import java.awt.FlowLayout;

import javax.swing.JButton;
import javax.swing.JFrame;

public class SecondGUI extends JFrame {
    public static void main(String[] args) {
        // new SecondGUI().setVisible(true);
        new SecondGUI();
    }
    public SecondGUI(){
        super("SecondGUI");
        getContentPane().setLayout(new FlowLayout());
        getContentPane().add(new JButton("B1"));
        getContentPane().add(new JButton("B2"));
        getContentPane().add(new JButton("B3"));
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        pack();
        setVisible(true);
    }
}