53 lines
1.7 KiB
Java
53 lines
1.7 KiB
Java
package chapter4.demo45;
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/**
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* 图形计算器类
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* 1. final 类：防止被继承
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* 2. 私有构造函数（不可被实例化）
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* 只有静态方法，不需要实例化，所有方法都可以通过类名调用
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*/
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public final class ShapeCalculate {
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private ShapeCalculate() {
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throw new AssertionError("不应该被实例化");
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}
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// 打印图形面积
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public static void printArea(Shape shape) {
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if (shape instanceof Rectangle) {
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System.out.println("正方形面积："+shape.getArea());
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} else if (shape instanceof Circle) {
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System.out.println("圆形面积："+shape.getArea());
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} else {
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System.out.println("未知图形面积：" + shape.getArea());
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}
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}
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// 打印图形周长
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// public static void printPerimeter(Shape shape) {
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// if (shape instanceof Rectangle) {
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// System.out.print("长方形");
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// } else if (shape instanceof Circle) {
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// System.out.print("圆形");
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// } else {
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// System.out.print("未知图形");
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// }
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// System.out.println("周长："+shape.getPerimeter());
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// }
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public static void printPerimeter(Circle circle) {
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System.out.println("圆形周长："+circle.getPerimeter());
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}
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public static void printPerimeter(Rectangle rectangle) {
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System.out.println("长方形周长："+rectangle.getPerimeter());
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}
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// 打印计算器菜单
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public static void printMenu() {
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System.out.println("==========图形计算器==========");
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System.out.println("1.圆形");
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System.out.println("2.长方形");
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System.out.print("请输入序号选择功能：");
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}
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}
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