删除 'W4'

W4

@@ -1,57 +0,0 @@
-// 抽象图形类
-abstract class Shape {
-    public abstract double getArea();
-}
-
-// 圆形
-class Circle extends Shape {
-    private double r;
-
-    public Circle(double r) {
-        this.r = r;
-    }
-
-    @Override
-    public double getArea() {
-        return Math.PI * r * r;
-    }
-}
-
-// 矩形
-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;
-    }
-}
-
-// 三角形
-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;
-    }
-}
-
-// 工具类
-class ShapeUtil {
-    public static void printArea(Shape shape) {
-        System.out.println("面积：" + shape.getArea());
-    }
-}