We Keep Coding

Java JFrame freezing

I have this simple java application using swing. However the moment I execute the program the frame will appear but I won't be able to click anywhere and the button only appears after a few seconds. I am very new to javas Swing library so I could be missing something, however from what I've read this code shouldn't be causing any issues.
import java.awt.Graphics;
import java.awt.image.BufferStrategy;
import java.awt.FlowLayout;
import javax.swing.*;
public class Game {
public static void main(String[] args) {
JFrame frame = new JFrame("JFrame Example");
JPanel panel = new JPanel();
panel.setLayout(new FlowLayout());
JLabel label = new JLabel("This is a label!");
JButton button = new JButton();
button.setText("Press me");
panel.add(label);
panel.add(button);
frame.add(panel);
frame.setSize(300, 300);
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}
EDIT
So I reinstalled my jdk but discovered this: if my browser is running when I execute the above code it will hang and freeze, however if I close my browser it runs as expected. But I can't start my browser until I kill my application so it seems something is wrong with my install as these shouldn't be using the same resources?
EDIT
Solved my problem: had multiple versions of jdk and jre install so unstalled both and then installed latest versions and everything seems to be working!

You need to create UI under UI dispatching thread:
SwingUtilities.invokeLater(new Runnable() {
public void run() {
// code to create UI or call to function that creates the UI
}
});
Java 8 style:
SwingUtilities.invokeLater(()->{
// Your UI code
});
If you don't use that idiom then the UI can't be partially created in inconsistent state, see Creating UI in swing:
almost all code that creates or interacts with Swing components must
run on the event dispatch thread
You can also use invokeAndWait is you need to block until the UI is created.

Adding a JPanel manually in NetBeans 7.1

I am trying to add a JPanel manually to a JPanel that was created via the Graphic Designer.
Since i can't edit in the Generated code i have no idea if i can do that.
private void jMenuItem2ActionPerformed(java.awt.event.ActionEvent evt) {
newBall2 = new BasketBall("BasketBall",20,400);
MainpaintPanel mp = new MainpaintPanel();
this.add(mp);
}
in this code the mp Panel is created successfully but it doesn't show where it's added.
i think it's related to the default Layout of the netBeans but it could be something else.
Thanks in Advance.

you could also try using the ".setVisible(true)" and "setLocationRelativeTo(component c)" methods of the panel

I can't run a JFrame due to compiler errors & warnings

*I'm sorry for all of the trouble I may have caused you guys.
So, I am extremely new to programming with just a little experience in Java and Python. I was trying to make a program that would open a frame. In this frame there would be a button. When clicked, this button would play a song. I used a "recommended" code from YouTube. The code would begin to run, and then just stop. No frame would ever even appear. I showed it to a more experienced friend of mine. He said that the exact code ran just fine on his computer. I then sent him a screenshot of my project displayed on eclipse. He said that my JRE seemed to be missing some files. I tried a code that would just create a window, but it had the same problem. I am not sure what the JRE is, but I currently have JRE7. I don't know what I should do to fix this. Please help.
Error List
Severity and Description Path Resource Location Creation Time Id
The public type TopLevelWindow must be defined in its own file TGProject/src Frame.java line 4 1390698271752 73
The type TopLevelWindow is already defined TGProject/src TopLevelWindow.java Unknown 1390699351785 77
The method show(boolean) from the type Component is deprecated TGProject/src sound.java line 16 1390702839525 78
A link to the what my eclipse shows.
http://gyazo.com/3afdfa4f6750420f4e46deec40389340
A link to my Java file.
http://gyazo.com/257481d4ae9e2bb1d0ca93415a6c547e
Code for music
import java.awt.event.*;
import javax.swing.*;
import sun.audio.*;
import java.io.*;
public class sound {
public static void main(String[] args)
{
JFrame frame = new JFrame();
frame.setSize(200,200);
JButton button = new JButton("Click me");
frame.add(button);
button.addActionListener(new AL());
//this is outdated, but should still work
frame.show(true);
}
public static class AL implements ActionListener{
public final void actionPerformed(ActionEvent e) {
music();
}}
public static void music()
{
AudioPlayer MGP = AudioPlayer.player;
AudioStream BGM;
AudioData MD;
ContinuousAudioDataStream loop = null;
try{
BGM = new AudioStream(new FileInputStream("Jambi.mp3"));
MD = BGM.getData();
loop = new ContinuousAudioDataStream(MD);
}catch(IOException error) {}
MGP.start(loop);
}
}
Code for Frame
import java.awt.*;
import javax.swing.*;
// Create a simple GUI window
public class TopLevelWindow {
private static void createWindow() {
//Create and set up the window.
JFrame frame = new JFrame("Simple GUI");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JLabel textLabel = new JLabel("I'm a label in the window",SwingConstants.CENTER);
textLabel.setPreferredSize(new Dimension(300, 100));
frame.getContentPane().add(textLabel, BorderLayout.CENTER);
//Display the window.
frame.setLocationRelativeTo(null);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
createWindow();
}
}

