计时器实用程序不会为JLabel添加新行

Question

Why is that When I user the Timer.util the JLabel wont allign with my String that I inserted in my JTextPane? But when I use the Timer it Allign. I need the Timer.util for my database so it wont lag.

Here is the image when I use the Timer swing

Timer t2 = new Timer(250,new ActionListener(){

        public void actionPerformed(ActionEvent arg0) {

            fetchMessageData2();
        }
    });
    t2.start();


public static void fetchMessage(JTextPane jtep,StyledDocument sd,int count  )
{

    try{

    String query = "SELECT members.username, message FROM chat JOIN members ON    chat.user_id = members.id WHERE message_id > "+count+"";
    rs = st.executeQuery(query);
    while(rs.next())
    {

        try {
            final JLabel jp = new JLabel(rs.getString("username")+ "\n");
            jp.setAlignmentY(0.75f);
            jp.setFont(new Font("arial",Font.BOLD,16));
            jtep.insertComponent(jp);
            sd.insertString(sd.getLength(), ": "+rs.getString("message")+ "\n", MainPanel.sas);
        } catch (BadLocationException e1) {

            e1.printStackTrace();
        }


        MainPanel.count++;}

    }catch(Exception ex){System.out.print(ex);}

}

Here is the image result using the Timer.util

Timer t  = new Timer();
    t.schedule(new runnableMethods(), 0,500);

import java.util.TimerTask;


public class runnableMethods extends TimerTask{

@Override
public void run() {

    SubPanel1.checkOfflineOnline();
}
}

Answer 1

Don't use java.util.Timer's on the Swing event dispatch thread, the EDT, as it is not thread safe for use with Swing. Either use the javax.swing.Timer or if you must use the java.util.Timer, use it on a background thread, and make sure that you make Swing calls only on the EDT. A SwingWorker would work well for this.