How to avoid subclass without use of final Keyword in Java -

- 

final class abstest {}  class btest extends abstest {}

how prevent creation of subclass(es) without using final keyword?

here few options

  • create private constructor
  • make each method final, people can't override them. avoid accidental calling of methods subclass way. doesn't stop subclassing though.

  • put check constructor class:

    if (this.getclass() != abc.class) { throw new runtimeexception("subclasses not allowed"); }

but final is provided solve such problem must say, so better go with final!!!


Comments

Post a Comment

Popular posts from this blog

Fail to load namespace Spring Security http://www.springframework.org/security/tags -

-
i have problem namespace of spring security on xhtml page. don't understand why can't load uri, , have following issue: whitelabel error page application has no explicit mapping /error, seeing fallback. tue jul 21 16:58:12 utc 2015 there unexpected error (type=not found, status=404). please need help! possible uri has been changed? best regards you using incorrect namespace url. correct url http://www.springframework.org/schema/security the error page seeing spring source website since not recognize url. try visiting http://www.springsource.org/security/tags in browser update : spring security tags used in jsp page correct tag lib declaration is: <%@ taglib prefix="sec" uri="http://www.springframework.org/security/tags" %>
Read more

sql - MySQL query optimization using coalesce -

-
can explain me why second query faster first? (first 1 takes around 40 seconds, second 1 less 0.1) select releases.feature_code, releases.platform_id, version, release_date, general_available, uri, filesize, display_name, feature_name.full_name, if ((select exists(select 1 release_exceptions releases.feature_code = release_exceptions.feature_code , releases.platform_id = release_exceptions.platform_id , releases.version = release_exceptions.version) = 1), 1, 0) release_exceptions releases left outer join platform using(platform_id) left outer join feature_name using(feature_code) order version desc; ~~~ query 2 ------------------ ~~~ select feature_code, version, release_date, general_available, platform_id, uri, filesize, display_name, feature_name.full_name, coalesce(release_exceptions, 0) release_exceptions mus.releases left outer join ( select distinct feature_code, version, platform_id, 1 release_exceptions mus.release_exceptions ) release_exceptions using ...
Read more

unity3d - Unity local avoidance in user created world -

-
i'm using unity3d networked multiplayer online game have large complex 3d terrain scene forest, trees, cliff, hills, mountains, bounders, etc. players can build structures sort of minecraft, , put them anywhere in scene, or move them around anytime. aside human controlled players, there automated ai players , objects animals roaming around scene following path. the problem how make these automated ai players , animals, able navigate around static , dynamic player created structures, because path follow can blocked player created structures, or other players , other ai objects, cliffs etc. have find away around them or on track if tumble down off high cliff example. so made navmesh , used navagents, takes care of static, non moving objects, how make ai players navigate around each other , dynamic structures created players can number in hundreds? i thought of adding navmeshobstacle everything, result in being attached hundreds of objects since user created structures b...
Read more