Error 1
The public type TopLevelWindow must be defined in its own file
You either need to change.
public class TopLevelWindow {
To:
class TopLevelWindow {
Or do as reported and declare a new class for TopLevelWindow
Error 2
The type TopLevelWindow is already defined
I'm not sure what that means, but it might be solved by fixing the first problem.
Warning 3
The method show(boolean) from the type Component is deprecated
For any deprecation warning, go to the relevant method in the Java Docs. They should give details about what to use instead.
Tips
Compile often and ask as soon as you have a single error you do not understand.
Don't try to run code that shows problems in that window. Only experts should even try that.
You catch more flies with honey than with vinegar. Don't take the tone you did with Jayan, even if you think they are being harsh. People help for free, so have little time for questions that do not come up to standard. It might have been better to explain to the person that the question had now changed. Perhaps that would have made no difference to them, but either way, adding that kind of reply discourages everyone from helping.
"I used a "recommended" code from YouTube." Don't use YouTube videos to learn programming. They are often old, and in this case, they are using classes in the sun package for which there were better replacements since Java 1.3.

If you're really that new to programming, I would suggest to use an IDE (development environment) like for instance Netbeans or Eclipse and create a new JFrame form. You can then use the design view to graphically design your interface, IE drag your button on the screen. No need to go around programming frames. All you need to code is the implementation; what happens after you click the button.
After you posted the code, I had another look and this is what I've found:
Both classes have main methods. I ran both and each opened up a different window for me. Typically, you'll only want one main method. It's the main method! It's the starting point of your program and you can of course only have one starting point. At this time, your program is going to do two different things depending on what main method you run.
Still, this isn't your issue, because both mains are running for me. I think you must have the wrong version of java or something?

What I think you did is you pasted all that code into a file that wasn't called exacly "TopLevelWindow". If so, do that. I think your problem will go away.
Remember to only have one class per file, (barring inner classes; not something to concern yourself with as a beginner).

Swing Application Window not responding on Mac

I'm trying to get a basic Swing Application to run on my Mac OS X 10.8.2 (Java version 1.6.0_37) machine, and every time I try to run it from Eclipse, the frame appears, but I can't interact with it.
I've tried to start from a basic, clean slate where I create a new Swing Application Window project in Eclipse (WindowBuilder->Swing Designer->Application Window). This generates the following skeleton code:
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JButton;
import java.awt.BorderLayout;
public class Test {
private JFrame frame;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
Test window = new Test();
window.frame.setVisible(true);
window.frame.pack();
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public Test() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frame = new JFrame();
frame.setBounds(100, 100, 450, 300);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JButton btnPress = new JButton("Press");
frame.getContentPane().add(btnPress, BorderLayout.CENTER);
}
}
Everything seems to be fine, but when I run this from Eclipse, the frame doesn't let me interact with any components (in my non-example code, there are buttons and tabs).
Also, in the console, I see things like:
2012-11-09 14:30:27.624 java[8107:707] [Java CocoaComponent compatibility mode]: Enabled
2012-11-09 14:30:27.626 java[8107:707] [Java CocoaComponent compatibility mode]: Setting timeout for SWT to 0.100000
Is there some Mac-specific setting that I have to change? (I'm using the latest default Mac JRE)

The program runs fine on my machine under OSX, but it could be the missing
window.frame.pack();
Have you tried this?
Test window = new Test();
window.frame.pack();
window.frame.setVisible(true);

I had the same problem when using the DJ Swing library in my application (it uses SWT). Interestingly, the problem occurred even though I didn't initialise DJ Swing explicitly. It now works because I have added DJ Swing initialisation:
public class SwingAppTest {
public static void main(String[] args) {
NativeInterface.open();
UIUtils.setPreferredLookAndFeel();
SwingUtilities.invokeLater(new Runnable() {
public void run() {
JFrame frame = new JFrame("Example");
frame.getContentPane().setLayout(new BorderLayout());
frame.setPreferredSize(new Dimension(400, 200));
frame.setBounds(0,0,200,200);
frame.setTitle("blah");
JButton blah = new JButton("blah");
blah.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
System.out.println("button clicked");
}
});
frame.getContentPane().add(blah, BorderLayout.CENTER);
frame.setVisible(true);
}
});
NativeInterface.runEventPump();
}
}

