import javax.swing.JFrame;public class PanelDemo {public static void main(String[] args) { JFrame frm=new JFrame("我的第一個框架!"); frm.setSize(300,300); frm.setLocationRelativeTo(null); JPanel myPane=new JPanel(); frm.setContentPane(myPane); myPane.setBackground(Color.BLUE); frm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frm.setVisible(true);}}