import java.util.Map;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
 
class Ideone {
  public static void main(String[] args) {
    final Integer[] keys = IntStream.range(0, 12).boxed().toArray(Integer[]::new);
    final String[] values = new String[] {"Jan", "Feb", "Mar", "Apr", "Mai", "Jun",
        "Jul", "Aug", "Sep", "Okt", "Nov", "Dez"};
    final Map<Integer, String> map = fillMap(keys, values);
    System.out.println(map);
  }
 
  public static <K, V> Map<K, V> fillMap(K[] keys, V[] values) {
    return IntStream.range(0, keys.length)
        .boxed()
        .collect(Collectors.toMap(
            index -> keys[index],
            index -> values[index]));
  }
}

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