package com.study.demo2; public class Main { public static void main(String[] args) { Rectangle rect1 = new Rectangle(5.0, 3.0); System.out.println("面积:" + rect1.getArea()); System.out.println("周长:" + rect1.getPerimeter()); Rectangle rect2 = new Rectangle(); System.out.println("默认面积:" + rect2.getArea()); System.out.println("默认周长:" + rect2.getPerimeter()); rect2.setWidth(2.5); rect2.setHeight(4.0); System.out.println("修改后面积:" + rect2.getArea()); System.out.println("修改后周长:" + rect2.getPerimeter()); } }