Develop Reference

Gui program stops after main method executes even if thread is non-daemon

I am a beginner in Java and I appreciate any tips. I was making a simple program that opens a very simple login window and when you enter the correct password (Hello.123), it is supposed to execute a second class that opens another window with a square that can be moved with the arrow keys. I tried executing the second class independently and it worked fine, but when I tried executing it as a part of the main program, it didn´t work. I thought that it was because the second class was executing as a Daemon Thread, so I tried making it a subclass of another class that sets the thread to non-daemon, but that didn´t work either. Is there something I am missing or did I do something wrong? (The code here has the thing to make it non-daemon)
Login.java
package main;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JButton;
import javax.swing.JTextField;
import java.awt.Color;
import java.awt.Font;
import javax.swing.BorderFactory;
import javax.swing.border.Border;
import javax.swing.ImageIcon;
import javax.swing.SwingUtilities;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.event.WindowEvent;
import java.io.IOException;
import java.net.URL;
import main.PostFrameThr.PostFrame;
import main.PostFrameThr;
public class Login {
public static void main(String[] args) throws IOException {
System.out.println("Initializing main Method");
Border border = BorderFactory.createLineBorder(Color.black,5);
JFrame login = new JFrame();
login.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
login.setTitle("Login");
login.setResizable(false);
login.setSize(600, 500);
login.setLocation(350, 100);
login.setVisible(true);
URL url1 = Login.class.getResource("/resources/WindowLogo.png");
URL url2 = Login.class.getResource("/resources/LoginLogo.png");
ImageIcon logo = new ImageIcon(url1);
ImageIcon loginico = new ImageIcon(url2);
login.setIconImage(logo.getImage());
login.getContentPane().setBackground(Color.gray);
JButton loginButton = new JButton("Login");
loginButton.setBounds(255, 210, 70, 60);
login.add(loginButton);
JTextField password = new JTextField();
password.setBounds(190, 180, 200, 20);
login.add(password);
JLabel logintxt = new JLabel();
logintxt.setText("Please Enter Your Password");
logintxt.setIcon(loginico);
logintxt.setForeground(Color.BLACK);
logintxt.setSize(10, 10);
logintxt.setHorizontalTextPosition(JLabel.CENTER);
logintxt.setVerticalTextPosition(JLabel.TOP);
logintxt.setFont(new Font("Plain",Font.PLAIN,20));
logintxt.setBackground(Color.gray);
logintxt.setOpaque(true);
logintxt.setBorder(border);
logintxt.setVerticalAlignment(JLabel.TOP);
logintxt.setHorizontalAlignment(JLabel.CENTER);
login.add(logintxt);
SwingUtilities.updateComponentTreeUI(login);
int lock = 1;
if(lock==1) {
System.out.println("Finished Loading Login Window Components");
System.out.println("Initializing Login Method");
}
while(lock==1) {
lock = lock + 1;
lock = lock - 1;
String passwordtext = password.getText();
loginButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if(passwordtext.equals("Hello.123")) {
System.out.println("Login Successfull!");
// try {
//Runtime.getRuntime().exec("calc.exe");
//} catch (IOException e1) {
// TODO Auto-generated catch block
//e1.printStackTrace();
//}
new PostFrameThr();
new PostFrame();
login.dispatchEvent(new WindowEvent(login, WindowEvent.WINDOW_CLOSING));
}
}
});
}
}
}
PostFrame.java
package main;
import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.*;
import java.lang.Thread;
class PostFrameThr extends Thread {
static void thr() {
PostFrameThr Thread = new PostFrameThr();
Thread.setDaemon(false);
Thread.start();
new PostFrame();
}
#SuppressWarnings("serial")
public static class PostFrame extends JFrame implements KeyListener {
int X = 155;
int Y = 130;
int size = 70;
JLabel label;
PostFrame(){
this.setTitle("Snake");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setResizable(false);
this.setSize(400, 400);
this.setLayout(null);
this.addKeyListener(this);
this.setLocationRelativeTo(null);
label = new JLabel();
label.setBounds(X, Y, size, size);
label.setBackground(Color.black);
label.setOpaque(true);
label.setVisible(true);
this.add(label);
this.setVisible(true);
SwingUtilities.updateComponentTreeUI(this);
}
#Override
public void keyPressed(KeyEvent e) {
// TODO Auto-generated method stub
switch(e.getKeyChar()) {
case 'w' : label.setLocation(label.getX(), label.getY()-5);
break;
case 'a' : label.setLocation(label.getX()-5, label.getY());
break;
case 's' : label.setLocation(label.getX(), label.getY()+5);
break;
case 'd' : label.setLocation(label.getX()+5, label.getY());
}
}
#Override
public void keyTyped(KeyEvent e) {
// TODO Auto-generated method stub
}
#Override
public void keyReleased(KeyEvent e) {
// TODO Auto-generated method stub
}
}
}

