Win a copy of Murach's MySQL this week in the JDBC and Relational Databases 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
  • Jeanne Boyarsky
  • Ron McLeod
  • Paul Clapham
  • Liutauras Vilda
Sheriffs:
  • paul wheaton
  • Rob Spoor
  • Devaka Cooray
Saloon Keepers:
  • Stephan van Hulst
  • Tim Holloway
  • Carey Brown
  • Frits Walraven
  • Tim Moores
Bartenders:
  • Mikalai Zaikin

Wrapper types comparison doubt

 
Ranch Hand
Posts: 39
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Chapter 6, Self test Q3.

Correct answers - B,C,D

How come answer is also D option??
I know that two Integer wrapper objects can be compared.

Using simple relational operator,
How can a short object be compared with an Integer object?
How does Java compare the two different wrapper's values??
 
author
Posts: 23949
142
jQuery Eclipse IDE Firefox Browser VI Editor C++ Chrome Java Linux Windows
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator

Kedar Pethe wrote:Chapter 6, Self test Q3.

Correct answers - B,C,D

How come answer is also D option??
I know that two Integer wrapper objects can be compared.

Using simple relational operator,

How can a short object be compared with an Integer object?
How does Java compare the two different wrapper's values??



The answer is .... it depends.

If you are using a "==" or "!=" as the operator, it will do an instance comparison, meaning whether the two instances are the same instance.... and of course, this will fail to compile as Short and Integer are not sub/super classes of each other.

Otherwise, such as what you did in the example, it will do a value comparison, meaning it will unbox both sides first.

Henry
 
Kedar Pethe
Ranch Hand
Posts: 39
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator

Henry Wong wrote:
If you are using a "==" or "!=" as the operator, it will do an instance comparison, meaning whether the two instances are the same instance.... and of course, this will fail to compile as Short and Integer are not sub/super classes of each other.
Otherwise, such as what you did in the example, it will do a value comparison, meaning it will unbox both sides first.
Henry



Ok.. but is it that while using >,<,<=,>= whatever be the two wrapper types(Byte,Short,Integer,Long,Float,Double) comparison will always take place on their values??
 
Kedar Pethe
Ranch Hand
Posts: 39
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator

Henry Wong wrote:
If you are using a "==" or "!=" as the operator, it will do an instance comparison, meaning whether the two instances are the same instance.... and of course, this will fail to compile as Short and Integer are not sub/super classes of each other.

Otherwise, such as what you did in the example, it will do a value comparison, meaning it will unbox both sides first.

Henry


I tried, whatever be the two operands for relational operators, comparison always takes place on their values and gives correct output, without any error!!
 
With a little knowledge, a cast iron skillet is non-stick and lasts a lifetime.
reply
    Bookmark Topic Watch Topic
  • New Topic