I wrote a simple program with java swing which suppose to start another thread and in that thread a JForm will show up when I click a button. But JForm is not showing up... I used if (Thread.currentThread().getName() == "Thread1") to do the specific task for that thread, when I comment that program runs perfectly, I can't understand why it is not going to the if block... Please someone help me with this...
Thanks in advance!
Here is the code,
public class Test extends JFrame implements ActionListener {
JPanel panel;
JButton button;
public Test() {
setVisible(true);
setSize(300, 300);
setDefaultCloseOperation(DISPOSE_ON_CLOSE);
panel = new JPanel();
button = new JButton("click me");
button.addActionListener(this);
panel.add(button);
add(panel, BorderLayout.CENTER);
}
public static void main(String[] args) {
Test tst=new Test();
}
#Override
public void actionPerformed(ActionEvent arg0) {
if(arg0.getSource()==button){
System.out.println("test");
test2 test = new test2();
Thread tr1 = new Thread(test);
tr1.setName("Thread1");
tr1.start();
}
}
}
class test2 implements Runnable{
public void run() {
//if (Thread.currentThread().getName() == "Thread1") {
System.out.println("inside thread");
JFrame frame2=new JFrame();
frame2.setVisible(true);
frame2.setSize(300, 300);
frame2.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
//}
}
}
Try using getName().equals("Thread1") instead.
equals compares the strings, == checks if the two strings are the same object.
Try:
if (Thread.currentThread().getName().equals("Thread1"))
or
if (Thread.currentThread().getName().compareTo("Thread1") > 0)
why do you have that check for the current threads name anyway? That thread will be the only one to call that method anyway.
You must not compare String values using == as it checks for object identity. You should use Thread.currentThread().getName().equals("Thread1") instead.
You should not interact with any Swing/AWT components outside of the Event Dispatch Thread!
Related
This is a very simplified version of my code to get a better understanding of what I'm doing wrong here. The GUI freezes if the button is pressed. I need to be able to run a while loop if the button is pressed without freezing.
class obj1 extends Thread{
public void run(){
while(true) {
System.out.println("this thread should run when the button is pressed and I should be able to press another button");
}
}
}
class GUI extends Thread{
JFrame frame = new JFrame();
JButton button = new JButton("test1");
JButton button2 = new JButton("test2");
JPanel panel = new JPanel();
String command;
public void run() {
frame.setVisible(true);
panel.add(button);
panel.add(button2);
frame.add(panel);
frame.pack();
buttonOnAction();
}
public void buttonOnAction(){
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
obj1 one = new obj1();
one.start();
one.run();
}
});
button2.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
obj1 one2 = new obj1();
one2.start();
one2.run();
}
});
}
}
public class Main{
public static void main(String args[]){
GUI gui = new GUI();
gui.start();
gui.run();
}
}
Why does the GUI freeze?
Don't call run() directly on your Thread object. This immediately executes the run() method and doesn't spawn a new thread. Instead, just call start() as you have and let the system create the thread and call run() when it decides to.
It is also worth pointing out that the proper way to schedule graphical work in Swing is to make sure it ends up on the event dispatch thread. To do this properly, use SwingUtilities#invokeLater(Runnable), which will not wait for the work to complete, or SwingUtilities#invokeAndWait(Runnable), which will.
I have two JFrame based windows: SeatLayout and BillSummary. I need to get the seatnumber from the SeatLayout frame and display it in BillSummary but the variable scope is limited to the first frame.
How can I do this?
Using multiple JFrame is a bad practice and it should be avoided.
Reason being, it will add more problems in the future and it will be nightmare to maintain.
To answer your question , how to pass variable from your parent(JFrame) to a child(JDialog) .This can achive by using JDialog.
I am going to run through an example.
lets say, your BillSummary.java is ....
//BillSummary Class
public class billSummary {
JFrame frame;
billSummary(JFrame frame) {
this.frame = frame;
}
public void launchbillSummary(int seatNumber) {
// Create a dialog that suits your ui , you can use JPanel as your layout container
JDialog dialog = new JDialog(frame, "Bill Summary", true);
dialog.setLayout(new BorderLayout());
dialog.setSize(100, 100);
dialog.add(new JLabel(Integer.toString(seatNumber)), BorderLayout.CENTER);
dialog.setVisible(true);
}
}
Your seatLayout.java
public class seatLayout {
seatLayout(){
//Lets say you have seleted seat number 10
int defaultSeatNumber = 10;
//Lets say you have a button and when it is clicked , you pass the data to billsummary page
JButton enter = new JButton("Enter");
//Your seatLayout GUI
JFrame frame = new JFrame("seat layout");
frame.setSize(300,300);
frame.add(enter);
enter.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent arg0) {
//Do your passing of data/ price of calculation here
//You pass the data that to your custom dialog -> Bill summary
new billSummary(frame).launchbillSummary(defaultSeatNumber);
}
});
frame.setVisible(true);
}
public static void main(String[] args){
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new seatLayout();
}
});
}
}
I hope this help and answers your question. Good luck :)
I'm working on this program and I ran into another issue. I have a Jframe with a JLabel that I wish for it to change text from one thing to another. However, when I try to do that it doesnt show me the text changing, rather the last text I set it to.
How do I get my JLabel to cycle through text SLOWLY?
