How to Sort Wrapper class Collection in Apex - Jitendra Zaa

How to Sort Wrapper class Collection in Apex · Comparable Interface: To implement the Comparable Interface, you must declare global class with ... Skiptocontent ThereisinbuiltfunctionalityinApextosorttheprimitivedatatypessupportedbyforce.com.Iamsuremaximumofdevelopersmusthavecomeacrossthesituationswheretheyneedtosortcustomdatatypebuiltbythemi.e.customclassorIwouldsaywrapperclassintermsofforce.com. Butthink,Howforce.comwillcometoknowthathowtosortclass?Incaseofinteger,dateordoubletheyalreadyknow.Buthowtheyaregoingtoknowthatwhatisgoingtobecontentinyourclass?BeforeSummer’12therewasnodirectway.HoweverthankstoSalesforcetointroducetheinterfaceComparableinSummer’12release.And…thereissmileonthefaceofJavadevelopers,becausetheyalreadyknowwhatitis. Solet’sstartwith“WhatistheuseofinterfaceComparable?“Iwouldsay,thisisthewaytotellforce.comthathowwearegoingtocomparethecustomObjects(Wrapperclass). ComparableInterface: ToimplementtheComparableInterface,youmustdeclareglobalclasswiththeimplementskeywordasfollow: globalclassBookimplementsComparable Now,yourclassmustimplementthemethod“compareTo“asfollow: globalIntegercompareTo(ObjectobjToCompare) { //Yourcodetoimplementlogic } compareTo()method: ThecompareTo()methodmustreturnfollowingintegervalue 0ifbothobjectisequal >0iftheinstanceobjectisgreaterthan“objToCompare” <0iftheinstanceobjectissmallerthan“objToCompare” Samplecode Let’staketheexampleofclass“Book”,whichhavefollowingdatamembers, BookTitle–String Author–String TotalPages–Integer Price–Double globalclassBookimplementsComparable{ publicStringBookTitle; publicStringAuthor; publicIntegerTotalPages; publicDoublePrice; publicDatepublishingDate; publicenumSORT_BY{ ByTitle,ByPage } //Variabletodecidethememberonwhichsortingshouldbeperformed publicstaticSORT_BYsortBy=SORT_BY.ByTitle; publicBook(Stringbt,Stringa,Integertp,Doublep,Datepd) { BookTitle=bt; Author=a; TotalPages=tp; Price=p; publishingDate=pd; } globalIntegercompareTo(ObjectobjToCompare){ //SortbyBookNameAlphabetically if(sortBy==SORT_BY.ByTitle) { returnBookTitle.compareTo(((Book)objToCompare).BookTitle); } else//SortbyBookprice { returnInteger.valueOf(Price-((Book)objToCompare).Price); } } } Asyoucanseeinabovecode,wearesortingonthebasisofeitherBookTitleorPrice.Thelogiccanbeanythingdependingonbusinessrequirement. RunningthesamplecodeinDeveloperConsole: Runbelowcodein“DeveloperConsole”frombrowseror“ExecuteAnonymous”fromEclipse. Book[]books=newBook[]{ newBook('SalesforceHandbook','JeffDouglas',360,35,Date.newInstance(2011,03,20)), newBook('LetUsC','YashavantP.Kanetkar',593,58,Date.newInstance(2008,03,21)), newBook('HeadFirstDesignPatterns','ElisabethFreeman',678,28,Date.newInstance(2004,11,01)) }; Book.sortBy=Book.SORT_BY.ByTitle; books.sort(); System.debug(books); Book.sortBy=Book.SORT_BY.ByPrice; books.sort(); System.debug(books); Whenyouwillseetheoutput,firsttimeitsortedbyBookTitleandsecondtimeitissortedaccordingPrice. Ihopethispostwillbehelpfultomanysalesforcedevelopers. Happycoding!!! SharethispostClicktoemailthistoafriend(Opensinnewwindow)ClicktoshareonTwitter(Opensinnewwindow)ClicktoshareonFacebook(Opensinnewwindow)ClicktoshareonLinkedIn(Opensinnewwindow)ClicktoshareonPinterest(Opensinnewwindow)ClicktoshareonTumblr(Opensinnewwindow)ClicktoshareonReddit(Opensinnewwindow)ClicktoshareonPocket(Opensinnewwindow) 14comments Hi,IamnotabletounderstandhowisthemethodreturningcompareToresults? Reply Hi,Forstringwealreadyhavecomparetomethodswhichreturnseither0,1.Incaseofintegerswearehandlingthosevaluebyourselfonly. Reply doesanybodytriedtocover100%ofthissamplecodewhiletesting? Reply Thisarticleisverynice Reply Thankyouforthis,itisveryuseful.Anychancetopickyourbrainonhowtosortbytwowrapperproperties?sofirstBookTitle,thenBookPrice…anycommentswouldbeappreciated. Reply Thanksdude.Itisgoodpeaceofcode. Reply Isthereanywaythatwecanspecifysortingorderlikeascendingordescendingorder? Reply Yes, Itsuptoyouhowyoureturnthevalueinmethod“compareTo”. Justchangethelogicandgo.. Reply HiJitendra, Canupleaseguideme…Ihavefollowedthestepsforwrappersortinganditsworkinggreatinatabledoen’thaveanynullvalues…butinmytablehavingnullvaluesforfewcolumnsthenitsgivingerrors…Pleaseseemypieceofcode. globalwithsharingclassActivitiesCollectionimplementsComparable{ publicstringtype{get;set;} } publicenumSORT_BY{ ByType } publicenumOrder_By{ ascend,descend } globalintegercompareTo(ObjectobjToCompare){ if(typo!=null&&typo!=”&&type!=null&&type!=”&&sortBy==SORT_BY.ByType&&orderBy==Order_BY.ascend) returntype.compareTo(typo); elseif(typo!=null&&typo!=”&&type!=null&&type!=”&&typo!=‘–None–‘&&sortBy==SORT_BY.ByType&&orderBy==Order_BY.descend) } returntypo.compareTo(type); } Pleasehelpme. Reply Hi, Abovecodeisnotcomplete.Whatistypoandhowyouarecomparingobject“objToCompare”? Pleasepostcompletecode. Reply cananyonewillpleasedothisVFpagecontroller,ifanyquestionpleaseaskmeaboutthisVFpage Reply Howcanthisbechangedtodescendingorder? Reply whatifIwanttocomparebybothi.e1stpriceandthenname Reply Howthedatecomparetoisgoingtoworkhere,letssayifiwanttocomparebypublishingDate? Reply LeaveacommentCancelreplyYouremailaddresswillnotbepublished.Requiredfieldsaremarked*CommentName* Email* Website Notifymeoffollow-upcommentsbyemail.Notifymeofnewpostsbyemail. Δ ThissiteusesAkismettoreducespam.Learnhowyourcommentdataisprocessed. Postnavigation PreviouspostSalesforceInterviewQuestions–Part10NextpostSalesforceInterviewQuestions–Part11 SearchBlogContent SubscribetoBlogviaEmail Nevermissapost.Provideyouremailaddresstogetlatestblogposts,rightintoyouremailbox. 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