java/w5/ShapeTest.java

// 抽象父类 Shape
 abstract class Shape {
     // 抽象方法，由子类实现
     public abstract void draw();
 }
 // 子类 Circle
 class Circle extends Shape {
     @Override
     public void draw() {
         System.out.println("绘制圆形");
     }
 }
 // 子类 Rectangle
 class Rectangle extends Shape {
     @Override
     public void draw() {
         System.out.println("绘制矩形");
     }
 }
 // 工具类/主类
 public class ShapeTest {
     // 统一绘制方法，利用多态
     public static void drawShape(Shape s) {
         s.draw(); // 动态绑定，自动调用对应子类的draw()
     }
     public static void main(String[] args) {
         // 测试多态
         Shape circle = new Circle();
         Shape rectangle = new Rectangle();
         drawShape(circle);    // 输出：绘制圆形
         drawShape(rectangle); // 输出：绘制矩形
     }
 }