a function which takes a list of strings and returns each line prepended by the correct number

URL Link //n.sfs.tw/15357

2021-08-22 16:16:20 By

Write a function which takes a list of strings and returns each line prepended by the correct number.

The numbering starts at 1. The format is n: string. Notice the colon and space in between.

Examples:

number(Arrays.asList()) # => []
number(Arrays.asList("a", "b", "c")) // => ["1: a", "2: b", "3: c"]

my solution according to: https://github.com/RomanBulinski/Testing1-2-3.git

 

 
 

import java.util.List;

import java.util.concurrent.atomic.AtomicInteger;
  import java.util.stream.Collectors;
   
  import static java.util.stream.Collectors.toList;
   
  public class Main {
   
  public static List<String> number(List<String> lines) {
  AtomicInteger i = new AtomicInteger(1);
  return lines.stream().map(e -> i.getAndIncrement() + ": " + e).collect(Collectors.toList());
   
  }
   
 

}

 

best practice:

import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

class LineNumbering {
    static List<String> number(List<String> lines) {
    if (lines.size() == 0) return lines;
    return IntStream.range(0, lines.size())
            .mapToObj(n -> String.format("%d: %s", n+1, lines.get(n)))
            .collect(Collectors.toList());
    }
}