Première fenêtre en Java

import java.awt.Color;

import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class FenetreComboBox extends JFrame {
	private JComboBox<String> txtTypeclient = new JComboBox<String>(new String[] {"Public", "Privé", "Divers"});
	public FenetreComboBox(){
		this.setTitle("Ma première fenêtre Java");
		this.setSize(400, 500);
		this.setLocationRelativeTo(null);
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);             
		this.setVisible(true);
		//Instanciation d'un objet JPanel
		JPanel pan = new JPanel();
		//Définition de sa couleur de fond
		pan.setBackground(Color.ORANGE);  
		pan.add(this.txtTypeclient);      
		//On prévient notre JFrame que notre JPanel sera son content pane
		this.setContentPane(pan);               
		this.setVisible(true);
	}
	public static void main(String[] args) {
		FenetreComboBox uneFenetreComboBox = new FenetreComboBox();
	}

}