Java List to Map convertion

Question

is there any way to convert Java List to Map in Java 8? I have a List which I want to add the contents to Map

There are many ways. Details depend on how the elements of the list are supposed to relate to the entries in the map. — John Bollinger, Nov 24 '17 at 05:28

score 2 · Answer 1 · answered Nov 24 '17 at 05:42

2

Assume the class SomeType has a constructor and two fields named id and name

List<SomeType> list = new ArrayList<>();
        list.add(new SomeType(1, "a"));
        list.add(new SomeType(2, "b"));
        list.add(new SomeType(3, "c"));

        Map<Integer, String> result = list.stream().collect(
                Collectors.toMap(SomeType::getId, SomeType::getName));

answered Nov 24 '17 at 05:42

Türkmen Mustafa Demirci

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unless list contains duplicates – Eugene Nov 24 '17 at 08:26
exactly . @Eugene – Türkmen Mustafa Demirci Nov 24 '17 at 08:27

score 0 · Answer 2 · answered Nov 24 '17 at 05:38

I am assuming you have created a List named slist and a Map named map which is initialized from HashMap To create a map from list you need to run a for loop on the list.

for(String skey: slist){
        map.put(skey,yourLongValue); //Enter any Long value you desire or create a method which gets value dynamically like getLongValue()
}

Java List to Map convertion

2 Answers2