Java Stream How to - Map integer and return double

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Question

We would like to know how to map integer and return double.

Answer

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.function.Function;
/*  w ww .ja va  2s  .  c om*/
public class Main {
   public static void main(String[] args) {
      List<Integer> numbers = Arrays.asList(1, 2, 3);

      // accepting integer, returning double
      System.out.println(mapIt(numbers, x -> Math.pow(10, x)));
   }

   public static <T, R> List<R> mapIt(List<T> candidates, Function<T, R> mapper) {
      List<R> mappedList = new ArrayList<>();

      for(T candidate : candidates) {
         mappedList.add(mapper.apply(candidate));
      }

      return mappedList;
   }
}

The code above generates the following result.

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