using Optional to validate null when getting value from map

Question

I have this line

List<Integer> someListWithLongName = someMapWithLongName.containsKey(someObjectWithLongName.get()) 
    ? someMapWithLongName.get(someObjectWithLongName.get()) 
    : Collections.emptyList();

That I wanted to change to make it a bit more readable, so I chose:

List<Integer> someListWithLongName = Optional.of(someMapWithLongName.get(someObjectWithLongName.get())
    .orElse(Collections.emptyList())

But I was told that the purpose of Optional is different. However, I'm failing to see why.
Is it really so? why?

related IMO

Eugene
– Eugene

2018-10-25 20:36:23 +00:00
Commented Oct 25, 2018 at 20:36 — Eugene
– Eugene, Commented Oct 25, 2018 at 20:36
docs.oracle.com/javase/8/docs/api/java/util/…

JB Nizet
– JB Nizet

2018-10-25 20:36:54 +00:00
Commented Oct 25, 2018 at 20:36 — JB Nizet
– JB Nizet, Commented Oct 25, 2018 at 20:36

Ousmane D. · Accepted Answer · 2018-12-04 01:58:20Z

3

Some people will have different views on this but a good practice is to always use something the way it was intended.

see this answer for consequences of misusing the Optional<T> type.

instead of your current solution, a better solution hinted by @JB Nizet would be using Map::getOrDefault available as of JDK8.

List<Integer> result = map.getOrDefault(key, Collections.emptyList());

answered Dec 4, 2018 at 1:58

Ousmane D.

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