Swing, like most GUI frameworks, is event driven.
Doing something like...
while (lock == 1) {
lock = lock + 1;
lock = lock - 1;
String passwordtext = password.getText();
is not only incorrect, it's also CPU intensive (not to mention that on each iteration, you're adding a new ActionListener to the button)
Instead, just get rid of the loop and when the ActionListener is triggered, get the value from the JTextField
loginButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
String passwordtext = password.getText();
if (passwordtext.equals("Hello.123")) {
System.out.println("Login Successfull!");
new PostFrameThr();
new PostFrame();
login.dispose();
}
}
});
You'll probably want to take the time to look at:
Laying Out Components Within a Container (you're UI broke on my system)
Creating a GUI With Swing
How to Write an Action Listener
Oh, and SwingUtilities.updateComponentTreeUI(login); isn't doing what you think it is doing. Instead, move login.setVisible(true); to the end of the main method

JFrame doesn't appear unless method invoked in main

I have a class which create a JFrame with an image but everytime I create the class and run the method to instantiate it, it doesn't appear. However, I have noticed that if I was to create the exact same class and run the same method in the main then the frame appears.
This is most of the code from the class with the JFrame that I am trying to create:
JFrame myFrame= new JFrame();
public void CreateFrame()
{
JLabel background=new JLabel(new ImageIcon("image.jpg"));
myFrame.add(background);
background.setLayout(new FlowLayout());
myFrame.setLayout(new GridLayout(1,1));
myFrame.setSize(360,250);
myFrame.setUndecorated(true);
myFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
myFrame.setLocation((dim.width/2-170), dim.height/2-125);
myFrame.pack();
myFrame.setVisible(true);
}
If I run the code
MyClass mc = new MyClass();
mc.CreateFrame();
in a method in another class it doesn't come up. However, if I run the exact same code in a main method, it works.
For example, this doesn't work:
Example 1
public class otherClass extends JFrame
{
public void MethodA()
{
MyClass mc = new MyClass();
mc.CreateFrame();
}
public static void main(String[] args)
{
otherClass oc = new otherClass();
oc.MethodA();
}
}
but this does work
Example 2
public class otherClass extends JFrame
{
public void MethodA()
{
//CODE
}
public static void main(String[] args)
{
otherClass oc = new otherClass();
oc.MethodA();
MyClass mc = new MyClass();
mc.CreateFrame();
}
}
Can anyone see where I'm going wrong? Sorry if a stupid mistake, I'm still getting to grips with Java.
Thanks
EDIT
import javax.swing.ImageIcon;
import javax.swing.JWindow;
import javax.swing.JLabel;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.io.*;
import javax.imageio.ImageIO;
import java.util.Timer;
import java.util.Date;
import javax.swing.JFrame;
public class MyClass
{
JFrame homeFrame = new JFrame();
public void createFrame()
{
JLabel background=new JLabel(new ImageIcon("images.jpg"));
myFrame.add(background);
background.setLayout(new FlowLayout());
myFrame.setLayout(new GridLayout(1,1));
myFrame.setSize(360,250);
myFrame.setUndecorated(true);
myFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
myFrame.setLocation((dim.width/2-170), dim.height/2-125);
myFrame.setAlwaysOnTop(true);
myFrame.pack();
myFrame.setVisible(true);
durationOfTime();
}
public void durationOfTime()
{
MainProgram mp = new MainProgram();
long startTime = System.currentTimeMillis();
long elapsedTime = 0L;
int count =0;
while (elapsedTime < 2*1000)
{
if(count==0)
{
mp.launchInitiation();
}
count+=1;
elapsedTime = (new Date()).getTime() - startTime;
}
myFrame.setVisible(false);
mp.homeFrame.setVisible(true);
}
public static void main(String[] args)
