• 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
  • Paul Clapham
  • Ron McLeod
  • Tim Cooke
  • Junilu Lacar
Sheriffs:
  • Rob Spoor
  • Devaka Cooray
  • Jeanne Boyarsky
Saloon Keepers:
  • Jesse Silverman
  • Stephan van Hulst
  • Tim Moores
  • Carey Brown
  • Tim Holloway
Bartenders:
  • Jj Roberts
  • Al Hobbs
  • Piet Souris

equals from Integer

 
Ranch Hand
Posts: 808
1
Android Eclipse IDE Java
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
From K&B book:

Integer i343 = 343;
long l343 = 343;
System.out.println(i343.equals(l343));

Why the output is false?
 
Ranch Hand
Posts: 157
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Integer's equals compares if the object is an instance of the same class, that's why it returns false.
 
Lucas Smith
Ranch Hand
Posts: 808
1
Android Eclipse IDE Java
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
OK and the same rule for the rest of the wrappers?

I have to think
equals which is overriden should check:
1) if the reference is null or if the reference points to the same object
2) if getClassName() fits to another :P
3). meaningfull comparations
 
Eduardo Bueno
Ranch Hand
Posts: 157
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Yes.

Overriden equals should first check if the reference points to the same object, then compares if it is not an instance of the class, and then compare it's attributes.
 
You showed up just in time for the waffles! And this tiny ad:
Building a Better World in your Backyard by Paul Wheaton and Shawn Klassen-Koop
https://coderanch.com/wiki/718759/books/Building-World-Backyard-Paul-Wheaton
reply
    Bookmark Topic Watch Topic
  • New Topic