How can i send an event while the program is in a loop?

Question

I work at a project and i need to understand very well how event-driven programming works. I've read a lot in the last few days and i understood how this is working but i cant figure some things out.

In a class called Application i got this:

public void Simulate() throws InterruptedException {


    int i = 0;
    while (1 == 1) {

        System.out.println(i);
        Thread.sleep(1000);
        i++;
    }

}

And i have this class:

import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.BorderLayout;
import javax.swing.JButton;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class Visual {

    private JFrame frame;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    Visual window = new Visual();
                    window.frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the application.
     */
    public Visual() {
        initialize();
    }

    /**
     * Initialize the contents of the frame.
     */
    private void initialize() {
        frame = new JFrame();
        frame.setBounds(100, 100, 472, 381);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel panel = new JPanel();
        frame.getContentPane().add(panel, BorderLayout.NORTH);

        JButton btnStart = new JButton("Start");

        btnStart.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent arg0) {
                Application app = new Application();
                try {
                    app.Simulate();
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        });

        **JButton print = new JButton("Print");
        print.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                System.out.println("random text");
            }
        });**
        panel.add(print);
        panel.add(btnStart);
    }

}

What i want to do is when i run this program, i want to pres the putton Start to start the loop in the simulate method and then i want to press the button print, to print some random text while the counter is still running. The problem is that after i pres the start button, the print button becomes unavailable, and cant be pressed anymore. How can i solve this?

Answer 1

For buttons don't use addMouseListener, use addActionListener and override actionPerformed method, to be able to print your number while the loop is running, try to call your simulate method using new thread. Change your Visual class to the followng example:

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Visual {

    private JFrame frame;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    Visual window = new Visual();
                    window.frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the application.
     */
    public Visual() {
        initialize();
    }

    /**
     * Initialize the contents of the frame.
     */
    private void initialize() {
        frame = new JFrame();
        frame.setBounds(100, 100, 472, 381);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel panel = new JPanel();
        frame.getContentPane().add(panel, BorderLayout.NORTH);

        JButton btnStart = new JButton("Start");

        btnStart.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent arg0) {
                Application app = new Application();

                (new Thread(new Runnable() {
                    public void run() {
                        try {
                            app.Simulate();
                        } catch (InterruptedException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                    }
                })).start();

            }
        });

        JButton print = new JButton("Print");
        print.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                System.out.println("random text");
            }
        });
        panel.add(print);
        panel.add(btnStart);
    }
}