{"id":34855,"date":"2019-10-31T22:00:51","date_gmt":"2019-10-31T19:00:51","guid":{"rendered":"https:\/\/prohoster.info\/blog\/10-printsipov-obektno-orientirovannogo-programmirovaniya-o-kotoryh-dolzhen-znat-kazhdyj-razrabotchik\/"},"modified":"2019-10-31T22:00:51","modified_gmt":"2019-10-31T19:00:51","slug":"10-printsipov-obektno-orientirovannogo-programmirovaniya-o-kotoryh-dolzhen-znat-kazhdyj-razrabotchik","status":"publish","type":"post","link":"https:\/\/prohoster.info\/sq\/blog\/novosti-interneta\/10-printsipov-obektno-orientirovannogo-programmirovaniya-o-kotoryh-dolzhen-znat-kazhdyj-razrabotchik","title":{"rendered":"10 parimet e programimit objektiv q\u00eb \u00e7do zhvillues duhet t\u00eb dij\u00eb","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

\"10
\n
\nM\u00eb shpesh has zhvillues q\u00eb nuk kan\u00eb d\u00ebgjuar p\u00ebr parimet SOLID (ne kemi folur holl\u00ebsisht p\u00ebr to k\u00ebtu<\/a><\/noindex>. \u2014 P.S.) ose programimin orientuar n\u00eb objekte (OOP), ose kan\u00eb d\u00ebgjuar, por nuk i p\u00ebrdorin ato n\u00eb praktik\u00eb. Ky artikull shkruan p\u00ebr p\u00ebrfitimet e parimeve OOP q\u00eb ndihmojn\u00eb zhvilluesin n\u00eb pun\u00ebn e tij t\u00eb p\u00ebrditshme. Disa nga ato jan\u00eb mjaft t\u00eb njohura, t\u00eb tjera - jo aq shum\u00eb, k\u00ebshtu q\u00eb artikulli do t\u00eb jet\u00eb i dobish\u00ebm si p\u00ebr fillestar\u00ebt ashtu edhe p\u00ebr programuesit me p\u00ebrvoj\u00eb.
\n<\/a><\/noindex><\/p>\n

Kujtojm\u00eb:<\/b> p\u00ebr t\u00eb gjith\u00eb lexuesit e \u201cHabr\u201d - nj\u00eb zbritje prej 10,000 rubla p\u00ebr regjistrimin n\u00eb \u00e7do kurs Skillbox me kodin promocional \u201cHabr\u201d.<\/i><\/p>\n

Skillbox rekomandon:<\/b> Kurs online edukativ Java-developer<\/a><\/noindex>.<\/p><\/blockquote>\n

<\/p>\n

DRY (Mos e p\u00ebrs\u00ebris veten)<\/h3>\n

\nNj\u00eb parim mjaft i thjesht\u00eb, thelbi i t\u00eb cilit \u00ebsht\u00eb i qart\u00eb nga emri: \u00abMos u p\u00ebrs\u00ebrit\u00bb. P\u00ebr nj\u00eb programues, kjo do t\u00eb thot\u00eb nevoja p\u00ebr t\u00eb shmangur kodin e p\u00ebrs\u00ebritur, si dhe mund\u00ebsin\u00eb p\u00ebr t\u00eb p\u00ebrdorur abstraksionin n\u00eb pun\u00ebn e tij.<\/p>\n

N\u00ebse ka dy segmente t\u00eb p\u00ebrs\u00ebritura n\u00eb kod, ato duhet t\u00eb bashkohen n\u00eb nj\u00eb metod\u00eb. N\u00ebse nj\u00eb vler\u00eb e caktuar \u00ebsht\u00eb p\u00ebrdorur m\u00eb shum\u00eb se nj\u00eb her\u00eb, ajo duhet t\u00eb konvertohet n\u00eb nj\u00eb konstante publike.<\/p>\n

Kjo \u00ebsht\u00eb e nevojshme p\u00ebr t\u00eb thjeshtuar kodin dhe p\u00ebr t\u00eb leht\u00ebsuar mb\u00ebshtetje, q\u00eb \u00ebsht\u00eb q\u00ebllimi kryesor i OOP. Nuk duhet t\u00eb abuzohet me bashkimin gjithashtu, pasi e nj\u00ebjta kod nuk do t\u00eb kaloj\u00eb verifikimin si me OrderId ashtu edhe me SSN.<\/p>\n

Inkapcizimi i ndryshimeve<\/h3>\n

\nProduktet software t\u00eb shumic\u00ebs s\u00eb kompanive vazhdojn\u00eb t\u00eb zhvillohen. K\u00ebshtu, n\u00eb kodin duhet b\u00ebr\u00eb ndryshime, ai duhet mb\u00ebshtetur. Mund t\u00eb thjeshtoni jet\u00ebn tuaj duke e p\u00ebrdorur inkapsulimin. Kjo do t\u00eb lejoj\u00eb q\u00eb baza ekzistuese e kodit t\u00eb testohet dhe mb\u00ebshtetet m\u00eb efikas. Ja nj\u00eb nga shembujt<\/a><\/noindex>.<\/p>\n

