diff --git a/4.1.txt b/4.1.txt
new file mode 100644
index 0000000..06d7405
Binary files /dev/null and b/4.1.txt differ
diff --git a/public class Circle extends Shape {.txt b/public class Circle extends Shape {.txt
new file mode 100644
index 0000000..584068d
--- /dev/null
+++ b/public class Circle extends Shape {.txt	
@@ -0,0 +1,12 @@
+public class Circle extends Shape {
+    private double radius;
+
+    public Circle(double radius) {
+        this.radius = radius;
+    }
+
+    @Override
+    public double getArea() {
+        return Math.PI * radius * radius;
+    }
+}
\ No newline at end of file
diff --git a/public class Rectangle extends Shap.txt b/public class Rectangle extends Shap.txt
new file mode 100644
index 0000000..90cb267
--- /dev/null
+++ b/public class Rectangle extends Shap.txt	
@@ -0,0 +1,14 @@
+public 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;
+    }
+}
\ No newline at end of file
diff --git a/public class ShapeUtil {.txt b/public class ShapeUtil {.txt
new file mode 100644
index 0000000..cf3fe54
--- /dev/null
+++ b/public class ShapeUtil {.txt	
@@ -0,0 +1,5 @@
+public class ShapeUtil {
+    public static void printArea(Shape shape) {
+        System.out.println("图形面积 = " + shape.getArea());
+    }
+}
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diff --git a/public class Test {.txt b/public class Test {.txt
new file mode 100644
index 0000000..d43e8ff
--- /dev/null
+++ b/public class Test {.txt	
@@ -0,0 +1,11 @@
+public class Test {
+    public static void main(String[] args) {
+        Shape circle = new Circle(2);
+        Shape rectangle = new Rectangle(3, 4);
+        Shape triangle = new Triangle(4, 5);
+
+        ShapeUtil.printArea(circle);
+        ShapeUtil.printArea(rectangle);
+        ShapeUtil.printArea(triangle);
+    }
+}
\ No newline at end of file