{
MyClass mc = new MyClass();
mc.createFrame();
}
}
Full code from class with JFrame trying to make. I am trying to use this JFrame as a splash screen but whatever class I call
MyClass mc = new MyClass();
mc.createFrame();
from, it just doesn't appear. Two seconds do pass by before my main GUI appears up but this method is supposed to be called in a login type frame. However, I have tested it with a blank JFrame / GUI to appear upon button click also and it still doesn't appear.
EDIT2
I also previously tried this SplashScreen example by # http://examples.oreilly.com/jswing2/code/ch08/SplashScreen.java but I couldn't get it to work (same problem, appears when called from main but not when called from action listener)
import java.awt.*;
import javax.swing.*;
public class SplashScreen extends JWindow {
private int duration;
public SplashScreen(int d) {
duration = d;
}
// A simple little method to show a title screen in the center
// of the screen for the amount of time given in the constructor
public void showSplash() {
JPanel content = (JPanel)getContentPane();
content.setBackground(Color.white);
// Set the window's bounds, centering the window
int width = 450;
int height =115;
Dimension screen = Toolkit.getDefaultToolkit().getScreenSize();
int x = (screen.width-width)/2;
int y = (screen.height-height)/2;
setBounds(x,y,width,height);
// Build the splash screen
JLabel label = new JLabel(new ImageIcon("oreilly.gif"));
JLabel copyrt = new JLabel
("Copyright 2002, O'Reilly & Associates", JLabel.CENTER);
copyrt.setFont(new Font("Sans-Serif", Font.BOLD, 12));
content.add(label, BorderLayout.CENTER);
content.add(copyrt, BorderLayout.SOUTH);
Color oraRed = new Color(156, 20, 20, 255);
content.setBorder(BorderFactory.createLineBorder(oraRed, 10));
// Display it
setVisible(true);
// Wait a little while, maybe while loading resources
ClassToLoad ctl = new ClassToLoad();
try {
Thread.sleep(duration);
ctl.initiate();
} catch (Exception e) {}
setVisible(false);
}
public void showSplashAndExit() {
showSplash();
System.exit(0);
}
public static void main(String[] args) {
// Throw a nice little title page up on the screen first
SplashScreen splash = new SplashScreen(10000);
// Normally, we'd call splash.showSplash() and get on with the program.
// But, since this is only a test...
splash.showSplashAndExit();
}
}
I added the code in the lines with ClassToLoad and this SplashScreen is called on an action listener, what happens is the program waits the 2 seconds that I tell it to, no frame appears, and then the main class that I wanted to load while the splash screen is visible loads. I tried this method first but this didn't work which lead to me using the code listed above this edit
EDIT 3
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class TestFrame extends JFrame implements ActionListener
{
JPanel thePanel = new JPanel(null); //layout
JButton button = new JButton();
public void startGUI()
{
this.setLayout(new GridLayout(1,1));
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
CREATEMYPANEL();
this.add(thePanel);
this.setTitle("NO_TITLE_SET");
this.setSize(400,400);
this.setVisible(true);
this.setResizable(true);
}
public void CREATEMYPANEL()
{
button.setLocation(242,151);
button.setSize(100,50);
button.addActionListener(this);
button.setText("button");
thePanel.add(button);
}
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==button)
{
System.out.println("button has been pressed ");
SplashScreen splash = new SplashScreen(1000);
splash.showSplash();
}
}
public static void main(String[] args )
{
TestFrame tf = new TestFrame();
tf.startGUI();
}
}
An example of where I call splash screen from. Still doesn't work. Also, just a note that the image I am loading is a local image
Apologies for bad question formatting

