It's good coding practice to restrict mutability. As the instance variables are never changed we can make them immutable. Even better: Thus the whole class Dinglemouse becomes immutable - an instance of Dinglemouse can never be changed after initialization. As for the parameters it might not be mandatory to declare them final, but I made it a habit to declare all variables final by default, unless for the rare occasion where I really need a mutable variable. Also it is best avoided to change the value of parameters, so declaring them final makes this more explicit.

Excuse me. why use final in this case?

Thank you very much！

Could someone please tell me what kind of process is going on inside?