[GUI]

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

public class HelloSwing {
	public static void main (String[] args) {
		JFrame f= new JFrame ("Hello");
		JPanel p = new JPanel();
		JButton b = new JButton("Press Me");
		
		f.setSize(400,400);
		f.setContentPane(p);
		p.add(b);//판넬에 버튼을 추가
		
		f.setVisible(true);
	}

}

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

public class JComponentExample {

	class MyJComponent extends JComponent{
		public void paint (Graphics g) {
			g.setColor(Color.green);
			g.fillOval(50,10,150,150);
		}
	}
	
	public static void main(String[] argument) {
		
		MyJComponent com = new MyJComponent();
	
		JFrame.setDefaultLookAndFeelDecorated(true);
		JFrame frame = new JFrame("JComponent Example");
		frame.setSize(300,200);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	
		frame.add(com);
		frame.setVisible(true);
}

}