Here is one class:

public class circle {

// private instance variable
private double radius = 1;
private string color = "red";

// default constructor w/out an argument
public circle() {
}

// constructor that takes in double argument which is assigned to radius
public circle(double r) {

radius = r;
}
public circle (double r, string c){

}

// public method "getradius"
public double getradius() {
return radius;
}