diff --git a/w4/Circle.java b/w4/Circle.java
new file mode 100644
index 0000000..99982ad
--- /dev/null
+++ b/w4/Circle.java
@@ -0,0 +1,12 @@
+package shiyan2;
+
+public class Circle extends Shape {
+    private double radius;
+
+    public Circle(double radius) {
+        this.radius = radius;
+    }
+    public double getArea() {
+        return Math.PI * radius * radius;
+    }
+}
diff --git a/w4/Rectangle.java b/w4/Rectangle.java
new file mode 100644
index 0000000..5f78631
--- /dev/null
+++ b/w4/Rectangle.java
@@ -0,0 +1,10 @@
+package shiyan2;
+
+public class Rectangle extends Shape {
+    private double width, height;
+    public Rectangle(double width, double height) {
+        this.width = width;
+        this.height = height;
+    }
+    public double getArea() {return width*height;}
+}
diff --git a/w4/Shape.java b/w4/Shape.java
new file mode 100644
index 0000000..6e98c1a
--- /dev/null
+++ b/w4/Shape.java
@@ -0,0 +1,7 @@
+package shiyan2;
+
+
+public abstract class Shape {
+    public abstract double getArea();
+}
+
diff --git a/w4/ShapeUtil.java b/w4/ShapeUtil.java
new file mode 100644
index 0000000..85296d6
--- /dev/null
+++ b/w4/ShapeUtil.java
@@ -0,0 +1,8 @@
+package shiyan2;
+
+// ShapeUtil.java
+public class ShapeUtil {
+    public static void printArea(Shape shape) {
+        System.out.println("图形的面积为：" + shape.getArea());
+    }
+}
\ No newline at end of file
diff --git a/w4/Test.java b/w4/Test.java
new file mode 100644
index 0000000..3926d2e
--- /dev/null
+++ b/w4/Test.java
@@ -0,0 +1,14 @@
+package shiyan2;
+
+// Test.java
+public class Test {
+    public static void main(String[] args) {
+        Shape circle = new Circle(3);
+        Shape rectangle = new Rectangle(4, 5);
+        Shape triangle = new Triangle(6, 7);
+
+        ShapeUtil.printArea(circle);
+        ShapeUtil.printArea(rectangle);
+        ShapeUtil.printArea(triangle);
+    }
+}
\ No newline at end of file