package w5; public abstract class Shape { public abstract void draw(); } class Circle extends Shape { @Override public void draw() { System.out.println("绘制一个圆形"); } } class Rectangle extends Shape { @Override public void draw() { System.out.println("绘制一个矩形"); } } class ShapeTest { public static void drawShape(Shape s) { s.draw(); } public static void main(String[] args) { Shape circle = new Circle(); Shape rectangle = new Rectangle(); drawShape(circle); drawShape(rectangle); } }