simple progress bar in java swing

package application1;
import java.awt.HeadlessException;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class Application1 extends JFrame  implements ActionListener
{
JProgressBar jp;
JButton b;
 int i=5;
    public Application1()
    {
        jp=new JProgressBar();
        jp.setStringPainted(true);
        jp.setMinimum(0);
        jp.setMaximum(100);
        add(jp);
      jp.setBounds(30,40, 100,100);
        setLayout(null);
   b=new JButton("click to start");
   add(b);
   b.setBounds(40, 180, 180,80);
       b.addActionListener(this);
       //JOptionPane.showMessageDialog(null, "loading completed");
    }

    @Override
    public void actionPerformed(ActionEvent e)
    {
      
        i=i+5;
        jp.setValue(i);
        int t=jp.getValue();
        if(t==100)
        {
            JOptionPane.showMessageDialog(this, "loading completed");
        }
//     for(int i=0;i<=100;i++)
//     {
//         jp.setValue(i);
//     }
    }
   
    public static void main(String[] args)
    {
        Application1 a=new Application1();
        a.setVisible(true);
        a.setSize(500, 500);
        a.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
       
    }
}