问刷新JScrollPane

EN

import javax.swing.JTextArea;
import javax.swing.JScrollPane;
import javax.swing.JPanel;
import javax.swing.JFrame;

public class ScrollEx extends JFrame{
    private static final long serialVersionUID = 1L;

    private JPanel panel = new JPanel();
    private JTextArea area = new JTextArea(15, 20);
    private JScrollPane scroll = new JScrollPane(area);

    public ScrollEx(){
        super("JScrollPane Test!");

        setSize(300, 300);
        setDefaultCloseOperation(EXIT_ON_CLOSE);

        this.panel.setSize(300, 300);
        this.panel.add(scroll);

        for(Integer i = 0; i <= 50; i++){
            this.area.append(i.toString() + "\n");
        }

        getContentPane().add(panel);    

        setVisible(true);
    }

    public static void main(String [] args){
        new ScrollEx();
    }
}