In reply to Ayush:
The UVM is a phased approach. You have certain phases which are executes in a well-defined order. In the build_phase all components of your UVM testbenbch will be constructed. This goes topdown. In the connect_phase all components will be connected. This goes bottom-up. new() is the constructor whic is needed by each class. Ther4 is no new_phase in the UVM.