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javacollectionsrange
misnomer42
misnomer42

Reputation: 589

Сonvert List<integer> to Range<integer> in Map

I have a Map with the following values:

map.of.list={\
  {'2','4'} : '1', \
  {'4','6'} : '2', \
  {'6','8'} : '3' \
 }

@Value("#{${map.of.list}}")
private Map<List<Integer>, Integer> integerMap;

How can I convert this to a Map<Range<Integer>, Integer> rangesMap?

Type for Range is org.springframework.data.domain.Range.

Upvotes: 1

Views: 75

Answers (2)

aioobe
aioobe

Reputation: 421090

With this setup:

// Sample input
Map<List<Integer>, Integer> input = new HashMap<>();
input.put(List.of(1, 3), 5);
input.put(List.of(4, 7), 8);

// Map to hold the result
Map<Range<Integer>, Integer> result = new HashMap<>();

You can do it using...

Traditional for loop

// Code to convert
for (Map.Entry<List<Integer>, Integer> entry : input.entrySet()) {

    // Convert list key to Range
    List<Integer> key = entry.getKey();
    int from = key.get(0);
    int to = key.get(1);
    Range range = Range.rightOpen(from, to);

    Integer value = entry.getValue();
    
    result.put(range, value);
}

Using entrySet and toMap

Map<Range<Integer>, Integer> result = input.entrySet()
        .stream()
        .collect(Collectors.toMap(
                e -> Range.rightOpen(e.getKey().get(0), e.getKey().get(1)),
                Map.Entry::getValue
        ));

Using forEach as suggested by misnormer42

Map<Range<Integer>, Integer> result = new HashMap<>();
input.forEach((keys, values) -> {
    Range<Integer> integerRange = Range.rightOpen(keys.get(0), keys.get(1));
    ranges.put(integerRange, values);
});
return result;

Upvotes: 1

misnomer42
misnomer42

Reputation: 589

I can suggest to solve this problem in the following way:

public final class ConversionUtils {

    private ConversionUtils() {
    }

    public static Map<Range<Integer>, Integer> convertTo(Map<List<Integer>, Integer> fromProperties) {
        Map<Range<Integer>, Integer> result= new HashMap<>();
        fromProperties.forEach((keys, values) -> {
            Range<Integer> integerRange = Range.rightOpen(keys.get(0), keys.get(1));
            ranges.put(integerRange, values);
        });
        return result;
    }
}

Upvotes: 1

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