Win a copy of Node.js Design Patterns: Design and implement production-grade Node.js applications using proven patterns and techniques this week in the Server-Side JavaScript and NodeJS 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 Pie Elite all forums
this forum made possible by our volunteer staff, including ...
Marshals:
  • Campbell Ritchie
  • Ron McLeod
  • Rob Spoor
  • Tim Cooke
  • Junilu Lacar
Sheriffs:
  • Henry Wong
  • Liutauras Vilda
  • Jeanne Boyarsky
Saloon Keepers:
  • Jesse Silverman
  • Tim Holloway
  • Stephan van Hulst
  • Tim Moores
  • Carey Brown
Bartenders:
  • Al Hobbs
  • Mikalai Zaikin
  • Piet Souris

what does collections.singletonlist do

 
Ranch Hand
Posts: 95
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
HI all

what does the collections.singletonlist(Object o) method do?

What do we mean by the term immutable list and singleton list?
 
Rancher
Posts: 13459
Android Eclipse IDE Ubuntu
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
An immutable List (also referred to as an unmodifiable List) cannot have it's contents changed. The methods to add or remove items will throw exceptions if you tr to alter the contents.

A singleton List contains only that item and cannot be altered.
 
Praveen Seluka
Ranch Hand
Posts: 95
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Ya I understood the terms.thanks
I came across this code.But why do we create a list with a single object.
Can you say what is the advantage in using collections.singletonlist() ?

Thanks
Praveen SP
 
David O'Meara
Rancher
Posts: 13459
Android Eclipse IDE Ubuntu
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
If you want an empty list, you can use Collections.EMPTY_LIST or emptyList().
If you want an unmodifiable List containing a single item, compare Collections.singletonlist("My Object") to the code doing the same.
 
Praveen Seluka
Ranch Hand
Posts: 95
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
thanks for your answer david
 
reply
    Bookmark Topic Watch Topic
  • New Topic