package ldz;
public class Circle {
private double radius;
public double getRadius() {
return radius;
}
public void setRadius(double radius) throws CircleException {
if(radius<0){
throw new CircleException(radius);
}
else;this.radius = radius;
}
public void show(){
System.out.println("area="+3.14*radius*radius);
}
}
package ldz;
public class CircleException extends Exception {
private double radius;
public CircleException(double radius) {
super();
this.radius = radius;
}
@Override
public String toString() {
return "radius:r="+radius+",needs to be a positive number.";
}
}
package ldz;
public class TestException {
public static void main(String[] args) {
Circle c= new Circle();
try{
c.setRadius(-2.0);
}
catch(Exception e){
System.out.println("Custom exception:"+e.toString()+"");
}
c.show();
}
}
