How to add missing elements to an array?

Question

Java

Good day.
There is a tree of elements, for example, directories. In the 'correct' form, it looks like this:
A1, A1\BB1, A1\BB1\CCC1, A2, A2\BB1, A2\BB1\CCC1
Algorithm for the arrangement of array elements: if there is an element A1\BB1\CCC1, then it is preceded by 'parent' elements A1\BB1 and A1.
The question is, if this array has missing elements, as in this case:
A1, A1\BB1\CCC1, A2\BB1, A2\BB1\CCC1
how to properly parse its strings in order to get the original form of the array again?
Thanks to.

Answer 1

For example like this. Not optimized :-)

package my.com;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.Set;
import java.util.TreeSet;

public class Paths {
  public static void main(String[] args) {
    String str = "A1, A1\\BB1\\CCC1, A2\\BB1, A2\\BB1\\CCC1";
    ArrayList<String> paths = new ArrayList<String>(Arrays.asList(str.split(",")));

    System.out.println("======  Беган =======");
    System.out.println("Было");
    for(String i:paths){
      System.out.println(i);
    }
    
    Set<String> out = new TreeSet<String>(new Comparator<String>() {

      @Override
      public int compare(String o1, String o2) {
        return o2.compareTo(o1);
      }
      
    });
    for(String i : paths) {
      ArrayList<String> path = new ArrayList<String>(Arrays.asList(i.trim().split("\\\\")));
  
      for(int j = 1; j <= path.size(); j++) {
        List<String> s = path.subList(0, j);
        out.add(String.join("\\",s));
      }
    }

    System.out.println("=================");
    System.out.println("Сортировка туда");
    for(String i:out) {
      System.out.println(i);
    }

    System.out.println("=================");
    System.out.println("Сортировка обратно");
    Set<String> out1 = new TreeSet<String>();
    out1.addAll(out);
    for(String i:out1) {
      System.out.println(i);
    }
    System.out.println("======= Доне ======");
    
  }
}

======  Беган =======
Было
A1
 A1\BB1\CCC1
 A2\BB1
 A2\BB1\CCC1
=================
Сортировка туда
A2\BB1\CCC1
A2\BB1
A2
A1\BB1\CCC1
A1\BB1
A1
=================
Сортировка обратно
A1
A1\BB1
A1\BB1\CCC1
A2
A2\BB1
A2\BB1\CCC1
======= Доне ======

Answer 2

Because you don't call it.
Add a line $a = $el->myValue;and $n will be printed.

Answer 3

Precisely everything is fine (checked) according to the code?
php.net/manual/ru/language.oop5.overloading.php