0117 面向对象OOP有关方法、类、构造方法及权限修饰符的练习

public class juxing {
//编写一个矩形类，将长与宽作为矩形类的属性，在构造方法中将长、宽初始化，定义一个成员方法求此矩形面积
 
    int chang;
 
    int kuan;
 
    int mianji;
 
    double s;
 
    double c;
 
    int n = 4;
 
    String tuxing = "矩形";
 
    void xingzhuang(){  //无返回无参数
 
        tuxing = "矩形";
 
    }
 
   void djx(double m){     //无返回值，有参数  ？？？？
 
        m = c-2;
       System.out.println("对角线 = " + m);
    }
 
    double mianji(int chang,int kuan){  //有返回值，有参数
 
        return mianji= chang*kuan;
    }
 
    boolean bianshu(){        //有返回值，无参数
        boolean b = true;
 
        if (n == 4){
            System.out.println("有四条边 " + b);
        }else{
            System.out.println("不是四边形");
        }
        return b;
    }
 
        public static void main (String[] args){
 
            juxing jx = new juxing();
 
        jx.chang = 10;
 
        jx.kuan = 5;
 
        jx.s = jx.chang*jx.kuan;
 
        jx.mianji = jx.chang * jx.kuan;
 
        jx.c = 2 * (jx.chang + jx.kuan);
 
        jx.djx(jx.c);
 
        System.out.println("图形："+jx.tuxing);
 
        System.out.println("面积= "+jx.s);
 
        System.out.println("矩形的面积= "+jx.mianji);
 
        System.out.println("周长 = "+jx.c);
 
        //System.out.println("对角线 = "+jx.m);
 
        if (jx.bianshu()){
            System.out.println("这个图形是四边形");
        }else{
            System.out.println("这个图形不是四边形");
        }
 
    }
 
}