Java design pattern : Singleton

gistfile1.java

public class MySingleton {
  
  private static MySingleton instance;
   
  public String customVar;
   
  public MySingleton()
  {
    if (instance == null)
    {
      // Create the instance
      instance = new MySingleton();
    }
  }
 
  public static MySingleton getInstance()
  {
    // Return the instance
    return instance;
  }
   
  private MySingleton()
  {
    // Constructor hidden because this is a singleton
  }
}