I'm trying a wait method to make the program go slowly so I can see if I can make it cycle through, but that doesnt seem to be working.
it would be helpful if someone could edit my code or make their own example of how to do this, THANKS!
public class CreditGraphics {
public String cardNum;
public JFrame frame;
public JPanel panel;
public JLabel label;
public JTextField text;
public CreditGraphics() {
synchronized(this){
try {
frame = new JFrame("HI");
panel = new JPanel();
label = new JLabel();
text = new JTextField(16);
panel.add(label);
panel.add(text);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
panel.setPreferredSize(new Dimension(500, 500));
frame.getContentPane().add(panel);
frame.pack();
frame.setVisible(true);
wait(4000);
label.setText("Hi");
wait(4000);
frame.revalidate();
frame.repaint();
label.setText("Hello");
frame.revalidate();
frame.repaint();
text.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
cardNum = text.getText();
}
});
}
catch(InterruptedException e) {
e.printStackTrace();
}}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new CreditGraphics();
}
});
}
public void checkCard(){
}
}
As suggested by #trashgod use Swing Timer that is more suitable for swing application to perform a task once, after a delay or to perform a task repeatedly.
sample code:
private Timer timer;
...
label.setText("Hi");
// delay of 4 seconds
timer=new Timer(4000,new ActionListener() {
#Override
public void actionPerformed(ActionEvent arg0) {
label.setText("Hello");
// timer.stop(); // stop the timer if repeated mode is on
}
});
timer.setRepeats(false); // you can turn-on it if needed
timer.start();
Note:
There is no need to call frame.repaint() and frame.revalidate() in this case.
Override getPreferredSize() to set the preferred size of the JPanel in case of custom painting.
sample code:
JPanel panel = new JPanel() {
#Override
public Dimension getPreferredSize() {
return new Dimension(..., ...);
}
};
read more...
Do not use Thread.sleep() or wait() as it will freeze your Swing application.
Instead you should use a javax.swing.Timer
See the Java tutorial How to Use Swing Timers and Lesson: Concurrency in Swing for more information and examples.
I am a novice as already stated and looking to create a button to close the program out. I am not talking about making sure the typical window close (Red X) terminates the program. I wish to make an additional button within my frame that when clicked will terminate the program as well.
You can add an ActionListener to your button which, upon action being performed, exits from the JVM.
yourButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
System.exit(0);
}
});
If you have set up the main application frame's (JFrame) defaultCloseOperation to JFrame.EXIT_ON_CLOSE then simply calling the frame's dispose method will terminate the program.
JButton closeButton = JButton("Close");
closeButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
yourReferenceToTheMainFrame.dispose();
}
});
If not, then you will need to add to the actionPerformed method a call to System.exit(0);
import java.awt.GridLayout;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.EmptyBorder;
public class GoodbyeWorld {
GoodbyeWorld() {
final JFrame f = new JFrame("Close Me!");
// If there are no non-daemon threads running,
// disposing of this frame will end the JRE.
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
// If there ARE non-daemon threads running,
// they should be shut down gracefully. :)
JButton b = new JButton("Close!");
JPanel p = new JPanel(new GridLayout());
p.setBorder(new EmptyBorder(10,40,10,40));
p.add(b);
f.setContentPane(p);
f.pack();
f.setLocationByPlatform(true);
f.setVisible(true);
ActionListener closeListener = new ActionListener(){
#Override
public void actionPerformed(ActionEvent arg0) {
f.setVisible(false);
f.dispose();
}
};
b.addActionListener(closeListener);
}
public static void main(String[] args) {
Runnable r = new Runnable() {
#Override
public void run() {
new GoodbyeWorld();
}
};
SwingUtilities.invokeLater(r);
}
}
If you are extending the org.jdesktop.application.Application class (Netbeans would do that) you could invoke exit() in your app class, so:
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
yourApp.exit();
}
});
I want to animate a JFrame to become half-size when i press a button in my programme. I think the easiest way is putting the current bounds of JFrame into a timer and decrease bounds 1 by 1 when the timer running.But when I declare a new timer in netbeans IDE it will looks like this.
Timer t = new Timer(5,new ActionListener() {
public void actionPerformed(ActionEvent e) {
//inside this I want to get my Jframe's bounds like this
// int width = this.getWidth();---------here,"this" means the Jframe
}
}
});
But the problem is in here "this" not refering to JFrame.And also I cant even create a new object of my JFrame.Because it will give me another window.Can anyone help me solve this problem ?.
Try
int width = Foo.this.getWidth();
where Foo subclasses JFrame.
I want to animate a JFrame to become half-size when i press a button in my programme
So when you click the button you have access to the button. Then you can use:
SwingUtilities.windowForComponent( theButton );
to get a reference to the frame.
So now when you create the ActionListener for the Timer you can pass in the Window as an argument for the ActionListener.
Edit:
The suggestion by mre is simple and straight forward and easy to use in many cases (and probably the better solution in this case).
My suggestion is a little more complicated but it was introducing you to the SwingUtilities method which will eventually allow you to write more reusable code that could potentially be used by any frame or dialog you might create.
A simple example would be something like:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class AnimationSSCCE extends JPanel
{
public AnimationSSCCE()
{
JButton button = new JButton("Start Animation");
button.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
JButton button = (JButton)e.getSource();
WindowAnimation wa = new WindowAnimation(
SwingUtilities.windowForComponent(button) );
}
});
add( button );
}
class WindowAnimation implements ActionListener
{
private Window window;
private Timer timer;
public WindowAnimation(Window window)
{
this.window = window;
timer = new Timer(20, this);
timer.start();
}
#Override
public void actionPerformed(ActionEvent e)
{
window.setSize(window.getWidth() - 5, window.getHeight() - 5);
// System.out.println( window.getBounds() );
}
}
private static void createAndShowUI()
{
JFrame frame = new JFrame("AnimationSSCCE");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add( new AnimationSSCCE() );
frame.setSize(500, 400);
frame.setLocationRelativeTo( null );
frame.setVisible( true );
}
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
createAndShowUI();
}
});
}
}
Of course you would want to stop the timer when the winow reaches a certain minimum size. I'll leave that code up to you.