The example you have mentioned is of an Immutable Objects. Its widely used concepts in programming languages.
Quoting from the link above. The advantages are
- are simple to construct, test, and use
- are automatically thread-safe and have no synchronization issues
- do not need a copy constructor
- do not need an implementation of clone
- allow hashCode to use lazy initialization, and to cache its return value
- do not need to be copied defensively when used as a field
- make good Map keys and Set elements (these objects must not change state while in the collection)
- have their class invariant established once upon construction, and it never needs to be checked again
- always have "failure atomicity" (a term used by Joshua Bloch) : if an immutable object - throws an exception, it's never left in an undesirable or indeterminate state
