class Circle{
    private double redius,area,lenth;
    public double getArea(){
        return Math.PI*redius*redius;
    }
    public double getLength(){
        return 2*Math.PI*redius;
    }
    public void setRedius(double redius){
        this.redius=redius;
    }
}
public class Try {
    public static void main(String[] args) {
        try{
            Class cu=Class.forName("Circle");
            Circle circle=(Circle)cu.newInstance();
            circle.setRedius(100);
            System.out.println("圆的面积为："+circle.getArea());
            System.out.println("圆的周长为："+circle.getLength());
        }
        catch(Exception e){
            System.out.println("不能加载"+e.getMessage());
        }
    }
}