N\u00ebse shkruani n\u00eb Java, at\u00ebher\u00eb p\u00ebr parazgjedhje jepni metodat e privatin dhe variablat<\/a><\/noindex>.<\/p>\n

Parimi i hapjes\/mbylljes<\/h3>\n

\nKy parim mund t\u00eb mbahet leht\u00eb mend n\u00ebse lexoni deklarat\u00ebn e m\u00ebposhtme: \u00abEntitetet software (klasat, modulat, funksionet, etj.) duhet t\u00eb jen\u00eb t\u00eb hapura p\u00ebr zgjerim, por t\u00eb mbyllura p\u00ebr ndryshim\u00bb. N\u00eb praktik\u00eb kjo do t\u00eb thot\u00eb se ato mund t\u00eb lejojn\u00eb t\u00eb ndryshojn\u00eb sjelljen e tyre pa ndryshuar kodin burimor.<\/p>\n

Ky parim \u00ebsht\u00eb i r\u00ebnd\u00ebsish\u00ebm kur ndryshimet n\u00eb kodin burimor k\u00ebrkojn\u00eb shqyrtimin e tij, testimin modular dhe procedura t\u00eb tjera. Kodi q\u00eb i n\u00ebnshtrohet parimit t\u00eb hapjes\/mbylljes nuk ndryshohet gjat\u00eb zgjerimit, prandaj ka shum\u00eb m\u00eb pak probleme me t\u00eb.<\/p>\n

Ky \u00ebsht\u00eb nj\u00eb shembull kodi q\u00eb shkel k\u00ebt\u00eb parim.<\/p>\n

\"10
\n
\nN\u00ebse n\u00eb t\u00eb duhet t\u00eb b\u00ebni ndonj\u00eb ndryshim, do t\u00eb nevojitet shum\u00eb koh\u00eb, pasi do t\u00eb duhet t\u00eb ndryshoni t\u00eb gjitha pjes\u00ebt e kodit q\u00eb kan\u00eb lidhje me fragmentin e nevojsh\u00ebm.<\/p>\n

A propos, hapja-mbyllja \u00ebsht\u00eb nj\u00eb nga parimet SOLID.<\/p>\n

Parimi i p\u00ebrgjegj\u00ebsis\u00eb s\u00eb vetme (SRP)<\/h3>\n

\nNj\u00eb tjet\u00ebr parim nga grupi SOLID. Ai thot\u00eb se \u00abka vet\u00ebm nj\u00eb arsye q\u00eb \u00e7on n\u00eb ndryshimin e nj\u00eb klase\u00bb. Klasa zgjidh vet\u00ebm nj\u00eb problem. Ajo mund t\u00eb ket\u00eb disa metoda, por \u00e7do nj\u00ebra p\u00ebrdoret vet\u00ebm p\u00ebr t\u00eb zgjidhur problemin e p\u00ebrgjithsh\u00ebm. T\u00eb gjitha metodat dhe pron\u00ebsit\u00eb duhet t\u00eb sh\u00ebrbejn\u00eb vet\u00ebm p\u00ebr k\u00ebt\u00eb. <\/p>\n

\"10
\n
\nVlera e k\u00ebtij parimi q\u00ebndron n\u00eb at\u00eb se ai dob\u00ebson lidhjen midis komponentit t\u00eb ve\u00e7ant\u00eb t\u00eb softuerit dhe kodit. N\u00ebse shtoni m\u00eb shum\u00eb se nj\u00eb funksionalitet n\u00eb nj\u00eb klas\u00eb, kjo vendos nj\u00eb lidhje midis dy funksioneve. K\u00ebshtu, n\u00ebse ndryshoni nj\u00eb prej tyre, ka nj\u00eb mund\u00ebsi t\u00eb madhe q\u00eb t\u00eb d\u00ebmtoni tjetr\u00ebn, lidhur me t\u00eb par\u00ebn. Dhe kjo do t\u00eb thot\u00eb rritjen e cikleve t\u00eb testimit p\u00ebr t\u00eb identifikuar problemet paraprakisht.<\/p>\n

Parimi i opsionit t\u00eb var\u00ebsis\u00eb (DIP)<\/h3>\n

\n\"10
\n
\nM\u00eb lart kemi dh\u00ebn\u00eb nj\u00eb shembull kode ku AppManager varet nga EventLogWriter, i cili nga ana e tij \u00ebsht\u00eb i lidhur ngusht\u00eb me AppManager. N\u00ebse k\u00ebrkohet nj\u00eb m\u00ebnyr\u00eb tjet\u00ebr p\u00ebr t\u00eb treguar njoftimin, qoft\u00eb kjo njoftim push, SMS ose email, duhet t\u00eb ndryshoni klas\u00ebn AppManager.<\/p>\n

