上传文件至 'w4'

w4/Circle.java

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+public class Circle extends Shape {
+    private double radius;
+    
+    // 构造方法
+    public Circle(double radius) {
+        this.radius = radius;
+    }
+    
+    // 实现抽象方法，计算圆的面积
+    @Override
+    public double getArea() {
+        return Math.PI * radius * radius;
+    }
+    
+    // getter和setter方法
+    public double getRadius() {
+        return radius;
+    }
+    
+    public void setRadius(double radius) {
+        this.radius = radius;
+    }
+}

w4/Rectangle.java

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+public class Rectangle extends Shape {
+    private double width;
+    private double height;
+    
+    // 构造方法
+    public Rectangle(double width, double height) {
+        this.width = width;
+        this.height = height;
+    }
+    
+    // 实现抽象方法，计算矩形的面积
+    @Override
+    public double getArea() {
+        return width * height;
+    }
+    
+    // getter和setter方法
+    public double getWidth() {
+        return width;
+    }
+    
+    public void setWidth(double width) {
+        this.width = width;
+    }
+    
+    public double getHeight() {
+        return height;
+    }
+    
+    public void setHeight(double height) {
+        this.height = height;
+    }
+}

w4/ShapeCalculator.java

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+// 抽象类 Shape
+abstract class Shape {
+    // 抽象方法，计算面积
+    public abstract double getArea();
+}
+
+// 工具类 ShapeUtil
+class ShapeUtil {
+    // 打印图形的面积
+    public static void printArea(Shape shape) {
+        System.out.println("图形的面积为：" + shape.getArea());
+    }
+}
+
+// 主类 Main
+public class ShapeCalculator {
+    public static void main(String[] args) {
+        // 创建不同的图形对象
+        Shape circle = new Circle(5.0);      // 半径为5的圆
+        Shape rectangle = new Rectangle(4.0, 6.0);  // 宽4、高6的矩形
+        Shape triangle = new Triangle(3.0, 8.0);    // 底3、高8的三角形
+        
+        // 使用ShapeUtil打印各图形的面积
+        System.out.println("圆的面积：");
+        ShapeUtil.printArea(circle);
+        
+        System.out.println("矩形的面积：");
+        ShapeUtil.printArea(rectangle);
+        
+        System.out.println("三角形的面积：");
+        ShapeUtil.printArea(triangle);
+    }
+}

w4/Triangle.java

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+public class Triangle extends Shape {
+    private double base;
+    private double height;
+    
+    // 构造方法
+    public Triangle(double base, double height) {
+        this.base = base;
+        this.height = height;
+    }
+    
+    // 实现抽象方法，计算三角形的面积
+    @Override
+    public double getArea() {
+        return 0.5 * base * height;
+    }
+    
+    // getter和setter方法
+    public double getBase() {
+        return base;
+    }
+    
+    public void setBase(double base) {
+        this.base = base;
+    }
+    
+    public double getHeight() {
+        return height;
+    }
+    
+    public void setHeight(double height) {
+        this.height = height;
+    }
+}