java - just a quick thing about polymorphism -


say class classone extends classtwo, classone subclass , classtwo superclass. if went class , typed in: classtwo hello = new classone(); mean can use methods in classone have been inherited classtwo , not methods in classone? (e.g a. method called void eat(); in classtwo , classone inherited method void walk(); in classone , not in classtwo using hello keyword, access eat function , not walk function?), don't quite understand concept of polymorphism. can explain , giving example? much.

yes true, system see classone classtwo in regards available methods. think these concept buckets, in case classone fits classtwo bucket. if put classone in classtwo bucket can see classtwo bucket. pick out classone classtwo bucket, can cast it.

this helps in case of upcasting , downcasting, casting object supertype or subtype. either put item in basket(upcasting) or take out basket (downcasting).

this analogy might crap helps me :)

to answer question yes, can't make method-call method in classone if casted classtwo.

this handy anf many times preferable. think of interfaces, interface tells object provide set of methods. way can ensure these methods available calling object, contract object has it's surroundings.

also possible duplicate: try describe polymorphism easy can


Comments

Post a Comment

Popular posts from this blog

java.util.scanner - How to read and add only numbers to array from a text file -

i'm learning java , have question regarding reading file want read numbers file contains strings well. here example of file: 66.56 "3 java 3-43 5-42 2.1 1 and here coding: public class test { public static void main (string [] args){ if (0 < args.length) { file x = new file(args[0]); try{ scanner in = new scanner( new fileinputstream(x)); arraylist<double> test = new arraylist<>(); while(in.hasnext()){ if(in.hasnextdouble()){ double f=in.nextdouble(); test.add(f);} else {in.next();} } catch(ioexception e) { system.err.println("exception during reading: " + e); } } my problem add 66.56,2.1 , 1 doesn't add 3 after "3 or ignores 3-43 , 5-42 can tell me how skip strings , add doubles here? thanks all said 3 ie; "3, 3-43 , 4-42 strings either u read string , split , check number @ " , - or put in space between characters , integers. jvm after compilation tre...
Read more

rewrite - Trouble with Wordpress multiple custom querystrings -

i'm working on adding multiple querystring , doesn't seem work. i've found codes seems work others might i'm missing something. i want like: http://mydomain.com/board/?getyear=2013&getsometext2=sometext to http://mydomain.com/board/2013/sometext/ i added code below functions.php file. doesn't seem work should though. this works. echoing querystring gets both variable without problem. http://mydomain.com/board/2013/sometext/ but doesn't. tested querystring vis isset() seems nothing being set/get http://mydomain.com/board/2013/ function add_query_vars($vars) { $vars[] = "getyear"; $vars[] = "getsometext2"; return $vars; } add_filter('query_vars', 'add_query_vars'); function add_rewrite_rules($arules) { $anewrules = array('board/([^/]+)/([^/]+)/?$' => 'index.php?pagename=board&getyear=$matches[1]&getsometext2=$matches[2]'); $arules = $a...
Read more