【程式語言】JAVA的期末上機測驗｜物件導向程式設計題目(protected,extends,constructor,static function)

test.java

class Circle {
    protected int radius;
    protected static double pi; 
    Circle(){
        radius = 3;
        pi = 3.14;
    }
    static Circle bigger(Circle c1 ,Circle c2){
        if (c1.area() > c2.area()){
            return c1;
        }
        else {
            return c2;
        }
    }
    Circle(int r , double p){
        radius = r;
        pi = p;
    }

    double area() {
        return radius*radius*pi;
    }    
}

class Disk extends Circle {
    protected int price;
    Disk(){}
    Disk(int p , int r) {
        this.price = p;
        radius = r;
    }
    void show() {
        System.out.println("The price for thie disk is " + price + " with radius " + radius);
    }
}

public class test {
    public static void main(String[] args) {
        Circle c1 = new Circle();
        Circle c2 = new Circle(4,3.14);
        Disk d1 = new Disk(100,10);
        Circle b = Circle.bigger(c1,c2);
        Circle[] arr = new Circle[5];
        arr[0] = c1;arr[1] = c2;arr[2] = d1;
        arr[3] = new Circle(2,3.14); arr[4] = new Disk(150,12);
        System.out.println("Area for c1 is " + c1.area());
        System.out.println("Area for c2 is " + c2.area());
        System.out.println("The bigger one is " + b.area());
        d1.show();
        System.out.println("The total area:" + addArea(arr));
    }

    static Double addArea(Circle[] ar) {
        double sum = 0;
        for (int i = 0 ; i < ar.length ; i++) {
            sum += ar[i].area();
        }
        return sum;
    }
}

Result: