From ba1ca63b82d51b9ab3639c1bfe2afd21f0c0ee9a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=8C=83=E9=A6=A8=E9=81=A5?= <3603458499qq.com>
Date: Tue, 23 Jun 2026 17:12:21 +0800
Subject: [PATCH] Add w6 folder with animal sound system

---
 w6/Animal.java    |  3 +++
 w6/Cat.java       |  6 ++++++
 w6/Dog.java       | 11 +++++++++++
 w6/Main.java      | 23 +++++++++++++++++++++++
 w6/Swimmable.java |  3 +++
 5 files changed, 46 insertions(+)
 create mode 100644 w6/Animal.java
 create mode 100644 w6/Cat.java
 create mode 100644 w6/Dog.java
 create mode 100644 w6/Main.java
 create mode 100644 w6/Swimmable.java

diff --git a/w6/Animal.java b/w6/Animal.java
new file mode 100644
index 0000000..b07d6fa
--- /dev/null
+++ b/w6/Animal.java
@@ -0,0 +1,3 @@
+public abstract class Animal {
+    public abstract void makeSound();
+}
\ No newline at end of file
diff --git a/w6/Cat.java b/w6/Cat.java
new file mode 100644
index 0000000..5a0c4b4
--- /dev/null
+++ b/w6/Cat.java
@@ -0,0 +1,6 @@
+public class Cat extends Animal {
+    @Override
+    public void makeSound() {
+        System.out.println("Meow!");
+    }
+}
\ No newline at end of file
diff --git a/w6/Dog.java b/w6/Dog.java
new file mode 100644
index 0000000..4880968
--- /dev/null
+++ b/w6/Dog.java
@@ -0,0 +1,11 @@
+public class Dog extends Animal implements Swimmable {
+    @Override
+    public void makeSound() {
+        System.out.println("Woof!");
+    }
+
+    @Override
+    public void swim() {
+        System.out.println("Dog is swimming");
+    }
+}
\ No newline at end of file
diff --git a/w6/Main.java b/w6/Main.java
new file mode 100644
index 0000000..02315e3
--- /dev/null
+++ b/w6/Main.java
@@ -0,0 +1,23 @@
+public class Main {
+    public static void main(String[] args) {
+        // Test polymorphism with Animal references
+        Animal dog = new Dog();
+        Animal cat = new Cat();
+
+        System.out.println("Testing makeSound():");
+        dog.makeSound(); // Should output "Woof!"
+        cat.makeSound(); // Should output "Meow!"
+
+        // Test swim() method for Dog
+        System.out.println("\nTesting swim():");
+        if (dog instanceof Swimmable) {
+            Swimmable swimmableDog = (Swimmable) dog;
+            swimmableDog.swim(); // Should output "Dog is swimming"
+        }
+
+        // Test that Cat doesn't implement Swimmable
+        if (!(cat instanceof Swimmable)) {
+            System.out.println("Cat cannot swim");
+        }
+    }
+}
\ No newline at end of file
diff --git a/w6/Swimmable.java b/w6/Swimmable.java
new file mode 100644
index 0000000..b7a501e
--- /dev/null
+++ b/w6/Swimmable.java
@@ -0,0 +1,3 @@
+public interface Swimmable {
+    void swim();
+}
\ No newline at end of file