hashCode can be the same for different instances of an inner class?

Question

I have a custom SwingWorker inner class. I found several times their hashcode are the same for different instances of it. Why is that? Normal?

EDIT:

The inner class I have is a subclass of the SwingWorker class.

Answer 1

Hash codes do not need to be different for different objects. The only requirement is that they must be the same for equal objects.

If it is a concern that your SwingWorker inner classes produce identical hash codes, you could override the hashCode method in your inner class to provide hash codes that suit your needs better. Of course you would need to override equals as well to supply the matching logic to both methods:

final int workerId = 123;
SwingWorker<String,Object> myWorker = new SwingWorker<String,Object> {
   @Override
   public String doInBackground() {
       ...
   }
   @Override
   protected void done() {
       ...
   }
   @Override
   public int hashCode() {
       return workerId;
   }
   @Override
   public boolean equals(Object other) {
       return other == this;
   }
}