@Override
 public boolean equals(Object obj){
  if(this == obj){
   return true;
  }
  if(obj == null){
   return false;
  }
  if(!(obj instanceof Course)){
   return false;
   Course course = (Course)obj;
   if(this.name == null){
    return true;
   }else
    return false;
   }else{
    if(this.name.equals(course.name)){
     return true;
    }else
     return false;
    }
  }