How to Create Array of Objects in Java? - GeeksforGeeks

An Array of Objects is created using the Object class, and we know Object class is the root class of all Classes. We use the Class_Name followed ... 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ImproveArticle SaveArticle LikeArticle DifficultyLevel: BasicLastUpdated: 02Sep,2022ReadDiscussViewDiscussion ImproveArticle SaveArticle LikeArticle Prerequisite–DifferentwaystocreateobjectsinJavaJavaprogramminglanguageisallaboutclassesandobjectsasitisanobject-orientedprogramminglanguage.WhenwerequireasingleobjecttostoreinourprogramwedoitwithavariableoftypeObject.Butwhenwedealwithnumerousobjects,thenitispreferredtouseanArrayofObjects.ThearrayofObjectsthenameitselfsuggeststhatitstoresanarrayofobjects.UnlikethetraditionalarraystoresvalueslikeString,integer,Boolean,etcanArrayofObjectsstoresobjectsthatmeanobjectsarestoredaselementsofanarray.NotethatwhenwesayArrayofObjectsitisnottheobjectitselfthatisstoredinthearraybutthereferenceoftheobject.CreatinganArrayOfObjectsInJava–AnArrayofObjectsiscreatedusingtheObjectclass,andweknowObjectclassistherootclassofallClasses.WeusetheClass_Namefollowedbyasquarebracket[]thenobjectreferencenametocreateanArrayofObjects.Class_Name[]objectArrayReference;Alternatively,wecanalsodeclareanArrayofObjectsas:Class_NameobjectArrayReference[];BoththeabovedeclarationsimplythatobjectArrayReferenceisanarrayofobjects.Forexample,ifyouhaveaclassStudentthenwecancreateanarrayofStudentobjectsasgivenbelow:Student[]studentObjects; Or StudentstudentObjects[];Instantiatethearrayofobjects–Syntax: Class_Nameobj[]=newClass_Name[Array_Length];Forexample,ifyouhaveaclassStudent,andwewanttodeclareandinstantiateanarrayofStudentobjectswithtwoobjects/objectreferencesthenitwillbewrittenas: Student[]studentObjects=newStudent[2];Andonceanarrayofobjectsisinstantiatedlikethis,thentheindividualelementsofthearrayofobjectsneedstobecreatedusingthenewkeyword.ThebelowfigureshowsthestructureofanArrayofObjects:InitializingArrayOfObjects Oncethearrayofobjectsisinstantiated,weneedtoinitializeitwithvalues. Wecannotinitializethearrayinthewayweinitializewithprimitivetypesasitisdifferentfromanarrayofprimitivetypes.Inanarrayofobjects,wehavetoinitializeeachelementofarrayi.e.eachobject/objectreferenceneedstobeinitialized.Differentwaystoinitializethearrayofobjects:ByusingtheconstructorsByusingaseparatemembermethod1.Byusingtheconstructor:Atthetimeofcreatingactualobjects,wecanassigninitialvaluestoeachoftheobjectsbypassingvaluestotheconstructorseparately.Individualactualobjectsarecreatedwiththeirdistinctvalues.Thebelowprogramshowshowthearrayofobjectsisinitializedusingtheconstructor. Java//Javaprogramtodemonstrateinitializing//anarrayofobjectsusingconstructor classGFG{     publicstaticvoidmain(Stringargs[])    {         //Declaringanarrayofstudent        Student[]arr;         //Allocatingmemoryfor2objects        //oftypestudent        arr=newStudent[2];         //Initializingthefirstelement        //ofthearray        arr[0]=newStudent(1701289270,"Satyabrata");         //Initializingthesecondelement        //ofthearray        arr[1]=newStudent(1701289219,"OmmPrasad");         //Displayingthestudentdata        System.out.println(            "Studentdatainstudentarr0:");        arr[0].display();         System.out.println(            "Studentdatainstudentarr1:");        arr[1].display();    }} //Creatingastudentclasswith//idandnameasaattributesclassStudent{     