the public GUI gives me an invalid method declaration return type required [closed]

public class Main {

    public  GUI () {
        JFrameframe = new JFrame();
        JButton button = new JButton("click here!");

        JPanel panel = new JPanel();
        panel.setBoder(BorderFactory.createEmptyBoarder(30,30,10,30));
        panel.setLayout(new GridLayout(0,1));
        panel.add(button);


                

        frame.add(panel,BorderLayout.CENTER);
        frame.setdefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setTitle("first program");
        frame.pack();
        frame.setVisible(true);}}

the public GUI error what should I do ? it gives me invalid method declaration return type required, this is the first time I used GUI

Answer

Add a return type

public void  GUI () {
                JFrameframe = new JFrame();
                JButton button = new JButton("click here!");



                
                JPanel panel = new JPanel();
                panel.setBoder(BorderFactory.createEmptyBoarder(30,30,10,30));
                panel.setLayout(new GridLayout(0,1));
                panel.add(button);


                

            frame.add(panel,BorderLayout.CENTER);
            frame.setdefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.setTitle("first program");
            frame.pack();
            frame.setVisible(true);
}