diff --git a/java b/java
new file mode 100644
index 0000000..53b4594
--- /dev/null
+++ b/java
@@ -0,0 +1,48 @@
+Animal.java:
+public abstract class Animal {
+    public abstract void makeSound();
+}
+Dog.java:
+public class Dog extends Animal implements Swimmable {
+    @Override
+    public void makeSound() {
+        System.out.println("汪汪汪！");
+    }
+
+    @Override
+    public void swim() {
+        System.out.println("狗在游泳！");
+    }
+}
+Cat.java:
+public class Cat extends Animal {
+    @Override
+    public void makeSound() {
+        System.out.println("喵喵喵！");
+    }
+}
+Main.java:
+public class Main {
+    public static void main(String[] args) {
+        // 多态调用
+        Animal dog = new Dog();
+        Animal cat = new Cat();
+
+        System.out.println("狗的叫声：");
+        dog.makeSound();
+
+        System.out.println("猫的叫声：");
+        cat.makeSound();
+
+        // 测试游泳功能
+        if (dog instanceof Swimmable) {
+            ((Swimmable) dog).swim();
+        }
+
+        if (cat instanceof Swimmable) {
+            ((Swimmable) cat).swim();
+        } else {
+            System.out.println("猫不会游泳！");
+        }
+    }
+}
\ No newline at end of file