Q. Can we declare an object as final?

final variables cannot be changed.
final methods cannot be overridden.
final classes cannot be inherited. However, there is something easily to be confused. There is no final Object in Java. You cannot even declare an Object in Java, only Object references. We only can have final object reference, which cannot be changed. It is like that the address of your house cannot be changed if it is declared as final. However, you can remodel your house, add a room, etc. Your house is not final, but the reference to your house is final. That is a little confusing. By the way, use finals as much as possible, but do not overuse them of course. It is because compiler knows they are not going to change, the byte code generated for them will be much more efficient.