Win a copy of Escape Velocity: Better Metrics for Agile Teams this week in the Agile and Other Processes 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
  • Liutauras Vilda
  • Tim Cooke
  • Paul Clapham
  • Jeanne Boyarsky
Sheriffs:
  • Ron McLeod
  • Frank Carver
  • Junilu Lacar
Saloon Keepers:
  • Stephan van Hulst
  • Tim Moores
  • Tim Holloway
  • Al Hobbs
  • Carey Brown
Bartenders:
  • Piet Souris
  • Frits Walraven
  • fred rosenberger

String variables

 
Greenhorn
Posts: 24
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
when we declare a string variable as
String s = null
then the string referrence variable s does not refer to any String object.
How does the statement s+=s
produce a value of nullnull??
does this mean that when s does not refer to any string object it gets a value of null. but still any other operations on the variable using the dot operator results in nullpointerexception.
 
Ranch Hand
Posts: 637
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
A null-pointing String reference when asked to cough up its String value with the + op, returns the literal 'null'. When any method is invoked though, there has to be a valid object to the ref.
 
author
Posts: 23928
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
This is actually related to the StringBuffer (StringBuilder) class. Normally, when you try to append an object to the string buffer, it will use the toString() method to get the string to append. However, if the object in question is not available (null), the append() method will append the string value of "null".

How is this related? The adding of strings are actually syntactic sugar for append() method calls to string buffers.

Henry
 
Slime does not pay. Always keep your tiny ad dry.
Garden Master Course kickstarter
https://coderanch.com/t/754577/Garden-Master-kickstarter
reply
    Bookmark Topic Watch Topic
  • New Topic