Win a copy of Think Java: How to Think Like a Computer Scientist this week in the Java in General forum!
  • Post Reply
  • Bookmark Topic Watch Topic
  • New Topic

why sometime we need to initialize integer variable ?

 
Alvin chew
Ranch Hand
Posts: 834
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
hi, wondering why sometime we need to initialize the integer variable but sometime not ?

example :


can somebody pls explain why is it so i must initialize num2 ? thank you very much for your time
 
William Brogden
Author and all-around good cowpoke
Rancher
Posts: 13061
6
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Class and instance variables are automatically given a starting value when the class is loaded or the instance is created. Variables declared inside a method are not.
Think about what the += operator does - it takes the existing value in a variable and adds to it. Therefore the compiler watches out for the possibility that num2 does not have a starting value assigned.
Automatically zeroing memory that a new object is going to occupy is part of the built-in security design of Java. In languages that don't do this, it is possible to grab a large hunk of memory that might have been used for data by a previous application and fish around in it for things like passwords.
Bill
 
  • Post Reply
  • Bookmark Topic Watch Topic
  • New Topic