CODEWITHSUNDEEP
java
Zheden
Zheden

Reputation: 593

java get sorted values from immutablemap based on list of keys

I have ImmutableMap<String, Integer> and List<String> that defines the order. I want to get ImmutableList<Integer> with that order. For example:

map (<"a", 66>, <"kk", 2>, <"m", 8>) 

list ["kk", "m", "a"]

As result I want another list of values from given list with defined order :[2, 8, 66].

What is the best way to do it in java?

Upvotes: 0

Views: 918

Answers (2)

Kushan
Kushan

Reputation: 10703

Try this,

List<Integer> numbers= new ArrayList<>(map.size());
for(String l : list) {
    numbers.add(map.get(l));
}

example from Java 8 streams 

List<Integer> numbers= list.stream().map(map::get).collect(Collectors.toList());

Java SE 8 to the rescue! The Java API comes with a new abstraction called Stream that lets you process data in a declarative way. Streams can leverage multi-core architectures without you having to write a single line of multithread code.

Upvotes: 1

Nathan Bierema
Nathan Bierema

Reputation: 1933

Without streams you can use a simple for loop:

List<Integer> valuesInOrder = new ArrayList<>(map.size());
for(String s : list) {
    valuesInOrder.add(map.get(s));
}

If you want to use streams you could do:

List<Integer> valuesInOrder =
    list.stream().map(map::get).collect(Collectors.toList());

Upvotes: 5

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