diff --git a/w4/ShapeAreaCalculator.java b/w4/ShapeAreaCalculator.java
new file mode 100644
index 0000000..6fd8dd3
--- /dev/null
+++ b/w4/ShapeAreaCalculator.java
@@ -0,0 +1,72 @@
+package src.main.w5;
+abstract class Shape {
+    public abstract double getArea();
+}
+
+class Circle extends Shape {
+    private double radius;
+
+    public Circle(double radius) {
+        this.radius = radius;
+    }
+
+    @Override
+    public double getArea() {
+        return Math.PI * radius * radius;
+    }
+}
+class Rectangle extends Shape {
+    private double width;
+    private double height;
+
+    public Rectangle(double width, double height) {
+        this.width = width;
+        this.height = height;
+    }
+
+    @Override
+    public double getArea() {
+        return width * height;
+    }
+}
+
+class Triangle extends Shape {
+    private double base;
+    private double height;
+
+    public Triangle(double base, double height) {
+        this.base = base;
+        this.height = height;
+    }
+
+    @Override
+    public double getArea() {
+        return 0.5 * base * height;
+    }
+}
+
+class ShapeUtil {
+    public static void printArea(Shape shape) {
+        System.out.printf("该图形的面积为：%.2f%n", shape.getArea());
+    }
+}
+
+public class ShapeAreaCalculator {
+    public static void main(String[] args) {
+        Shape circle = new Circle(2.0);
+        Shape rectangle = new Rectangle(3.0, 4.0);
+        Shape triangle = new Triangle(3.0, 4.0);
+
+        System.out.println("圆形：");
+        ShapeUtil.printArea(circle);
+
+        System.out.println("矩形：");
+        ShapeUtil.printArea(rectangle);
+
+        System.out.println("三角形：");
+        ShapeUtil.printArea(triangle);
+    }
+}
+
+
+