package gg;//包名

public class Circle {
	private double a;//聲明半徑變量，Circle類的一個屬性
	
	public Circle(){//構造
		
	}
	public Circle(double a){//構造方法Circle(double a)設置圓的半徑
		this.a=a;
	}
	public double getA() {//讀取圓的半徑
		return a;
	}
	public void setA(double a) {//設置圓的半徑
		this.a = a;
	}
	
	public double calculateArea(){//計算圓的面積并返回結果
		double area;
		area=Math.PI*a*a;
		return area;
	}
}