Calling a method in the main activity from class adapter

Question

Here is my code in my AddClassAdapter recylerview using firebase below on "onBindViewHolder":

holder.editBtn.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        UserClasses userClasses = new UserClasses();
        userClasses.openEditClassDialog();
    }
});

And here is the "openEdiClassDialog" method in my main activity:

public void openEditClassDialog(){
    UserClassEditDialog userClassEditDialog = new UserClassEditDialog();
    userClassEditDialog.show(getSupportFragmentManager(),"user class dialog");
}

My problem is, If I clicked the edit button of an item in the recylerview adapter, this error shows in my logcat:

java.lang.IllegalStateException: FragmentManager has not been attached to a host. at androidx.fragment.app.FragmentManager.enqueueAction 

At this moment, I am finding a solution to try, but I am expecting that if I clicked the edit button, a dialog will pop up.