public class Okno1 extends JFrame{
    private JButton next = new JButton("Next");
    private Panel1 Panel1 = new Panel1();
    
    public Okno1(String name){
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(320, 480);
        setVisible(true);
        setTitle(name);
        setLayout(new FlowLayout());
        
        add(next);
        //pack();
        
        next.addActionListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent e) {
                add(Panel1);
            }        
        });
    }
}