Question

I have implemented a timer to invoke my alert() method. The duration of the timer is retrieved from the database. When I set the duration to 1 minute, the timer invokes alert() every one minute. When I set the duration again for 5 minutes, the 1 minute timer does not stop. So now I have 2 running timers. How can I remove the previous timer? Thanks.

private void getDuration() 
{       
    durationTimer = new javax.swing.Timer(durationDB, new ActionListener() 
    {               
        public void actionPerformed(ActionEvent e) 
        {       
            alert();      
        }     
    });                 
    durationTimer.stop();

    try
    {   
        // Connection to the database
        Class.forName("com.mysql.jdbc.Driver");
        Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/smas","root","root");
        Statement stmt = con.createStatement();
        ResultSet rs = stmt.executeQuery("SELECT * FROM alertduration");    

        while (rs.next()) 
        {
            durationDB = rs.getInt("duration");     
        }   

        con.close();            
    }

    catch(Exception ea)
    {
        JOptionPane.showMessageDialog(watchlist, "Please ensure Internet Connectivity ", "Error!", JOptionPane.ERROR_MESSAGE);
    }           


    durationTimer = new javax.swing.Timer(durationDB, new ActionListener() 
    {               
        public void actionPerformed(ActionEvent e) 
        {       
            alert();      
        }     
    });         

    durationTimer.start();

Answer 1

Call the stop() method when you are finished with the first timer. It may also be worth making your timer global and reusing it rather than creating a new one every time the duration changes. See: http://docs.oracle.com/javase/6/docs/api/javax/swing/Timer.html

Example:

durationTimer = new javax.swing.Timer(duration, new ActionListener() {               
    @Override
    public void actionPerformed(ActionEvent e) {       
        alert();
    }     
});                 

durationTimer.start();

//wait for duration to change
durationTimer.stop();
durationTimer.setDelay(duration);
durationTimer.start();