Question

2.Discuss the two major benefits of using an interface and when would you use an abstract class in preference to an interface? Explain using examples

Answer 1

Answer:

Interface iis ian iindispensable imechanism iof iObject iOriented iprogramming. i iThe ireason iis ithat iinterface iallows iyou idescribe ithe icommunication icontract ibetween iobjects, iwhile iwith iclasses iyou idescribe inot ionly ithe icontract ibut ialso ia ibehavior. iSo iinterfaces icome iinto iplay ias isoon ias iyou ihave iobjects iwith ithe isame imethods iwhile ithey ihave inothing icommon iin itheir ibehavior iand ithis isituation iis imuch imost icommon irather ithan isituation iwhen iyou ihave ito iextend isome iclass.

One iof ithe ibenifits iof iusing iinterface iis ithat, ihere iimplementation idetail ican ibe ihidden ifrom ithe iuser, iless iconfusions iand ieasy iswapping ibetween iimplementations.

It iis ieasier ito imaintain ibackward icompatibility iand ikeeps ithe ilegacy iinterface iworking iwhile ibuilding inew iones.

iAbstract iclasses imay iprovide imembers ithat ihave ialready ibeen iimplemented. iTherefore, iyou ican iensure ia icertain iamount iof iidentical ifunctionality iwith ian iabstract iclass, ibut icannot iwith ian iinterface.

• If iyou ianticipate icreating imultiple iversions iof iyour icomponent, icreate ian iabstract iclass. iAbstract iclasses iprovide ia isimple iand ieasy iway ito iversion iyour icomponents. iBy iupdating ithe ibase iclass, iall iinheriting iclasses iare iautomatically iupdated iwith ithe ichange. iInterfaces, ion ithe iother ihand, icannot ibe ichanged ionce icreated iin ithat iway. iIf ia inew iversion iof ian iinterface iis irequired, iyou imust icreate ia iwhole inew iinterface.
• If ithe ifunctionality iyou iare icreating iwill ibe iuseful iacross ia iwide irange iof idisparate iobjects, iuse ian iinterface. iAbstract iclasses ishould ibe iused iprimarily ifor iobjects ithat iare iclosely irelated, iwhereas iinterfaces iare ibest isuited ifor iproviding icommon ifunctionality ito iunrelated iclasses.
• If iyou iare idesigning ismall, iconcise ibits iof ifunctionality, iuse iinterfaces. iIf iyou iare idesigning ilarge ifunctional iunits, iuse ian iabstract iclass.
• If iyou iwant ito iprovide icommon, iimplemented ifunctionality iamong iall iimplementations iof iyour icomponent, iuse ian iabstract iclass. iAbstract iclasses iallow iyou ito ipartially iimplement iyour iclass, iwhereas iinterfaces icontain ino iimplementation ifor iany imembers.

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