CODEWITHSUNDEEP
javaguava
XoXo
XoXo

Reputation: 1599

In guava, what is the difference (if any) between Lists.newArrayList() and e.g. Ints.asList() for primitive types

I have always been using guava's collection utilities to create a list:

List<Integer> foo = Lists.newArrayList(1, 2, 3);

Lately I found the primitives utilities, which allows this:

List<Integer> bar = Ints.asList(1, 2, 3);

From the documentation, both foo and bar are mutable:

foo.set(0, 100);
bar.set(0, 100);

So what is the difference (if any) between the two, for primitive types like int?

Upvotes: 1

Views: 268

Answers (1)

Sotirios Delimanolis
Sotirios Delimanolis

Reputation: 280141

Primitives don't work with generics. This

List<Integer> foo = Lists.newArrayList(1, 2, 3);

would incur the cost of boxing each int value and wrapping the whole thing in an Integer[] to be passed to newArrayList. The List returned is not fixed size.

This

List<Integer> bar = Ints.asList(1, 2, 3);

would only incur the cost of wrapping the three arguments in an int[] as that's the parameter type. The List returned is fixed size

Upvotes: 6

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