Merge remote-tracking branch 'origin/main'

w4/Circle.java

@@ -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;
+    }
+}

w4/Main.java

@@ -0,0 +1,13 @@
+public class Main {
+    public static void main(String[] args) {
+        // 创建不同图形
+        Shape circle = new Circle(5);
+        Shape rectangle = new Rectangle(4, 6);
+        Shape triangle = new Triangle(3, 4);
+
+        // 统一打印面积
+        ShapeUtil.printArea(circle);
+        ShapeUtil.printArea(rectangle);
+        ShapeUtil.printArea(triangle);
+    }
+}

w4/Rectangle.java

@@ -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;
+    }
+}

w4/Shape.java

@@ -0,0 +1,4 @@
+public abstract class Shape {
+    // 计算面积的抽象方法
+    public abstract double getArea();
+}

w4/ShapeUtil.java

@@ -0,0 +1,6 @@
+public class ShapeUtil {
+    // 统一打印任意图形的面积
+    public static void printArea(Shape shape) {
+        System.out.println("图形面积 = " + shape.getArea());
+    }
+}

w4/Triangle.java

@@ -0,0 +1,14 @@
+public 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;
+    }
+}