七周

public class Demo1 {
    double length;
    double width;

    public void getArea() {
        System.out.println(length * width);
    }

    public void getPer() {
        System.out.println((length + width) * 2);
    }

    public void showAll() {
        System.out.println("长是" + length);
        System.out.println("宽是" + width);
        System.out.println("面积是");
        getArea();
        System.out.println("周长是");
        getPer();
    }

}

import java.util.*;

public class Demo1 {

    public static void main(String[] args) {
        Rectangle p1 = new Rectangle();
        Scanner input = new Scanner(System.in);
        System.out.println("请输入长");
        p1.length = input.nextInt();
        System.out.print("请输入宽");
        p1.width = input.nextInt();
        p1.showAll();

    }

}