为啥我的面板颜色没变化啊！

[BUG的缔造者]

import java.awt.Color;
import java.awt.Container;

import javax.swing.JButton;
import javax.swing.JFrame;

public class MyWindow {
	public static MyWindowDemo mw1;
	public static MyWindowDemo mw2;
	public static void main(String[] args) {
		JButton butt1=new JButton("我是第一个按钮");
		String name1="我的第一个窗口";
		String name2="我的第二个窗口";
		mw1=new MyWindowDemo(name1,butt1,Color.BLACK,350,450);
		mw1.setVisible(true);
		JButton butt2=new JButton("我是第二个按钮");
		mw2=new MyWindowDemo(name2,butt2,Color.blue,300,450);
		mw2.setVisible(true);
	}

}
class MyWindowDemo extends JFrame{
	public MyWindowDemo(String name,JButton button,Color c,int w,int h){
		super();
		setTitle(name);setSize(w,h);
		Container contentPane=getContentPane();
		contentPane.add(button);
		contentPane.setBackground(c);
	}
}

[BUG的缔造者]

还是不行啊.....

[自由自在_Yu]

public MyWindowDemo(String name,JButton button,Color c,int w,int h){
        super();
        setTitle(name);setSize(w,h);
        Container contentPane=getContentPane();
        contentPane.add(button);
        setBackground(c);
    }