Java Stream How to - Reduce large Integer list to string

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Question

We would like to know how to reduce large Integer list to string.

Answer

import java.util.ArrayList;
import java.util.List;
/* ww  w  .  ja  v  a2  s .  co  m*/
public class Main {

  public static void main(String[] args) {

    List<Integer> l = getDatas();

    System.out.println(
        l.stream().map((a) -> (a.toString()))
        .reduce((a, b) -> (a + b ))
        .orElse("ko"));

  }

  public static List<Integer> getDatas() {

    List<Integer> l = new ArrayList(100);

    for (int i = 0; i < 99; i++) {
      l.add(i);
    }
    return l;
  }

}

The code above generates the following result.

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