Problemi mund t\u00eb zgjidhet duke p\u00ebrdorur DIP. N\u00eb vend t\u00eb AppManager, ne k\u00ebrkojm\u00eb EventLogWriter, i cili do t\u00eb introdukohet n\u00ebp\u00ebrmjet framework-ut.<\/p>\n

DIP ofron mund\u00ebsin\u00eb p\u00ebr t\u00eb z\u00ebvend\u00ebsuar module t\u00eb ve\u00e7anta me t\u00eb tjera, duke ndryshuar modulimin e var\u00ebsis\u00eb. Kjo lejon ndryshimin e nj\u00eb moduli pa ndikuar n\u00eb t\u00eb tjer\u00ebt.<\/p>\n

Kompozimi n\u00eb vend t\u00eb trash\u00ebgimis\u00eb<\/h3>\n

\n\"10Ka dy m\u00ebnyra kryesore p\u00ebr t\u00eb rip\u00ebrdorur kodin - trash\u00ebgimi dhe kompozim, dhe secila ka avantazhet dhe disavantazhet e saj. Zakonisht preferohet e dyta, pasi \u00ebsht\u00eb m\u00eb fleksibile.<\/p>\n

Kompozimi ofron mund\u00ebsin\u00eb p\u00ebr t\u00eb ndryshuar sjelljen e klas\u00ebs gjat\u00eb ekzekutimit duke vendosur pron\u00ebsit\u00eb e saj. Kur implementohen nd\u00ebrfaqet, p\u00ebrdoret polimorfizmi, i cili ofron nj\u00eb implementim m\u00eb fleksib\u00ebl.<\/p>\n

Madje \u201cEffective Java\u201d i Joshua Bloch k\u00ebshillon q\u00eb t'i jepet p\u00ebrpar\u00ebsi kompozimit n\u00eb vend t\u00eb trash\u00ebgimis\u00eb.<\/p>\n

Parimi i z\u00ebvend\u00ebsimit t\u00eb Barbara Liskov (LSP)<\/h3>\n

\nNj\u00eb tjet\u00ebr parim nga mjeti SOLID. Ai thot\u00eb se n\u00ebnklasat duhet t\u00eb jen\u00eb t\u00eb z\u00ebvend\u00ebsueshme p\u00ebr superklas\u00ebn. K\u00ebshtu, metodat dhe funksionet q\u00eb punojn\u00eb me superklas\u00ebn duhet t\u00eb ken\u00eb mund\u00ebsin\u00eb t\u00eb punojn\u00eb pa probleme edhe me n\u00ebnklasat e saj.<\/p>\n

LSP \u00ebsht\u00eb i lidhur si me parimin e p\u00ebrgjegj\u00ebsis\u00eb s\u00eb vetme, ashtu edhe me parimin e ndarjes s\u00eb p\u00ebrgjegj\u00ebsis\u00eb. N\u00ebse nj\u00eb klas\u00eb ofron m\u00eb shum\u00eb funksionalitete se sa n\u00ebnklasa, at\u00ebher\u00eb kjo e fundit nuk do t\u00eb mb\u00ebshtes\u00eb disa funksione, duke shkelur k\u00ebt\u00eb parim.<\/p>\n

Ja nj\u00eb fragment kodi q\u00eb \u00ebsht\u00eb n\u00eb kund\u00ebrshtim me LSP.<\/p>\n

\"10
\n
\nMetoda area(Rectangle r) llogarit sip\u00ebrfaqen e Rectangle. Programi do t\u00eb bjer\u00eb pas ekzekutimit t\u00eb Square, sepse Square k\u00ebtu nuk \u00ebsht\u00eb nj\u00eb Rectangle. Sipas parimit LSP, funksionet q\u00eb p\u00ebrdorin referenca n\u00eb klasat baz\u00eb duhet t\u00eb jen\u00eb n\u00eb gjendje t\u00eb p\u00ebrdorin edhe objektet e klasave t\u00eb derivuara pa udh\u00ebzime shtes\u00eb.<\/p>\n

Ky parim, i cili \u00ebsht\u00eb nj\u00eb definicion specifik i n\u00ebnklas\u00ebs, u propozua nga Barbara Liskov n\u00eb vitin 1987 n\u00eb nj\u00eb konferenc\u00eb n\u00eb nj\u00eb fjalim kryesor me titull \"Abstraksioni e t\u00eb dh\u00ebnave dhe hierarkia\" \u2014 nga k\u00ebtu dhe emri i tij.<\/p>\n

