How do i create a single instance of a class inside a servlet ?

Question

how do i create a single instance of a class inside a servlet ?
public void doGet(HttpServletRequest request,HttpServletResponseresponse) throws ServletException, IOException {
// call a class here. this class should create only single instance, //though we know servlet are multithreaded. if, at any time 10 user comes //and access this servlet still there would one and only one instance of //that class.
How do i make my class ? class is supposed to write some info to text file.

Answer 1

i have a class MyClass. this class creates a thread.
i just want to run MyClass only once in my servlet. i am afriad, if there are 10 users access this servlet ,then 10 Myclass instance wouldbe created. i just want to avoid this. i want to make only one instance of this class.
How do i do ?
they have this code in the link you provided.
public class SingletonObject
  private SingletonObject()
    // no code req'd
  public static SingletonObject getSingletonObject()
    if (ref == null)
        // it's ok, we can call this constructor
        ref = new SingletonObject();          
    return ref;
  public Object clone()
     throws CloneNotSupportedException
    throw new CloneNotSupportedException();
    // that'll teach 'em
  private static SingletonObject ref;
}i see, they are using clone !, i dont need this. do i ? shouldi delete that method ?
where do i put my thread's run method in this snippet ?