Upcasting is the typecasting of a child object to a niam txiv khoom. Upcasting tuaj yeem ua tiav implicitly. Upcasting ua rau peb yooj yim nkag mus rau cov niam txiv hauv chav kawm tab sis nws tsis tuaj yeem nkag mus rau txhua tus menyuam hauv chav kawm siv qhov tshwj xeeb no.
Vim li cas peb thiaj xav tau Upcasting thiab downcasting hauv Java?
Vim li cas peb xav tau Upcasting thiab Downcasting? Hauv Java, peb tsis tshua siv Upcasting. Peb siv nws thaum peb xav tau los tsim cov cai uas cuam tshuam nrog tsuas yog cov niam txiv hauv chav kawm. Kev downcasting yog siv thaum peb xav tau los tsim cov cai uas nkag mus rau tus cwj pwm ntawm tus menyuam hauv chav kawm.
Kev siv Upcasting thiab downcasting yog dab tsi?
Up-casting yog casting rau supertype, thaum downcasting yog casting mus rau subtype. Upcasting thiab downcasting muab peb qhov zoo, xws li Polymorphism lossis pab pawg ntawm cov khoom sib txawv. Peb tuaj yeem kho ib yam khoom ntawm hom me nyuam hauv chav kawm kom ua tau raws li qhov khoom ntawm nws niam txiv chav kawm. Qhov no hu ua upcasting.
Qhov txawv ntawm Upcasting thiab downcasting yog dab tsi?
Upcasting (Generalization lossis Widening) yog casting rau niam txiv hom lus yooj yooj yim casting ib hom rau ib hom yog hu ua upcasting thaum downcasting (tshwj xeeb lossis nqaim) yog casting rau tus menyuam hom lossis casting hom hom rau tus kheej hom.
Dab tsi yog downcast thiab thaum twg nws yuav tsum tau?
Downcasting yog txheej txheem rov qab rau upcasting. Nws converts base class pointermus derived class pointer. Kev nqis tes yuav tsum ua manually. Nws txhais tau tias koj yuav tsum qhia meej meej typecast.