Parimi i ndarjes s\u00eb interfes\u00ebs (ISP)<\/h3>\n

\nNj\u00eb parim tjet\u00ebr SOLID. Sipas tij, nj\u00eb interfes\u00eb q\u00eb nuk p\u00ebrdoret nuk duhet t\u00eb zbatohet. Ndjekja e k\u00ebtij parimi ndihmon sistemin t\u00eb mbetet fleksib\u00ebl dhe i p\u00ebrshtatsh\u00ebm p\u00ebr rifaktorizim kur ndryshohet logjika e pun\u00ebs.<\/p>\n

Kjo situat\u00eb ndodh shpesh kur interfesa p\u00ebrmban disa funksionalitete, dhe klienti ka nevoj\u00eb vet\u00ebm p\u00ebr nj\u00eb prej tyre.<\/p>\n

Duke qen\u00eb se shkruhen interfesa \u00ebsht\u00eb nj\u00eb detyr\u00eb e v\u00ebshtir\u00eb, pas p\u00ebrfundimit t\u00eb pun\u00ebs, ta ndryshosh at\u00eb pa prishur di\u00e7ka, do t\u00eb jet\u00eb problem.<\/p>\n

Avantazhi i parimit ISP n\u00eb Java \u00ebsht\u00eb se fillimisht duhet t\u00eb zbatohen t\u00eb gjitha metodat, dhe vet\u00ebm pastaj ato mund t\u00eb p\u00ebrdoren nga klasat. Prandaj, ky parim ofron mund\u00ebsin\u00eb p\u00ebr t\u00eb reduktuar numrin e metodave.<\/p>\n

\"10
\n <\/p>\n

Programimi p\u00ebr interfes\u00ebn, dhe jo p\u00ebr zbatimin<\/h3>\n

\nK\u00ebtu gjith\u00e7ka \u00ebsht\u00eb e qart\u00eb nga emri. Rrjedhimi i k\u00ebtij parimi \u00e7on n\u00eb krijimin e kodit fleksib\u00ebl, i cili \u00ebsht\u00eb n\u00eb gjendje t\u00eb punoj\u00eb me \u00e7do zbatim t\u00eb ri t\u00eb interfes\u00ebs.<\/p>\n

Duhet t\u00eb p\u00ebrdoren tipa interfese p\u00ebr variablat, llojet e kthimit ose llojin e argjumentit t\u00eb metod\u00ebs. Nj\u00eb shembull \u2014 p\u00ebrdorimi i SuperClass, e jo SubClass.<\/p>\n

Pra:<\/p>\n

List numbers = getNumbers();<\/i><\/p>\n

Dhe jo:<\/p>\n

ArrayList numbers = getNumbers();<\/i><\/p>\n

Ja nj\u00eb zbatim praktik t\u00eb asaj q\u00eb \u00ebsht\u00eb th\u00ebn\u00eb m\u00eb sip\u00ebr.<\/p>\n

\"10
\n <\/p>\n

Parimi i delegimit<\/h3>\n

\nNj\u00eb shembull i zakonsh\u00ebm \u2014 metodat equals() dhe hashCode() n\u00eb Java. Kur \u00ebsht\u00eb e nevojshme t\u00eb krahasohen dy objekte, kjo veprim delegohet klas\u00ebs p\u00ebrkat\u00ebse n\u00eb vend t\u00eb klientit.<\/p>\n

Avantazhi i k\u00ebtij parimi \u00ebsht\u00eb se p\u00ebrjashtohet dublimi i kodit dhe ndryshimi i sjelljes \u00ebsht\u00eb relativisht i thjesht\u00eb. Ai gjithashtu aplikohet p\u00ebr delegimin e ngjarjeve.<\/p>\n

\"10
\n
\nT\u00eb gjith\u00eb k\u00ebta parime lejojn\u00eb shkruarjen e kodit m\u00eb fleksib\u00ebl, t\u00eb bukur dhe t\u00eb besuesh\u00ebm me lidhshm\u00ebri t\u00eb lart\u00eb dhe var\u00ebsis\u00eb t\u00eb ul\u00ebt. Sigurisht, teoria \u00ebsht\u00eb e mir\u00eb, por q\u00eb zhvilluesi t\u00eb v\u00ebrtet\u00eb t\u00eb filloj\u00eb ta p\u00ebrdor\u00eb njohurin\u00eb e fituar, nevojitet praktik\u00eb. Hapi tjet\u00ebr pas zot\u00ebrimit t\u00eb parimeve t\u00eb OOP mund t\u00eb jet\u00eb studimi i modeleve t\u00eb dizajnit p\u00ebr t\u00eb zgjidhur probleme t\u00eb zakonshme n\u00eb zhvillimin e softuerit.<\/p>\n

Skillbox rekomandon:<\/b><\/p>\n