Your code works for me except for some details I noticed:
You're calling setSize(...) and then calling pack(). Probably your image isn't being loaded and thus your JFrame has a size of 0, 0. (And thus it looks like it never appears). .pack() and .setSize(...) are mutually exclusive.
You're setting the JLabel's layout manager to FlowLayout but never adding anything to it. (You can safely remove it)
I see you're importing java.util.Timer if you want to dispose the JFrame after 2 seconds, then you should be using a javax.swing.Timer instead. Otherwise you could get problems related to threading.
Also don't forget to place your program on the Event Dispatch Thread (EDT) as Swing is not thread safe
Following above recommendations you can have this code:
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.net.MalformedURLException;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class SplashscreenSample {
private JFrame myFrame;
private JLabel background;
private Timer timer;
public void createFrame() {
timer = new Timer(2000, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
myFrame.dispose();
#SuppressWarnings("serial")
JFrame frame = new JFrame(getClass().getSimpleName()) {
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
};
frame.pack();
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
timer.stop();
}
});
myFrame = new JFrame(getClass().getSimpleName());
try {
background = new JLabel(new ImageIcon(new URL("http://cdn.bulbagarden.net/upload/thumb/6/6b/175Togepi.png/250px-175Togepi.png")));
} catch (MalformedURLException e) {
e.printStackTrace();
}
myFrame.add(background);
timer.setInitialDelay(2000);
timer.start();
myFrame.setLayout(new GridLayout(1, 1));
myFrame.setUndecorated(true);
myFrame.setAlwaysOnTop(true);
myFrame.pack();
Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
myFrame.setLocation((dim.width/2-170), dim.height/2-125);
myFrame.setVisible(true);
myFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> new SplashscreenSample().createFrame());
}
}
Or you can use the Splashscreen class...
For example:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Toolkit;
import java.net.MalformedURLException;
import java.net.URL;
import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JWindow;
public class SplashScreen extends JWindow {
private int duration;
public SplashScreen(int d) {
duration = d;
}
// A simple little method to show a title screen in the center
// of the screen for the amount of time given in the constructor
public void showSplash() {
ImageIcon icon = null;
try {
icon = new ImageIcon(new URL("http://www.cqsisu.com/data/wallpapers/5/718448.gif"));
} catch (MalformedURLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
JPanel content = (JPanel) getContentPane();
content.setBackground(Color.white);
// Set the window's bounds, centering the window
int width = icon.getIconWidth();
int height = icon.getIconHeight();
Dimension screen = Toolkit.getDefaultToolkit().getScreenSize();
int x = (screen.width - width) / 2;
int y = (screen.height - height) / 2;
setBounds(x, y, width, height);
// Build the splash screen
JLabel label = new JLabel(icon);
JLabel copyrt = new JLabel("Copyright 2002, O'Reilly & Associates", JLabel.CENTER);
copyrt.setFont(new Font("Sans-Serif", Font.BOLD, 12));
content.add(label, BorderLayout.CENTER);
content.add(copyrt, BorderLayout.SOUTH);
Color oraRed = new Color(156, 20, 20, 255);
content.setBorder(BorderFactory.createLineBorder(oraRed, 10));
// Display it
setVisible(true);
// Wait a little while, maybe while loading resources
loadResources();
setVisible(false);
}
public void loadResources() {
TestFrame tf = new TestFrame();
try {
Thread.sleep(duration);
tf.startGUI();
} catch (Exception e) {
}
}
public static void main(String[] args) {
SplashScreen splash = new SplashScreen(10000);
splash.showSplash();
}
}

Try creating and setting the frame visible in a constructor of the class.
Could it be that while your program is counting
while (elapsedTime < 2*1000)
{
if(count==0)
{
mp.launchInitiation();
}
count+=1;
elapsedTime = (new Date()).getTime() - startTime;
}
it is blocking for said 2 seconds and waiting for this method to finish, return back to the create method and then just finish that one?
it seems this could be a better comment, but i need 50 rep for some reason to comment.

