Understanding Recursive Classes

Understanding Recursive Classes CMSC 150: Lecture 22

StringList: A Recursive Class public class StringList { // instance variables private booleanisEmpty; private String thisString; private StringListrestOfStringList; // constructors public StringList() { … } public StringList(StringnewString, StringListaList) { … } public String toString() { … } public String getLineStartingWith(String prefix) { … } }

StringList: A Recursive Class public class StringList { // instance variables private booleanisEmpty; private String thisString; private StringListrestOfStringList; // constructors public StringList() { … } public StringList(StringnewString, StringListaList) { … } • public String toString() { … } • public String getLineStartingWith(String prefix) { … } } Data

StringList: A Recursive Class public class StringList { // instance variables private booleanisEmpty; private String thisString; private StringListrestOfStringList; // constructors public StringList() { … } public StringList(StringnewString, StringListaList) { … } • public String toString() { … } • public String getLineStartingWith(String prefix) { … } • } Methods

StringList: A Recursive Class public class StringList { // instance variables private booleanisEmpty; private String thisString; private StringListrestOfStringList; // constructors public StringList() { … } public StringList(StringnewString, StringListaList) { … } • public String toString() { … } • public String getLineStartingWith(String prefix) { … } }

StringList: In Action • StringListaList = new StringList(); public class StringList { // instance variables private booleanisEmpty; private String thisString; private StringListrestOfStringList; // constructors public StringList() { … } public StringList(StringnewString, StringListaList) { … } public String toString() { … } public String getLineStartingWith(String prefix) { … } } addr: 32 aList 32 true "" 0 toString() getLine()

StringList: In Action • StringListaList = new StringList(); public class StringList { // instance variables private booleanisEmpty; private String thisString; private StringListrestOfStringList; // constructors public StringList() { … } public StringList(StringnewString, StringListaList) { … } public String toString() { … } public String getLineStartingWith(String prefix) { … } } addr: 32 aList 32 true "" 0 toString() getLine() Actually a reference to a String object, but for brevity…

StringList: In Action • StringListaList = new StringList(); • aList = new StringList("mandolin", aList); addr: 32 aList 32 true "" 0 toString() getLine()

StringList: In Action • StringListaList = new StringList(); • aList = newStringList("mandolin", aList); addr: 32 addr: 48 aList 32 true false "" 0 toString() getLine() toString() getLine()

StringList: In Action • StringListaList = new StringList(); • aList = newStringList("mandolin", aList); addr: 32 addr: 48 aList 32 true false "" "mandolin" 0 toString() getLine() toString() getLine()

StringList: In Action • StringListaList = new StringList(); • aList = newStringList("mandolin", aList); addr: 32 addr: 48 aList 32 true false "" "mandolin" 0 32 toString() getLine() toString() getLine()

StringList: In Action • StringListaList = new StringList(); • aList= newStringList("mandolin", aList); addr: 32 addr: 48 aList 32 true false "" "mandolin" 0 32 toString() getLine() toString() getLine()

StringList: In Action • StringListaList = new StringList(); • aList= new StringList("mandolin", aList); addr: 32 addr: 48 aList 32 true false "" "mandolin" 0 32 toString() getLine() toString() getLine()

StringList: In Action • StringListaList = new StringList(); • aList= new StringList("mandolin", aList); addr: 32 addr: 48 aList 48 true false "" "mandolin" 0 32 toString() getLine() toString() getLine()

StringList: In Action • StringListaList = new StringList(); • aList = new StringList("mandolin", aList); addr: 32 addr: 48 aList 48 true false "" "mandolin" 0 32 toString() getLine() toString() getLine()

StringList: In Action • StringListaList = new StringList(); • aList = new StringList("mandolin", aList); • aList = new StringList("Lilly", aList); addr: 32 addr: 48 aList 48 true false "" "mandolin" 0 32 toString() getLine() toString() getLine()

StringList: In Action • StringListaList = new StringList(); • aList = new StringList("mandolin", aList); • aList = new StringList("Lilly", aList); addr: 77 addr: 32 addr: 48 false aList 48 true false "" "mandolin" "Lilly" 0 32 48 toString() getLine() toString() getLine() toString() getLine()

