Java swing help!

[boburob]

Hey everyone, im writing a blackjack program with java swing and im having problems with setting the layout with panels and frames.

I want to apply a different layout to two different panels, add them to a frame and then display the frame, heres my code:

//Blackjack
//By Thomas Bean

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

public class blackjack extends JFrame {
	//create icons used in toolbar
	//hearts
	ImageIcon two_hearts = new ImageIcon("image/51.png");
	ImageIcon three_hearts = new ImageIcon("image/47.png");
	ImageIcon four_hearts = new ImageIcon("image/43.png");
	ImageIcon five_hearts = new ImageIcon("image/39.png");
	ImageIcon six_hearts = new ImageIcon("image/35.png");
	ImageIcon seven_hearts = new ImageIcon("image/31.png");
	ImageIcon eight_hearts = new ImageIcon("image/27.png");
	ImageIcon nine_hearts = new ImageIcon("image/23.png");
	ImageIcon ten_hearts = new ImageIcon("image/19.png");
	ImageIcon jack_hearts = new ImageIcon("image/15.png");
	ImageIcon queen_hearts = new ImageIcon("image/11.png");
	ImageIcon king_hearts = new ImageIcon("image/7.png");
	ImageIcon ace_hearts = new ImageIcon("image/3.png");
	//clubs
	ImageIcon two_clubs = new ImageIcon("image/49.png");
	ImageIcon three_clubs = new ImageIcon("image/45.png");
	ImageIcon four_clubs = new ImageIcon("image/41.png");
	ImageIcon five_clubs = new ImageIcon("image/37.png");
	ImageIcon six_clubs = new ImageIcon("image/33.png");
	ImageIcon seven_clubs = new ImageIcon("image/29.png");
	ImageIcon eight_clubs = new ImageIcon("image/25.png");
	ImageIcon nine_clubs = new ImageIcon("image/21.png");
	ImageIcon ten_clubs = new ImageIcon("image/17.png");
	ImageIcon jack_clubs = new ImageIcon("image/13.png");
	ImageIcon queen_clubs = new ImageIcon("image/9.png");
	ImageIcon king_clubs = new ImageIcon("image/5.png");
	ImageIcon ace_clubs = new ImageIcon("image/1.png");
	//spades
	ImageIcon two_spades = new ImageIcon("image/50.png");
	ImageIcon three_spades = new ImageIcon("image/46.png");
	ImageIcon four_spades = new ImageIcon("image/42.png");
	ImageIcon five_spades = new ImageIcon("image/38.png");
	ImageIcon six_spades = new ImageIcon("image/34.png");
	ImageIcon seven_spades = new ImageIcon("image/30.png");
	ImageIcon eight_spades = new ImageIcon("image/26.png");
	ImageIcon nine_spades = new ImageIcon("image/22.png");
	ImageIcon ten_spades = new ImageIcon("image/18.png");
	ImageIcon jack_spades = new ImageIcon("image/14.png");
	ImageIcon queen_spades = new ImageIcon("image/10.png");
	ImageIcon king_spades = new ImageIcon("image/6.png");
	ImageIcon ace_spades = new ImageIcon("image/2.png");
	//diamonds
	ImageIcon two_diamonds = new ImageIcon("image/52.png");
	ImageIcon three_diamonds = new ImageIcon("image/48.png");
	ImageIcon four_diamonds = new ImageIcon("image/44.png");
	ImageIcon five_diamonds = new ImageIcon("image/40.png");
	ImageIcon six_diamonds = new ImageIcon("image/36.png");
	ImageIcon seven_diamonds = new ImageIcon("image/32.png");
	ImageIcon eight_diamonds = new ImageIcon("image/28.png");
	ImageIcon nine_diamonds = new ImageIcon("image/24.png");
	ImageIcon ten_diamonds = new ImageIcon("image/20.png");
	ImageIcon jack_diamonds = new ImageIcon("image/16.png");
	ImageIcon queen_diamonds = new ImageIcon("image/12.png");
	ImageIcon king_diamonds = new ImageIcon("image/8.png");
	ImageIcon ace_diamonds = new ImageIcon("image/4.png");
	//card tops
	ImageIcon cardIcon = new ImageIcon("image/b1fv.png");
	ImageIcon pc_cardIcon = new ImageIcon("image/b2fv.png");
	//
	//create buttons
	JButton cardOne = new JButton("", cardIcon);
	JButton cardTwo = new JButton("", cardIcon);
	JButton pc_cardOne = new JButton("", pc_cardIcon);
	JButton pc_cardTwo = new JButton("", pc_cardIcon);
	JButton new_game = new JButton("New Game");
	//
	//constructor
	public blackjack() {
		super("Blackjack");
		setSize(600, 400);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		GridLayout cards = new GridLayout(1, 2, 10, 10);
		JPanel panel = new JPanel();
		JPanel panel2 = new JPanel();
		panel.setLayout(cards);
		panel2.setLayout(cards);
		JFrame frame = new JFrame();
		panel.add(cardOne);
		panel.add(cardTwo);
		panel2.add(pc_cardOne);
		panel2.add(pc_cardTwo);
		frame.add(panel);
		frame.add(panel2);
                add(frame);
		setVisible(true);
	}



	//main function
	public static void main(String[] arguments) {
		blackjack main = new blackjack();
	}
}

This gives me these errors when run:

thomas@thomas-laptop:~/Documents/Work/Programming/Blackjack$ java blackjackException in thread "main" java.lang.IllegalArgumentException: adding a window to a container
	at java.awt.Container.addImpl(Container.java:1061)
	at java.awt.Container.add(Container.java:974)
	at javax.swing.JFrame.addImpl(JFrame.java:562)
	at java.awt.Container.add(Container.java:377)
	at blackjack.<init>(blackjack.java:95)
	at blackjack.main(blackjack.java:103)

Thank you for any help!