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Subject: Re: What's the best way to make a cross string set?
Date: Mon, 31 Jul 2017 19:24:33 -0400
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On 7/31/2017 8:24 AM, Eric Douglas wrote:
> You're saying declaring a variable as a List is more efficient even
> if you know it's going to be instantiated as ArrayList?  I've always
> tried to avoid that because it's one more line in the import section,
> and I never use * imports because that just sounds confusing at best
> messy at worst when you get into the same class names in multiple
> packages.

List<X> lst = new ArrayList<X>();

is often considered better than:

ArrayList<X> lst = new ArrayList<X>();

The import cost nothing.

And by using the interface List<> then it is possible to change
the actual type later to a different List<> implementation without
worrying about code using methods only available in ArrayList<>.

Reference:

Effective Java 2nd Ed / Bloch Item 52.

The question comes up frequently.

SO examples:

https://stackoverflow.com/questions/2279030/type-list-vs-type-arraylist-in-java
https://stackoverflow.com/questions/9852831/polymorphism-why-use-list-list-new-arraylist-instead-of-arraylist-list-n
https://stackoverflow.com/questions/18329311/reason-for-list-list-new-arraylist

Arne