Apple is no longer supporting Java in is operating systems after 10.6:
Apple not committing to Java support in Mac OS X 10.7
seems like missing or incompatible library files in the JRE.

that is weird. I tried your sample (no linux) and don't see any problem there.
So as Wayne mentioned, might be macos issue.
Btw, what is your java version you're using?
On the other hand problem might be in the code you didn't share with us => hard to guess :)
EDIT: OK, so it seems you're playing "guess what I have in my code" game with us :) As my assumption is that code not shown causes problem.
It reminds me of some of these Poiroit/Agatha Christie detective stories, where just a little detail might have significant impact on the reality.
This is the reason for my theory:
code shown uses Java swing library (import javax.swing. ...) + Awt (import java.awt. ...) - this combonation is a common use case, however
the error message you shared shows SWT library error (Setting timeout for SWT to 0.100000)
So to me it seems like you're mixing things that should never be mixed.
As Swing is java UI library that is completely OS independent (originally Sun made) that is built on top of Awt. However SWT is completely different java UI library which is kind of mix of native calls with java on it (originally IBM made).
Therefor I'd suggest to double check your code and make sure that if you use JFrame, the only library components you have there are from Swing (javax.swing....) / Awt (java.awt. ...).

I've been knocking my head against a wall for days trying to get this working and finally found the answer:
'It's solved now - it was just a case of removing swt.jar from the project dependencies.'
Hey presto!!!!

In my case, I was trying to code a game where I used jPanel. I needed to override the paint method and added pack(); to the main and it finally showed me what I was trying to draw.

Why my Swing based GUI application is not responding?

I am trying to create my first GUI application using (Java + Eclipse + Swing). This is my code:
import java.awt.*;
import javax.swing.*;
public class HelloWorldSwing extends JFrame {
JTextArea m_resultArea = new JTextArea(6, 30);
//====================================================== constructor
public HelloWorldSwing() {
//... Set initial text, scrolling, and border.
m_resultArea.setText("Enter more text to see scrollbars");
JScrollPane scrollingArea = new JScrollPane(m_resultArea);
scrollingArea.setBorder(BorderFactory.createEmptyBorder(10,5,10,5));
// Get the content pane, set layout, add to center
Container content = this.getContentPane();
content.setLayout(new BorderLayout());
content.add(scrollingArea, BorderLayout.CENTER);
this.pack();
}
//============================================================= main
public static void main(String[] args) {
JFrame win = new HelloWorldSwing();
win.setTitle("TextAreaDemo");
win.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
win.setVisible(true);
}
}
The code was taken from here.
When I run the application from Eclipse the expected window appears (So, it's good. I see what I want to see). However, when I try to close the window or try to write something in the text area the program freezes. The OS writes me that program is not responding (I try it on Ubuntu).
Can anybody help me to find the reason of the problem?
Thank you in advance for any help.

I'm sure this doesn't have to do with the code, as others have found the code runs just fine on their machines - which points to a machine specific issue. From within Eclipse, make sure it is setup to use the expected JDK/JRE. However, before worrying about how Eclipse is handling your situation, I'd run things by hand first - especially since you've got a very simple class.
I would check to ensure that you're using the expected compiler and runtime. On Linux:
which javac
which java
If they're both what you expect, do the following:
javac HelloWorldSwing.java
java HelloWorldSwing
If you get a similar problem, then you know it's not the Eclipse configuration and it's something else. If you're not using the latest JDK, upgrade to the latest. If you're already at the latest, it could be a display driver. Do other JAVA swing programs work on this computer? I'm sure you could find some on the net, download an app already packaged as a jar and try running it.

did you try using the eventdispatcherthread to view the JFrame?
something like:
public static void main(String[] args){
SwingUtilities.invokeLater(new Runnable(){
public void run(){
createAndViewJFrame();
}
});
}
public void createAndViewJFrame(){
JFrame win = new HelloWorldSwing();
win.setTitle("TextAreaDemo");
win.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
win.setVisible(true);
}
then your frame would be shown by the swing dispatcher thread.
hope it helped, although im just guessing...
Update: as commenters pointed you i f**ed up the invokeLater() call. I just edited this post to correct that. Thanx go to yishai & willcodejavaforfood for pointing it out!
frank

You need to catch the exit event and
respond with a System.exit( 0 );
You should be able to find that in
most swing examples online.
wrong stuff... sorry... coffee... argh....