publicintid;    publicStringname;     //Studentclassconstructor    Student(intid,Stringname)    {        this.id=id;        this.name=name;    }     //display()methodtodisplay    //thestudentdata    publicvoiddisplay()    {        System.out.println("Studentidis:"+id+""                           +"andStudentnameis:"                           +name);        System.out.println();    }}OutputStudentdatainstudentarr0: Studentidis:1701289270andStudentnameis:Satyabrata Studentdatainstudentarr1: Studentidis:1701289219andStudentnameis:OmmPrasad2.Byusingaseparatemembermethod:Byusingaseparatemembermethodalsowecaninitializeobjects.Amemberfunctionoftherespectiveclassiscreatedandthatisusedtoassigntheinitialvaluestotheobjects.Thebelowprogramshowshowthearrayofobjectsisinitializedusingaseparatemembermethod.Java//Javaprogramtodemonstrateinitializing//anarrayofobjectsusingamethod classGFG{     publicstaticvoidmain(Stringargs[])    {         //Declaringanarrayofstudent        Student[]arr;         //Allocatingmemoryfor2objects        //oftypestudent        arr=newStudent[2];         //Creatingactualstudentobjects        arr[0]=newStudent();        arr[1]=newStudent();         //Assigningdatatostudentobjects        arr[0].setData(1701289270,"Satyabrata");        arr[1].setData(1701289219,"OmmPrasad");         //Displayingthestudentdata        System.out.println(            "Studentdatainstudentarr0:");        arr[0].display();         System.out.println(            "Studentdatainstudentarr1:");        arr[1].display();    }} //CreatingaStudentclasswith//idandnameasaattributesclassStudent{     publicintid;    publicStringname;     //Methodtosetthedatato    //studentobjects    publicvoidsetData(intid,Stringname)    {        this.id=id;        this.name=name;    }     //display()methodtodisplay    //thestudentdata    publicvoiddisplay()    {        System.out.println("Studentidis:"+id+""                           +"andStudentnameis:"                           +name);        System.out.println();    }}OutputStudentdatainstudentarr0: Studentidis:1701289270andStudentnameis:Satyabrata Studentdatainstudentarr1: Studentidis:1701289219andStudentnameis:OmmPrasadLet’sseeanotherexamplewhereanArrayofObjectsisdeclaredwithInitialValues:Heredeclarationofanarrayofobjectsisdonebyaddinginitialvalues.Java//Javaprogramtodemonstrateanarray//ofobjectsisdeclaredwithinitialvalues. classGFG{     publicstaticvoidmain(Stringargs[])    {        //Creatinganarrayofobjects        //declaredwithinitialvalues        Object[]javaObjectArray            ={"Maruti",newInteger(2019),"Suzuki",                newInteger(2019)};       //Printingthevalues        System.out.println(javaObjectArray[0]);        System.out.println(javaObjectArray[1]);        System.out.println(javaObjectArray[2]);        System.out.println(javaObjectArray[3]);    }}OutputMaruti 2019 Suzuki 2019MyPersonalNotes arrow_drop_upSave LikeNext ArraysinJavaRecommendedArticlesPage:20,Dec2022,May1713,Nov1725,Sep1430,Jan1622,Mar1718,Feb1806,Jun1811,Sep1803,Oct1809,Nov1810,Dec2016,Nov2006,Dec2016,Dec2002,Jan2102,Jan2116,Dec2028,Dec2028,Dec2002,Jan2102,Jan2105,Jan2102,Jan21ArticleContributedBy:Satyabrata_Jena@Satyabrata_JenaVotefordifficultyCurrentdifficulty: BasicEasy Normal Medium Hard ExpertImprovedBy:mitalibhola94ArticleTags:Java-ArraysJavaPracticeTags:JavaReportIssueWritingcodeincomment? 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