ArraysStrings = Char SequencesOther Sequences as Predefined TypesSequences of Programmer-Defined TypeOther Sequences as Array TypesInitializing Array DeclarationsInitializing Array DeclarationArray OperationsArray Types have Variable-SizeUninitializing Array DeclarationArray Elements UninitializedObject Array Elements UninitializedUninitialized Array Vs ElementExamplegetStrings()print()main()Slide 18Variable-Size CollectionSlide 20Slide 21Special TypeSupporting EncapsulationHistoryImplementing a HistoryUsing a HistoryPrinting a HistoryDatabaseSlide 29deleteElement (String element)Slide 31Multi-element windowSlide 33indexOf (String element)Slide 35public boolean member(String element)public void clear()Slide 38addElement(“Mary Doe”)Logical but not Physical ExtensionsSlide 41Physical and Logical ExtensionsExtending an InterfaceExtending a ClassPhysical and Computer InheritanceNo Explicit ExtensionEquivalent Class DefinitionSome Methods of Class ObjectIS-A RelationshipsIS-A & PolymorphismSlide 51Assignment Rules for Primitive TypesAssignment Rules for Object TypesIS-A DefinitionType Checking ExamplesGetting an UpgradeGetting a DowngradeSlide 58Slide 59Slide 60SetOverriding Inherited MethodsOverriding addElement()superOmitting SuperMore OverridingSlide 67Motivation for SwitchMain with SwitchMulti-case armsOmitting breakIllegal SwitchOrdinal TypeArrays•Arrays–Collections (Set, Database, History)•Inheritance–inheriting ancestor’s traits–inheriting benefactor’s assets–inheriting instance members( methods/variables)•IS-A Relationship–human IS-A Mammal–salmon IS-A Fish–“Joe Doe” IS-A Student–ALoan IS-A LoanStrings = Char SequencesJ o h n F . K e n n d yeh e l l oString {sequences of characters}1 4 3 l 0Other Sequences as Predefined Types100 98 99 100 9060 40 50{sequences of integers}80JFK FDR{sequence of Strings}JC BC RR GB3.8 3.1{sequences of doubles}3.7 3.1 3.6 3.9IntSequenceDoubleSequenceStringSequenceSequences of Programmer-Defined Typeloan1 loan2{sequence of loans}loan3temperature1{sequence of temperatures}temperature2 temperature3temperature1 temperature2TemperatureSequenceLoanSequenceLoan[]Temperature[]Array TypesArraysArray ElementOther Sequences as Array Types100 98 99 100 9060 40 50{sequences of integers}80{sequence of strings}3.8 3.1{sequences of doubles}3.7 3.1 3.6 3.9int[]double[]String[]JFK FDR JC BC RR GBInitializing Array Declarations100 98 99 100 90 80int[] assignmentScores = {100, 98, 99, 80};3.8 3.1 3.7 3.1 3.6 3.9double[] gpas = {3.8, 3.1, 3.7, 3.1, 3.6, 3.9};String[] initials = {“JFK”, “FDR”, “JC”, “BC”, “GW”, “WW”}; JFK FDR JC BC GW WWassignmentScoresArray TypeElement TypeArray LiteralArray VariableInitializing Array Declaration<ElementType> [] <arrayVariable> = {<element1>, …, <elementN>}Loan [] loans = {new ALoan(100000), new AnotherLoan (100)};Array OperationsString[] initials = {“JFK”, “FDR”, “JC”, “BC”, “GW”, “WW”}; JFK FDR JC BC GW WWinitials.length  6initials[0]initials[initials.length - 1]initials[initials.length]  ArrayIndexOutOfBoundsExceptionpublic named constantinitials[0] = “HT”HTinitials[initials.length] = “HT”  ArrayIndexOutOfBoundsExceptionArray Instance Size FixedArray Types have Variable-Size100 98 99 100 9060 40 5080int[]100 98 99 100 90 80int[] assignmentScores = {100, 98, 99, 100, 99, 80};assignmentScoresassignmentScores = {60, 40, 50};assignmentScores60 40 50Uninitializing Array Declarationint[] assignmentScores;assignmentScoresnullassignmentScores = {60, 40, 50};assignmentScores60 40 50Array Elements Uninitializedint[] assignmentScores = new int[3];assignmentScores0 0 0Object Array Elements UninitializedString[] initials = new String[3];initialsnullnull nullUninitialized Array Vs ElementString[] initials = new String[3];initialsnullnull nullString[] initials;initialsnullinitials[0] nullinitials[0]initials[0].charAt(0)  StringIndexOutOfBounds ArrayIndexOutOfBoundsExceptionExamplegetStrings()static String[] getStrings() { System.out.println("Number of Strings:"); int numElements = Keyboard.readInt(); System.out.println("Please enter " + numElements + " strings"); String[] strings = new String[numElements]; for (int elementNum = 0; elementNum < numElements; elementNum++) strings[elementNum] = Keyboard.readLine(); return strings;}variableprint()static void print(String[] strings) { System.out.println("******************"); for ( int elementNum = 0; elementNum < strings.length; elementNum++) System.out.println(strings[elementNum]); System.out.println("******************");}String array of arbitrary dimension (size)main()public static void main(String[] args){ String[] names = getStrings(); while (true) { String command = Keyboard.readLine(); if (command.length > 0 && command.charAt(0) == 'q') break; if (command.length > 0 && command.charAt(0) == 'p') print(names); } }main()Variable-Size Collectionfilled partunfilled partcurrent sizemaximum size3James DeanJoe DoeJane Smithsize arrayVariable-Size Collectionfilled partunfilled partcurrent sizemaximum sizeVariable-Size Collectionpublic class <ClassNeedingVariableSizeCollection> { …final static int A_MAX_SIZE = 50;String[] a = new String [MAX_SIZE];int aSize = 0;…//process afor (int index = 0; index < aSize; index++) System.out.println(a[index]);…final int B_MAX_SIZE = 50;String[] b = new String [MAX_SIZE];int bSize = 0; //process b …}Special Typepublic class <ClassNeedingVariableSizeCollection> { ... AVariableSizeCollection a = new AVariableSizeCollection(); ... for (int index = 0; index < a.size; index++) System.out.println(a.contents[index]); … AVariableSizeCollection b = new AVariableSizeCollection(); ...}public class AVariableSizeCollection {public static final int MAX_SIZE = 50;public String[] contents = new String [MAX_SIZE];public int size = 0;}No encapsulation!a.contents[a.size] = Keyboard.readString();Size not updatedSupporting Encapsulationpublic interface …. {public static final int MAX_SIZE = 50;}public void addElement (String element);public void print ();Implementation specificUser specificHistorypublic interface StringHistory {}public void addElement (String element);public int size();public String elementAt (int index);Implementing a Historypublic class AStringHistory