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find the index of the longest string in an arraylist

Ashley Feng

Joined: Jan 12, 2013
Posts: 1
i need to return the index of the longest string in the arraylist in java
so far i have

but all it does is return 0
Vijay Vishwa
Ranch Hand

Joined: Nov 21, 2010
Posts: 32
Hi Ashley,
I see there is no problem in the code and logic. It works fine.
Can you first print the ArrayList and see what are the values inside. It may be that the First string is largest itself.

Here how I tested it.

Output is 2

SCJP 5.0 OCBCD 5.0(Formerly SCBCD)
Winston Gutkowski

Joined: Mar 17, 2011
Posts: 8945

Ashley Feng wrote:so far i have...

Like Vijay, I can't see anything logically wrong with your method, but it does contain a few possibilities for improvement:

1. I'd definitely get into the habit of using for-each loops for collections, because
(a) they usually have less boilerplate.
(b) they're less likely to be affected by the type of Collection they operate on.
For example, your method could be re-written:and it will work just as fast whether your List is an ArrayList or a LinkedList (your loop won't).
Their main disadvantage is that you have to define the index outside the loop, but in this case I reckon it's probably worth it.

2. Prefer variables to method calls. Your loop has to call size() for each iteration, butonly calls it once. Now in this case it probably doesn't make a lot of difference, but it is worth remembering.

3. Cover all your bases. Your method silently returns a valid index (0) if the supplied List is empty, whereas the example above returns -1. An alternative is to throw an Exception, which is equally valid. Just remember to allow for it and document what happens.



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