这个Java基础题怎么编写

编写一个测试类，类名为 TestCircle,利用 Circle 类计算半径为 5.0 的圆的面积， 并调用 show()方法输出圆相关信息。

参考如下：

public class Circle {

    private double radius;

    private double area;

    public Circle(double radius) {
        this.radius = radius;
    }

    public double calc() {
        area = Math.PI * radius *radius;
        return area;
    }

    public void show() {
        StringBuilder sBuilder = new StringBuilder();
        sBuilder.append("radius=").append(radius)
                .append(",area=").append(area);
        System.out.println(sBuilder.toString());
    }
}

public class TestCircle {

    public static void main(String[] args) {
        Circle circle = new Circle(5.0);
        circle.calc();
        circle.show();
    }
}

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public class TestCircle {
    public static void main(String[] args) {
        // 创建一个半径为5的圆
        Circle circle = new Circle(5.0);
        // 打印圆信息
        circle.show();
    }
}
class Circle{
    private Double r;
    private Double area;
    private Double perimeter;
    private static final Double Pi=3.14159;
    Circle(){}
    Circle(Double r){
        this.r=r;
    }

    public Double getR() {
        return r;
    }

    public void setR(Double r) {
        this.r = r;
    }

    public Double getArea() {
        if(this.r==null){
            return 0.0;
        }
        return this.r*this.r*Pi;
    }

    public Double getPerimeter() {
        if(this.r==null){
            return 0.0;
        }
        return 2*Pi*this.r;
    }

    public void show(){
        System.out.println("圆信息:{半径:"+this.r+",周长:"+String.format("%.2f",getArea())+",面积:"+String.format("%.2f",getPerimeter())+"}");
    }
}