Most efficient way to check if an array contains a value in Java? [duplicate]

Question

I have a similar logic for a method in a Java Class (not the real code, this is simplified for example purposes).

private Boolean method(Boolean booleanValue, SomeObject object) {
  return booleanValue ? Arrays.asList(object.getStringsArray()).contains("string") : false;
}

A collaborator who assigned himself to check the PR gave the following comment:

This is inefficient. It is creating a new data structure only to iterate it and check if there is a certain string.

The getStringsArray() method returns a String[], so will using a for-loop be better than Arrays.asList()?

Which way is more efficient to achieve this?

Arrays.asList just returns a wrapper, so that's not a problem. object.getStringsArray might be a problem, depending on what that does and whether there might be better ways to check for this string. — user2357112
– user2357112, Commented Jun 17, 2016 at 16:22
I disagree with it being inefficient. List objects are backed by an array, so there is no performance loss. Even the canonical answer for how to do this uses this method. — castletheperson
– castletheperson, Commented Jun 17, 2016 at 16:22
We can't really say for sure whether your real code was good or bad, since it probably looked very different from this. Using Boolean instead of boolean here is a bad idea, and Object has no getStringsArray method. — user2357112
– user2357112, Commented Jun 17, 2016 at 16:24
This is not the real code, is more like a pseudo-code, the real method doesn't looks like this, Im not able to post the original code here. — Alfredo Bejarano
– Alfredo Bejarano, Commented Jun 17, 2016 at 17:07

azurefrog · Accepted Answer · 2016-06-17 16:30:34Z

6

Your co-worker is incorrect when they assert that your method is creating a new data structure.

If you look at the API for Arrays.asList(), it says that it

Returns a fixed-size list backed by the specified array.

There is no reason to write your own code to iterate over the array when you can just wrap a List around it, and use its built-in methods.

answered Jun 17, 2016 at 16:30

azurefrog

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2 Comments

Alfredo Bejarano Over a year ago

Hey Thank you! I was worried because I can't come up with another solution. Now with the API documentation I have proof about this is the best method.

castletheperson Over a year ago

If you also want proof from another SO question, see this popular answer. This might actually be a duplicate of that question...

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