)e.getSource();
// Use the 'currentTab' handle to do what you want.
currentTab = getSelectedComponent();
// I'm assuming that the 'selected component' by the time this stuff
// runs is going to be the new selected tab.
}
}
I am not too confident about my answer, but I certainly hope that this will point you towards the right direction! Please say if you need any clarification or anything! If I happen to discover anything that I think might be useful, I'll be certain to edit my answer!