PHP Sort

sort.php

<?php

class Soldier
{
    private $name;
    private $height;

    public function __construct($name)
    {
        $this->name = $name;
    }

    public function setHeight(int $height)
    {
        $this->height = $height;
    }

    public function getHeight()
    {
        return $this->height;
    }

    public function __toString()
    {
        return "{$this->name}: {$this->height}";
    }
}

class Line
{
    private $line = [];

    public function add(Soldier $soldier)
    {
        $this->line[] = $soldier;
        return $this;
    }

    public function sort()
    {
        for ($j = 0; $j < count($this->line) - 1; $j++) {
            for ($i = 0; $i < count($this->line) - $j - 1; $i++) {
                if ($this->line[$i]->getHeight() > $this->line[$i + 1]->getHeight()) {
                    $tmp_var = $this->line[$i + 1];
                    $this->line[$i + 1] = $this->line[$i];
                    $this->line[$i] = $tmp_var;
                }
            }
        }
    }

    public function print()
    {
        foreach ($this->line as $soldier) {
            echo $soldier . "\n";
        }
    }
}

$vova = new Soldier('Vova');
$vova->setHeight(165);

$vitya = new Soldier('Vitya');
$vitya->setHeight(164);

$petr = new Soldier('Petr');
$petr->setHeight(190);

$line = new Line();
$line
    ->add($vova)
    ->add($vitya)
    ->add($petr);

$line->sort();
$line->print();