new SimpleDateFormat always returns same reference for a given dateFormat

Question

I was trying to replicate a bug by using the same instance of SimpleDateFormat across multiple threads. However I got stuck with another problem and did not find any

Answer 1

They are different instances, try this

    DateFormat d1 = new SimpleDateFormat("ddMMyyyy");
    DateFormat d2 = new SimpleDateFormat("ddMMyyyy");
    System.out.println(d1 == d2);

it prints

false

as for the same java.text.SimpleDateFormat@c5bfbc60, they are based on class name and hashCode. According to Object.hashCode API it does not necessarily return distinct values for distinct objects