Java enummap confusion

Question

Hi Can anyone help me in understanding the following line of code?

      private Map<EnumType, Pair<Long, Long>> processToProductLineAndIndustryMap = new EnumMap<EnumType, Pair<Long, Long>>(
        Collections.unmodifiableMap(Stream.of(
                new SimpleEntry<>(EnumType.SOME_TYPE,
                    Pair.of(Question.getProductLineQuestionId(), Question.getAdvertiserIndustryQuestionId())))
                    .collect(Collectors.toMap((e) -> e.getKey(), (e) -> e.getValue()))));

I am new to this. Have went through several articles online but could not able to figure out.

I want to create an unmodifiable map<EnumType, Pair<Long, Long>>. Based on enumtype i want to get the pair of Longs and see if it contains a particular long or not. Please help me in figuring out the best data structure for my usecase

The above is giving error "The method getKey() is undefined for object" ? — user3681970
– user3681970, Commented Apr 9, 2017 at 6:12
The Collections.unmodifiableMap doesn't do anything. This appears to be a complicated way to create a map with one entry. — Peter Lawrey
– Peter Lawrey, Commented Apr 9, 2017 at 6:16
I will edit this question with my requirement. Please help me in choosing the best data structure for it. :) — user3681970
– user3681970, Commented Apr 9, 2017 at 6:18

alayor · Accepted Answer · 2017-04-09 06:24:47Z

1

You can use Collections.singletonMap(key, value).

private Map<EnumType, Pair<Long, Long>> processToProductLineAndIndustryMap = new EnumMap<EnumType, Pair<Long, Long>>(
        Collections.singletonMap(EnumType.SOME_TYPE, Pair.of(Question.getProductLineQuestionId(), Question.getAdvertiserIndustryQuestionId())));

answered Apr 9, 2017 at 6:24

alayor

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user3681970 Over a year ago

Thanks for the help on weekends :)

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