diff --git a/w5/AI协助记录 b/w5/AI协助记录
new file mode 100644
index 0000000..b3318df
--- /dev/null
+++ b/w5/AI协助记录
@@ -0,0 +1,4 @@
+· 帮我理清了多态中“编译看左边，运行看右边”的底层机制
+· 解释了为什么父类引用调用子类重写方法时会执行子类逻辑
+· 讲解了Java中public类与文件名的强制对应关系
+· 说明了单文件编写时非public类的正确写法
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diff --git a/w5/Pair.java b/w5/Pair.java
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--- /dev/null
+++ b/w5/Pair.java
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+public class Pair<K, V> {
+    private K key;
+    private V value;
+
+    public Pair(K key, V value) {
+        this.key = key;
+        this.value = value;
+    }
+
+    public K getKey() { return key; }
+    public void setKey(K key) { this.key = key; }
+    public V getValue() { return value; }
+    public void setValue(V value) { this.value = value; }
+
+    // 交换键值的静态方法
+    public static <K, V> Pair<V, K> swap(Pair<K, V> pair) {
+        return new Pair<>(pair.getValue(), pair.getKey());
+    }
+
+    @Override
+    public String toString() {
+        return "Pair{" + "key=" + key + ", value=" + value + '}';
+    }
+
+    public static void main(String[] args) {
+        // 测试
+        Pair<String, Integer> pair = new Pair<>("age", 18);
+        System.out.println("交换前：" + pair);
+
+        Pair<Integer, String> swappedPair = Pair.swap(pair);
+        System.out.println("交换后：" + swappedPair);
+    }
+}
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diff --git a/w5/ShapeTest.java b/w5/ShapeTest.java
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+++ b/w5/ShapeTest.java
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+class Shape {
+    public void draw() {
+        System.out.println("绘制一个形状");
+    }
+}
+
+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");
+    }
+}
+
+public class ShapeTest {
+    public static void drawShape(Shape s) {
+        s.draw();
+    }
+
+    public static void main(String[] args) {
+        Shape shape1 = new Circle();
+        Shape shape2 = new Rectangle();
+        Shape shape3 = new Shape();
+
+        drawShape(shape1);
+        drawShape(shape2);
+        drawShape(shape3);
+    }
+}
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diff --git a/w5/USBTest.java b/w5/USBTest.java
new file mode 100644
index 0000000..5a655e9
--- /dev/null
+++ b/w5/USBTest.java
@@ -0,0 +1,55 @@
+// 接口
+interface USB {
+    void open();
+    void close();
+}
+
+// Mouse类实现USB接口
+class Mouse implements USB {
+    @Override
+    public void open() {
+        System.out.println("鼠标已连接，可以移动光标");
+    }
+
+    @Override
+    public void close() {
+        System.out.println("鼠标已断开");
+    }
+}
+
+// Keyboard类实现USB接口
+class Keyboard implements USB {
+    @Override
+    public void open() {
+        System.out.println("键盘已连接，可以输入文字");
+    }
+
+    @Override
+    public void close() {
+        System.out.println("键盘已断开");
+    }
+}
+
+// Computer类
+class Computer {
+    public void useUSB(USB device) {
+        System.out.println(">>> 正在接入设备...");
+        device.open();
+        System.out.println("<<< 正在拔出设备...");
+        device.close();
+        System.out.println();
+    }
+}
+
+// 主类（文件名必须是 USBTest.java）
+public class USBTest {
+    public static void main(String[] args) {
+        Computer computer = new Computer();
+        
+        USB mouse = new Mouse();
+        USB keyboard = new Keyboard();
+        
+        computer.useUSB(mouse);
+        computer.useUSB(keyboard);
+    }
+}
diff --git a/w5/截屏2026-04-06 13.01.27.png b/w5/截屏2026-04-06 13.01.27.png
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