Is there a standard java exception class that means “The object was not found”?

Question

Consider a function of the following general form:

Foo findFoo(Collection foos, otherarguments)
throws ObjectNotFoundException {
    for(Foo foo :         


        

Answer 1

Exceptions are created to mark exceptional behaviour. In my opinion, object not found situation is not exceptional. I would rewrite your method to return null, if user is not found.

User findUserByName(Collection users, String name) {
   for(User user : users){
       if(user.getName().equals(name)){
           return user;
      }
    }
  return null; 
}

This is standard behaviour for many Java Collections. For example, http://docs.oracle.com/javase/7/docs/api/java/util/Map.html#get(java.lang.Object) will return null, when no entry with specified key is in the map.

You should avoid relying on exceptions in your programms logic.