11月9日——第一课Java（浙大）

1、public class Picture extends JFrame {
private static final long serialVersionUID = 1L;
private int width;
private int height;

private ArrayList<Shape> listShape = new ArrayList<Shape>();？？？private class ShapesPanel extends JPanel {？？？在公有类中定义一个私有类？    private static final long serialVersionUID = 1L;    @Override    protected void paintComponent(Graphics g) {        super.paintComponent(g);        for ( Shape s : listShape )        {            s.draw(g);        }               }}