Código Java 100% correto

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

public class Inter {

private JFrame frame;
private JButton botao;

private void Inter(){
   frame = new JFrame();
   frame.setTitle("Exemplo de Layout");
   frame.setSize(200,200);
   frame.setLocation(500, 260);
   frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

   Container ct = frame.getContentPane();
   ct.setLayout(null);

   botao = new JButton("OK");
   botao.setBounds(50,10,150,25); // objeto.setBounds(esquerda, topo, largura, altura)
   ct.add(botao);

   Image Icone = Toolkit.getDefaultToolkit().getImage("icone.gif");

   frame.setIconImage(Icone);

   frame.setVisible(true);

   botao.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
         JOptionPane.showMessageDialog(null, "Bem Vindo!");
   }});

   frame.addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
         System.exit(0);
   }});

}

public static void main(String[] args) {
   Inter jx = new Inter();
   jx.Inter();
}

}