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  1. #1
    XmisterIS is offline Member
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    Default In-loop declarations and performance question ...

    Consider the following two code snippets in which vect is a vector of objects of type Thing.

    Snippet 1:
    Java Code:
    for (Enumeration<Thing> en = vect.elements(); en.hasMoreElements(); )
    {
      Thing item = en.nextElement();
    
      //Rest of code here.
    }

    Snippet 2:
    Java Code:
    Thing item;
    
    for (Enumeration<Thing> en = vect.elements(); en.hasMoreElements(); )
    {
      item = en.nextElement();
    
      //Rest of code here.
    }

    In the case of Snippet 1, is there any extra overhead associated with placing the declaration of item in the loop rather than outside, as in Snippet 2? Or is there no difference?

  2. #2
    Tolls is offline Moderator
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    Default

    The former is the preferable way of doing this assuming you have no need for the final Thing object outside of the loop. The basic "rule" is to keep things in the scope in which they're needed, and no more.

    As for performance? Unless you actually have a performance issue with the code do not worry about it. Do not go down the premature optimisation route...you rarely if ever gain anything. Write good, maintainable code.

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