create a simple java Application program that shows the use of FlowLayout that takes no parameter to arrange the component at the center of the window

import java.awt.*;
import javax.swing.*;

public class FltNoParameter extends JFrame{

    public FltNoParameter(){
        setLayout(new FlowLayout());
        for(int i=1;i<5;i++)
        add(new JButton(" "+i));
        setSize(500,300);
        setVisible(true);
    }
    public static void main(String args[])
    {
        FltNoParameter bt = new FltNoParameter();
        bt.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE );
    }

}