Want to protect your cyber security and still get fast solutions? Ask a secure question today.Go Premium

x
?
Solved

Vector instantiation

Posted on 2004-10-04
5
Medium Priority
?
380 Views
Last Modified: 2011-09-20
Hi,

 I would like to know the difference between
 instantiation or initialization of Vector in Constructor and initializing as instance variable.

for eg:

case A
------
class x
{
       Vector v = new Vector();
       x()
      {
              // some initialization
      }
}

And
case B
------
class x
{
       Vector v = null;
       x()
      {
              v = new Vector();
              // some initialization
      }
}

Same with Array list also,
Which is better, is there any performance or any other issues declaring it in case B with respect to case A.

regards,
alpjose
0
Comment
Question by:alpjose
  • 3
  • 2
5 Comments
 
LVL 92

Expert Comment

by:objects
ID: 12223685
i reckon the first one is best as it removes any confusion about what the initial value of the variable is.
0
 

Author Comment

by:alpjose
ID: 12223697
I would like to understand it more clearly, so i would ask u another question.
If i initialise it to null, then will there be any confusion??
0
 
LVL 92

Expert Comment

by:objects
ID: 12223715
In case B it is initialized to null initially, and then later it is changed to reference a new empty Vector (which is it's intended initial value). So theres a block of code where it is null even though that is not it's intended initial value.

Its a minor point but I just like to initialize any variable as soon as possible.
0
 

Author Comment

by:alpjose
ID: 12223752
Will it have any performance issue??
0
 
LVL 92

Accepted Solution

by:
objects earned 200 total points
ID: 12223777
no performance differences
0

Featured Post

Upgrade your Question Security!

Your question, your audience. Choose who sees your identity—and your question—with question security.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Java contains several comparison operators (e.g., <, <=, >, >=, ==, !=) that allow you to compare primitive values. However, these operators cannot be used to compare the contents of objects. Interface Comparable is used to allow objects of a cl…
Are you developing a Java application and want to create Excel Spreadsheets? You have come to the right place, this article will describe how you can create Excel Spreadsheets from a Java Application. For the purposes of this article, I will be u…
Viewers will learn about the regular for loop in Java and how to use it. Definition: Break the for loop down into 3 parts: Syntax when using for loops: Example using a for loop:
This tutorial explains how to use the VisualVM tool for the Java platform application. This video goes into detail on the Threads, Sampler, and Profiler tabs.
Suggested Courses
Course of the Month10 days, 17 hours left to enroll

571 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question