添加 'w6'

w6

@@ -0,0 +1,80 @@
+// 抽象类 Animal
+abstract class Animal {
+    protected String name;
+    
+    public Animal(String name) {
+        this.name = name;
+    }
+    
+    public abstract void makeSound();
+}
+
+// 接口 Swimmable
+interface Swimmable {
+    void swim();
+}
+
+// Dog 类：继承 Animal，实现 Swimmable
+class Dog extends Animal implements Swimmable {
+    public Dog(String name) {
+        super(name);
+    }
+    
+    @Override
+    public void makeSound() {
+        System.out.println(name + " 汪汪叫");
+    }
+    
+    @Override
+    public void swim() {
+        System.out.println(name + " 正在游泳 ");
+    }
+}
+
+// Cat 类：只继承 Animal，不实现 Swimmable
+class Cat extends Animal {
+    public Cat(String name) {
+        super(name);
+    }
+    
+    @Override
+    public void makeSound() {
+        System.out.println(name + " 喵喵叫");
+    }
+}
+
+// 测试主类
+public class AnimalTest {
+    public static void main(String[] args) {
+        // 多态测试
+        Animal dog = new Dog("旺财");
+        Animal cat = new Cat("咪咪");
+        
+        System.out.println("=== 动物叫声 ===");
+        dog.makeSound();
+        cat.makeSound();
+        
+        System.out.println("\n=== 游泳测试 ===");
+        // 只有实现 Swimmable 的动物才能游泳
+        if (dog instanceof Swimmable) {
+            ((Swimmable) dog).swim();
+        }
+        
+        if (cat instanceof Swimmable) {
+            ((Swimmable) cat).swim();
+        } else {
+            System.out.println(cat.name + " 不会游泳 ");
+        }
+        
+        System.out.println("\n=== 集合多态测试 ===");
+        // 将所有动物放入数组
+        Animal[] animals = {dog, cat};
+        for (Animal animal : animals) {
+            animal.makeSound();
+            // 检查是否会游泳
+            if (animal instanceof Swimmable) {
+                ((Swimmable) animal).swim();
+            }
+        }
+    }
+}