Java application problem

Question

I am using JDK1.4 and working on Windows Xp.
I have written a code for application in java as follows:
import javax.swing.*;
public class sample
JPanel panel;
static JFrame frame;
JButton but;
public sample()
frame=new JFrame("frame");
panel=new JPanel();
frame.getContentPane().add(panel);
but=new JButton("click");
panel.add(but);
public static void main(String args[])
sample s=new sample();
frame.setSize(300,300);
frame.setVisible(true);
on executing program application window has appeared and it ran properly.
Then I closed that application window.But after that in command prompt window curser was just blinking and it was not allow to enter also.
I have tried pressing CTRL+C also.But situation in command prompt was same i.e curser in command prompt was just blinking.
Then I closed cmd window ;but one error has occured saying that cmd window can not close .
My friend has told me that she is also having windows xp and JDK1.4 ; ctrl+c is working properly in her command prompt.She has written the above same code in her computer and it executes properly.
Even though she has not written following statement:
"frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);"
when she exits from application window ,her cmd window gave same problem of only blinking curser.But when she press CTRL+C ; her command prompt starts responding by giving root.But my command prompt is not giving
positive responce to "ctrl+c" when I am exiting java application.
Is it possible to solve this problem without giving statement
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); ?
Why my command prompt is not responding to CTRL+c?
How can I tackle this problem ?
Is there any other key which can be used in command prompt of Windows Xp?

Answer 1

Is it possible to solve this problem without giving
statement
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
?this is because Swing have started some non-daemon helper threads for its internal purposes and the default close operation for frame is just HIDE_ON_CLOSE. So, the system will not exit because those non-daemon thread still not terminated.
What is the problems setting the default close operation to JFrame.EXIT_ON_CLOSE ?