HashMap vs Switch statement performance

Question

A HashMap essentially has O(1) performance while a switch state can have either O(1) or O(log(n)) depending on if the compiler uses a tableswitch or lookup switch.

Under

Answer 1

If I have that kind of example I use Guava ImmutableMaps (sure You can use java 9 builder as well).

private static final Map EXAMPLE = ImmutableMaps.>builder()
    .put("a", "100")
    .put("b", "200")
    .build(); 

That way they are immutable and initated only once.

Sometimes I use strategy pattern that way:

private static final Map EXAMPLE = ImmutableMaps.>builder()
    .put("a", new SomethingCool())
    .put("b", new BCool())
    .build(); 

private static final Command DEFAULT= new DefCommand();

Use:

EXAMPLE.getOrDefault("a", DEFAULT).execute(); //java 8

About performance just pick readability. You will thank me later (1 year later) :D.