怎么做，求大神解答

（1）定義圖形接口IShape，包括1個接口方法GetArea()，返回值類型為double；
（2）定義圓形類Circle支持IShape。Circle成員包括：字段半徑r（數據為double）及其對應的讀寫函數，初始化半徑值的構造函數；隱式實現IShape接口方法的GetArea()方法，該方法的返回值為圓的面積。

慕數據0194010

2018-06-06

源自：Java入門第三季 1-1

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qq_焦良_0
2018-06-07

public?interface?IShape{
????double?GetArea();
}

public?class?Circle?implements?IShape{
????protected?double?r;
????protected?static?int?NumberCircle=0;
????public?Circle(){}????//無參構造函數
????
????public?Circle(double?r){
????????setR(r);
????}
????
????public?void?setR(double?r){
????????this.r=r;
????}
????
????public?double?getR(){
????????return?r;
????}
????
????public?double?GetArea(){
????????double?area?=?r*r*Math.PI;
????????NumberCircle++;
????????return?area;
????????
????}
}