JProgressBar not updating

I have made a very simple code to show it here, i have a button that should show a JDialog to check the progress status, i am using the invoke late to go through EDT and my loop isn't in the run method, so why isn't my bar updating ?
here is the code
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class JBarEx extends JFrame {
private JTextField progStatus = new JTextField("Undefined");
private JButton dialogBtn = new JButton("Show Progression dialog");
final JDialog dlg = new JDialog((JFrame) null, "prog Title", false);
final JProgressBar dpb = new JProgressBar(0, 100);
public JBarEx() {
JPanel pan = new JPanel();
dialogBtn.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
showProgress();
}
});
progStatus.setEditable(false);
pan.add(progStatus);
pan.add(dialogBtn);
setContentPane(pan);
this.setSize(200, 100);
setVisible(true);
}
public void showProgress() {
dlg.add(BorderLayout.CENTER, dpb);
dlg.add(BorderLayout.NORTH, new JLabel("prog message"));
dlg.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
dlg.setSize(300, 75);
dlg.setLocationRelativeTo(null);
dlg.setVisible(true);
for (int i = 0; i < 100; i++) {
final int ii = i;
try {
Thread.sleep(25);
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
updateBar(ii);
}
});
}
catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
public void updateBar(int newValue) {
dpb.setValue(newValue);
}
public static void main(String[] args) {
JBarEx jbx = new JBarEx();
}
}

Your showProgress method is being executed within the context of the Event Dispatching Thread. The EDT is responsible for, amongst other things, processing paint requests. This means that so long as your for-loop is executing, the EDT can not process any new paint requests (or handle the invokeLater events either) as it is blocking the EDT.
While there are any number of possible ways to solve the problem, based on your code example, the simplest would be to use a SwingWorker.
It has the capacity to allow your to execute the long running task the a background thread (freeing up the EDT), but also allows you means for publishing updates (if required) so that they can be processed in the EDT and also provides handy progress notification.
For example...
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
import javax.swing.SwingWorker;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.EmptyBorder;
public class SwingWorkerProgress {
public static void main(String[] args) {
new SwingWorkerProgress();
}
public SwingWorkerProgress() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
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 JProgressBar pbProgress;
private JButton start;
public TestPane() {
setBorder(new EmptyBorder(10, 10, 10, 10));
pbProgress = new JProgressBar();
setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.insets = new Insets(4, 4, 4, 4);
gbc.gridx = 0;
gbc.gridy = 0;
add(pbProgress, gbc);
start = new JButton("Start");
gbc.gridy++;
add(start, gbc);
start.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
start.setEnabled(false);
ProgressWorker pw = new ProgressWorker();
pw.addPropertyChangeListener(new PropertyChangeListener() {
#Override
public void propertyChange(PropertyChangeEvent evt) {
String name = evt.getPropertyName();
if (name.equals("progress")) {
int progress = (int) evt.getNewValue();
pbProgress.setValue(progress);
repaint();
} else if (name.equals("state")) {
SwingWorker.StateValue state = (SwingWorker.StateValue) evt.getNewValue();
switch (state) {
case DONE:
start.setEnabled(true);
break;
}
}
}
});
pw.execute();
}
});
}
}
public class ProgressWorker extends SwingWorker<Object, Object> {
#Override
protected Object doInBackground() throws Exception {
for (int i = 0; i < 100; i++) {
setProgress(i);
try {
Thread.sleep(25);
} catch (Exception e) {
e.printStackTrace();
}
}
return null;
}
}
}
Check out Concurrency in Swing for more details

Even if you fix the loop as others have pointed out, you'd still block the event dispatch thread. The for loop is run in showProgress() which is called from an event listener. The updates are pushed to the event queue, but that does not get processed until the loop has completed.
Use a Swing Timer instead. Something like this:
Timer timer = new Timer(25, new ActionListener() {
private int position;
#Override
public void actionPerformed(ActionEvent e) {
position++;
if (position < lastPosition) {
updateBar(position);
} else {
((Timer) e.getSource).stop();
}
}
});
timer.start();
where lastPosition would be the state where you want the progress bar to stop.
Unrelated to that bug, but a bug still, you should not create swing components outside the event dispatch thread. It's best to do it right from the start:
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JBarEx jbx = new JBarEx();
}
});
}

for (int i = 0; i < 0; i++) {
You will never enter this code so will never call the updateBar(..) method
i needs to be greater than 0 in this case. If it is 1 then updateBar will be called once, if 2 then updateBar will be called twice etc
Also rather than doing
Thread.sleep(25);
take a look at java executors as these will help with your scheduling and remove the need for the sleep

How do I use javax.swing components in an application?

Disclaimer: I am very new to Java, but I've been building .NET applications for 13 years.
I'm trying to build this Java application that does some basic calculations for tutoring. It's honestly not that big of a program, but I can't even get it to the Hello, World! state! I have a requirement that's making it difficult:
GUI should be built using javax.swing components jButton, jLabel, jTextField, jTextArea, jFrame, and jPanel.
So, I downloaded NetBeans 7.3 and created a JavaFX in Swing application. The default code obviously works but it uses Button instead of JButton:
private void createScene() {
Button btn = new Button();
btn.setText("Say 'Hello World'");
btn.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent event) {
System.out.println("Hello World!");
}
});
StackPane root = new StackPane();
root.getChildren().add(btn);
fxContainer.setScene(new Scene(root));
}
so I when I change it to use a JButton I have to also change the type the root is built from. While banging my head against the wall I found an example here (not directly related) that used the JRootPane and I thought that might work in place of the StackPane. So I refactored the code like this:
private void createScene() {
JButton btn = new JButton();
btn.setText("Say 'Hello World'");
JRootPane root = new JRootPane();
root.getContentPane().add(btn);
fxContainer.setScene(new Scene(root));
}
and that code is fine except for fxContainer.setScene(new Scene(root)); because root isn't a Parent.
FYI, the application class implements JApplet and has a main and init that looks like this:
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");
} catch (Exception e) {
}
JFrame frame = new JFrame("Tutoring Calculator");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JApplet applet = new TutoringCalculator();
applet.init();
frame.setContentPane(applet.getContentPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
applet.start();
}
});
}
#Override
public void init() {
fxContainer = new JFXPanel();
fxContainer.setPreferredSize(new Dimension(JFXPANEL_WIDTH_INT, JFXPANEL_HEIGHT_INT));
add(fxContainer, BorderLayout.CENTER);
// create JavaFX scene
Platform.runLater(new Runnable() {
#Override
public void run() {
createScene();
}
});
}
How can I fulfill the requirement stated above? Am I really going about this whole thing the wrong way?
SSCCE
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package tutoringcalculator;
import java.awt.BorderLayout;
import java.awt.Dimension;
import javafx.application.Platform;
import javafx.embed.swing.JFXPanel;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.StackPane;
import javax.swing.JApplet;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JRootPane;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
/**
*
* #author Owner
*/
public class TutoringCalculator extends JApplet {
private static final int JFXPANEL_WIDTH_INT = 300;
private static final int JFXPANEL_HEIGHT_INT = 250;
private static JFXPanel fxContainer;
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");
} catch (Exception e) {
}
JFrame frame = new JFrame("Tutoring Calculator");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JApplet applet = new TutoringCalculator();
applet.init();
frame.setContentPane(applet.getContentPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
applet.start();
}
});
}
#Override
public void init() {
fxContainer = new JFXPanel();
fxContainer.setPreferredSize(new Dimension(JFXPANEL_WIDTH_INT, JFXPANEL_HEIGHT_INT));
add(fxContainer, BorderLayout.CENTER);
// create JavaFX scene
Platform.runLater(new Runnable() {
#Override
public void run() {
createScene();
}
});
}
private void createScene() {
JButton btn = new JButton();
btn.setText("Say 'Hello World'");
JRootPane root = new JRootPane();
root.getContentPane().add(btn);
fxContainer.setScene(new Scene(root));
}
}

This code works either as an applet or desktop app. here:
import java.awt.BorderLayout;
import java.awt.Dimension;
import javax.swing.*;
// <applet code=TutoringCalculator width=400 height=400></applet>
public class TutoringCalculator extends JApplet {
// The size of an applet is set by the HTML!
//private static final int JFXPANEL_WIDTH_INT = 300;
//private static final int JFXPANEL_HEIGHT_INT = 250;
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame("Tutoring Calculator");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JApplet applet = new TutoringCalculator();
applet.init();
frame.setContentPane(applet.getContentPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
applet.start();
}
});
}
private JPanel swingContainer;
#Override
public void init() {
swingContainer = new JPanel(new BorderLayout());
add(swingContainer, BorderLayout.CENTER);
createScene();
}
private void createScene() {
JButton btn = new JButton();
btn.setText("Say 'Hello World'");
JRootPane root = new JRootPane();
root.getContentPane().add(btn);
swingContainer.add(root);
}
}
I could not be bothered figuring why you are using a RootPane so I left that as is.
Further tips
The spec. mentions JFrame but not JApplet. Since applets are significantly harder to develop, debug and deploy, I suggest you focus entirely on getting it working in a frame.
For frame positioning, you cannot go by setLocationByPlatform(true). See this answer for demo.

