This week's book giveaway is in the JavaScript forum.
We're giving away four copies of Svelte and Sapper in Action and have Mark Volkmann on-line!
See this thread for details.
Win a copy of Svelte and Sapper in Action this week in the JavaScript forum!
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
programming forums Java Mobile Certification Databases Caching Books Engineering Micro Controllers OS Languages Paradigms IDEs Build Tools Frameworks Application Servers Open Source This Site Careers Other all forums
this forum made possible by our volunteer staff, including ...
  • Campbell Ritchie
  • Ron McLeod
  • Paul Clapham
  • Bear Bibeault
  • Junilu Lacar
  • Jeanne Boyarsky
  • Tim Cooke
  • Henry Wong
Saloon Keepers:
  • Tim Moores
  • Stephan van Hulst
  • Tim Holloway
  • salvin francis
  • Frits Walraven
  • Scott Selikoff
  • Piet Souris
  • Carey Brown

Why to create Final Class Object?

Ranch Hand
Posts: 87
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

I am looking on my senior code he have created a "final" class and make it's object and write a comment like this :

public final class AppUtil {
// so that nobody can accidentally create an AppUtil object
private AppUtil()

* formatName - formats a name string given the individual name fields

Why so If it's a final class then nobody can modify it then why it's safe to create a it's object??
Posts: 21999
Eclipse IDE Spring VI Editor Chrome Java Ubuntu Windows
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
A final class cannot have any subclasses. This just means that nobody can create a subclass that modifies behaviour of the final class by modifying internal data or overriding methods so they behave differently. A good example is java.lang.String; by making it final, it is ensured that String objects are and always will be immutable.

As for your example, this is a so-called utility class. It's final so nothing can subclass it, and it has only a private constructor so that no other code can instantiate it. This class most likely only contains static methods.

Actually, utility classes don't even need to be final themselves. Because there is only a private constructor and no public, protected or package visible one, subclasses cannot call super(...) because that just isn't visible. It is good practive to do so nonetheless.
Ranch Hand
Posts: 262
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
It depends on what you have in the code.

A final class is one thing and private constructor is another.

A final class means that no one can extends it. It could not have

From the comment of you first method(?), i guest that your class AppUtil provides utilities methods for the application.
Those methods are usely static. You don't need to call them on an instance.For that reason the constructor is private.

If there was no constructor, the compiler would have provide a default one.
Thus you can create an instance of AppUtil by new AppUtil();
what if we put solar panels on top of the semi truck trailer? That could power this tiny ad:
the value of filler advertising in 2020
    Bookmark Topic Watch Topic
  • New Topic