package Sum;
import java.util.*;
class Rect {
double length;
double width;
double perimeter;
double area; //长宽面积周长成员变量
Rect(double n, double k) {
length = n;
width = k;
} //构造方法 将值赋给成员变量
double area1() {
area = length * width;
return area;
} //计算返回面积
double perimeter1() {
perimeter = 2 * (length + width);
return perimeter;
} //计算返回周长
}
public class Rectangle {
public static void main(String[] args) {
// TODO Auto-generated method stub
System.out.println("请输入矩形的长和宽:");
Scanner reader = new Scanner(System.in);
double num1 = reader.nextDouble();
double num2 = reader.nextDouble();
Rect a = new Rect(num1, num2); //创建对象
System.out.println("矩形的面积为:" + a.area1());
System.out.println("矩形的周长为:" + a.perimeter1());
}
}
![](https://img2018.cnblogs.com/blog/1797076/201909/1797076-20190918182220373-2105785178.png)