private?Double?radius;
public?Double?getArea()?{
if?(radius?==?null?||?radius?<=?0)?{
throw?new?RuntimeException("radius不合法");
}
return?Math.PI?*?radius?*?radius;
}
public?Double?getLength()?{
if?(radius?==?null?||?radius?<=?0)?{
throw?new?RuntimeException("radius不合法");
}
return?Math.PI?*?2?*?radius;
}
public?Double?getRadius()?{
return?radius;
}
public?void?setRadius(Double?radius)?{
this.radius?=?radius;
}
}import?java.util.Scanner;
public?class?App?{
public?static?void?main(String[]?args)?{
Scanner?input?=?new?Scanner(System.in);
Circle?circle?=?new?Circle();
while?(true)?{
Double?radius?=?input.nextDouble();
circle.setRadius(radius);
System.out.println(String.format("%.2f?%.2f",?circle.getArea(),
circle.getLength()));
circle.setRadius(radius?*?2);
System.out.println(String.format("%.2f?%.2f",?circle.getArea(),
circle.getLength()));
}
}
}