diff --git a/w5/ShapeTest.java b/w5/ShapeTest.java
new file mode 100644
index 0000000..091e5c5
--- /dev/null
+++ b/w5/ShapeTest.java
@@ -0,0 +1,35 @@
+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);
+    }
+}
\ No newline at end of file
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 12.58.43.png b/w5/截屏2026-04-06 12.58.43.png
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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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