Do weaker/less specific types in Java affect performance?

Question

Consider the following bits of Java code:

for(ArrayList<String> str : strList) {
    // something
}

for(Iterable<String> str : strList) {
    // something
}

Depending on what happens inside the loop, it may well not be necessary to use ArrayList or List, but we can instead of Iterable.

Does this have a performance benefit or is it purely a conceptual thing where you define it to tell the reader of the code that this is all you'll ever be doing with the object?

No performance benefit.

Berin Loritsch
– Berin Loritsch

2017-03-09 01:08:49 +00:00
Commented Mar 9, 2017 at 1:08 — Berin Loritsch
– Berin Loritsch, Commented Mar 9, 2017 at 1:08

Chris Thompson · Accepted Answer · 2017-03-09 01:09:46Z

1

It's purely conceptual. The language construct you're utilizing there requires the str object to implement the Iterable interface. Even if you pass an ArrayList (or subclass thereof), it's going to treat it as an Iterable

answered Mar 9, 2017 at 1:09

Chris Thompson

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KdgDev Over a year ago

Thanks for confirming

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