[Java]Problema di swing

[Luc@s]

Sto imparando le swing e mi sono scrotto questo cod:

 import java.*;
import javax.swing.*;

public class CPrinc extends JFrame {

	public static void main(String argv[]) {
		JFrame FPrinc = new JFrame("Prova di Java");
		JButton BEsci = new JButton("Esci");
		BEsci.setEnabled(true);
		BEsci.setBounds(10, 10, 200, 150);
		FPrinc.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		FPrinc.setVisible(true);
		FPrinc.setBounds(10, 10, 400, 300);
		FPrinc.add(BEsci);
		FPrinc.pack();
	}

}

Perche nn mi visualizza il button e Ginipad mi da

C:\sdk\bin\javaw.exe -ea  -classpath "C:\Documents and Settings\Admin\Desktop" CPrinc
java.lang.Error: Do not use javax.swing.JFrame.add() use javax.swing.JFrame.getContentPane().add() instead
	at javax.swing.JFrame.createRootPaneException(JFrame.java:446)
	at javax.swing.JFrame.addImpl(JFrame.java:472)
	at java.awt.Container.add(Container.java:298)
	at CPrinc.main(CPrinc.java:14)
Exception in thread "main" 
Process CPrinc terminated.

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