=====Java=====
Merci [[http://www.amazon.fr/dp/0596007124|Head First Design Pattern]] et [[https://en.wikipedia.org/w/index.php?title=Double-checked_locking|Double-checked locking]] {{ :helloworld:design_pattern:singleton:double-checked_locking_-_wikipedia_2020-04-27_10_17_20_am_.html |Archive du 17/04/2020 le 27/04/2020}}

<file java singleton.java>
public class Singleton
{
  private volatile static Singleton instance = null;

  private Singleton ()
  {
  }

  public static Singleton getInstance ()
  {
    Singleton result = instance;
    if (result == null)
    {
      synchronized (Singleton.class)
      {
        result = instance;
        if (result == null) {
          instance = result = new Singleton ();
        }
      }
    }
    return result;
  }
}
</file>