Can we create GUI for standalone application using html and javascript?

I have a Java program which until now used to get the input from command line and then proceed accordingly.
Now, I want to have a basic GUI for this. It will need a few buttons which will trigger the events. I am experienced in HTML and JavaScript. Is it possible to write in HTML (or similar syntax) to generate the GUI?
I don't want to go in Swing and awt solution, because I would rather concentrate on the main program than on the GUI.

Here's another alternative. See also How to Use HTML in Swing Components.
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.io.File;
import javax.swing.AbstractAction;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
/**
* #see http://stackoverflow.com/a/10067256/230513
* #see http://stackoverflow.com/a/7454691/230513
*/
public class Pathfinder extends JPanel {
private static final int TEXT_SIZE = 32;
private JTextField srcField = new JTextField(TEXT_SIZE);
private JTextField dstField = new JTextField(TEXT_SIZE);
private JTextField valueField1 = new JTextField(TEXT_SIZE);
private JTextField valueField2 = new JTextField(TEXT_SIZE);
private String srcPath, dstPath, value1, value2;
public Pathfinder() {
super(new GridLayout(0, 1));
this.add(createPathPanel("Source Directory", srcField));
this.add(createPathPanel("Target Directory", dstField));
this.add(createFieldPanel("Some Value:", valueField1));
this.add(createFieldPanel("Another Value:", valueField2));
JPanel submitPanel = new JPanel();
submitPanel.add(new JButton(new AbstractAction("Submit") {
#Override
public void actionPerformed(ActionEvent e) {
srcPath = srcField.getText();
dstPath = dstField.getText();
value1 = valueField1.getText();
value2 = valueField2.getText();
process();
}
}));
this.add(submitPanel);
}
private void process() {
// see ProcessBuilder http://stackoverflow.com/questions/5740390
System.out.println(srcPath);
System.out.println(dstPath);
System.out.println(value1);
System.out.println(value2);
}
private JPanel createPathPanel(String name, final JTextField jtf) {
JPanel panel = new JPanel(new FlowLayout(FlowLayout.TRAILING));
panel.add(new JButton(new AbstractAction(name) {
#Override
public void actionPerformed(ActionEvent e) {
JFileChooser jfc = new JFileChooser(
new File(System.getProperty("user.dir")));
jfc.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
int result = jfc.showOpenDialog(Pathfinder.this);
if (result == JFileChooser.APPROVE_OPTION) {
jtf.setText(jfc.getSelectedFile().getPath());
}
}
}));
panel.add(jtf);
return panel;
}
private JPanel createFieldPanel(String name, JTextField jtf) {
JPanel panel = new JPanel(new FlowLayout(FlowLayout.TRAILING));
panel.add(new JLabel(name));
panel.add(jtf);
return panel;
}
private void display() {
JFrame f = new JFrame("Pathfinder");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(this);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
public static void main(final String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
Pathfinder pf = new Pathfinder();
if (args.length > 0) {
pf.srcPath = args[0];
pf.dstPath = args[1];
pf.process();
} else {
pf.display();
}
}
});
}
}

I want to have a basic GUI for this. It will need a few buttons which will trigger the events.
This 'basic GUI' goes slightly beyond the spec. to add an output area.
import java.awt.*;
import javax.swing.*;
class SimpleEventGUI {
SimpleEventGUI() {
JPanel gui = new JPanel(new BorderLayout());
JToolBar toolBar = new JToolBar();
for (int ii=1; ii<6; ii++) {
toolBar.add(new JButton("Event " + ii));
if (ii%2==0) {
toolBar.addSeparator();
}
}
gui.add(toolBar, BorderLayout.NORTH);
gui.add( new JScrollPane(new JTextArea(5,30)), BorderLayout.CENTER );
JOptionPane.showMessageDialog(null, gui);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new SimpleEventGUI();
}
});
}
}

You may consider Google Web Toolkit with Window Builder which allow you to build a rich internet interface using Java and interact with the existing logic.
If you want something quick, you can build a Swing GUI using Window Builder