StringList: In Action • StringListaList = new StringList(); • aList = new StringList("mandolin", aList); • aList = new StringList("Lilly", aList); addr: 77 addr: 32 addr: 48 false aList 77 true false "" "mandolin" "Lilly" 0 32 48 toString() getLine() toString() getLine() toString() getLine()

HistoryList: A Recursive Class public class HistoryList { // instance variables private booleanisEmpty; private String firstWebSite; private HistoryListrestOfWebSites; // constructors public HistoryList() { … } public HistoryList(StringnewSite, HistoryListaList) { … } public booleancontains(String site) { … } public String toString() { … } public HistoryListgetMatches(String prefix) { … } public booleanisEmpty() { … } }

HistoryList: In Action • HistoryListaList = new HistoryList(); • aList = new HistoryList("cnn.com", aList); • aList = new HistoryList("mlb.com", aList); addr: 87 addr: 42 addr: 58 false aList 87 true false "" "cnn.com" "mlb.com" 0 42 58 contains() toString() getMatches() isEmpty() contains() toString() getMatches() isEmpty() contains() toString() getMatches() isEmpty()

HistoryList: contains() method public booleancontains(String site) { • if (empty) • { • return false; • } • else if (firstWebSite.equals(site)) • { • return true; • } • return restOfWebSites.contains(site); }

HistoryList: contains() • booleaninList = aList.contains("cnn.com"); addr: 87 addr: 42 addr: 58 false aList 87 true false "" "cnn.com" "mlb.com" 0 42 58 contains() toString() getMatches() isEmpty() contains() toString() getMatches() isEmpty() contains() toString() getMatches() isEmpty()

if (empty){ • return false; • } else if (firstWebSite.equals(site)) { • return true; • } • return restOfWebSites.contains(site); addr: 87 addr: 42 addr: 58 false aList 87 true false "" "cnn.com" "mlb.com" 0 42 58 contains() toString() getMatches() isEmpty() contains() toString() getMatches() isEmpty() contains() toString() getMatches() isEmpty()

if (empty){ • return false; • } else if (firstWebSite.equals(site)) { • return true; • } • return restOfWebSites.contains(site); true addr: 87 addr: 42 addr: 58 false aList 87 true false "" "cnn.com" "mlb.com" 0 42 58 contains() toString() getMatches() isEmpty() contains() toString() getMatches() isEmpty() contains() toString() getMatches() isEmpty()

if (empty){ • return false; • } else if (firstWebSite.equals(site)) { • return true; • } • return restOfWebSites.contains(site); true addr: 87 addr: 42 addr: 58 false aList 87 true false "" "cnn.com" "mlb.com" 0 42 58 contains() toString() getMatches() isEmpty() contains() toString() getMatches() isEmpty() contains() toString() getMatches() isEmpty() true

if (empty){ • return false; • } else if (firstWebSite.equals(site)) { • return true; • } • return restOfWebSites.contains(site); true addr: 87 addr: 42 addr: 58 false aList 87 true false "" "cnn.com" "mlb.com" true 0 42 58 contains() toString() getMatches() isEmpty() contains() toString() getMatches() isEmpty() contains() toString() getMatches() isEmpty() true

HistoryList: contains() • booleaninList = aList.contains("cnn.com"); true addr: 87 addr: 42 addr: 58 false aList 87 true false "" "cnn.com" "mlb.com" true 0 42 58 contains() toString() getMatches() isEmpty() contains() toString() getMatches() isEmpty() contains() toString() getMatches() isEmpty() true

HistoryList: contains() • booleaninList = aList.contains("cnn.com"); true true addr: 87 addr: 42 addr: 58 false aList 87 true false "" "cnn.com" "mlb.com" true 0 42 58 contains() toString() getMatches() isEmpty() contains() toString() getMatches() isEmpty() contains() toString() getMatches() isEmpty() true

Understanding Recursive Classes

Understanding Recursive Classes

Presentation Transcript

Recursive Learning

Recursive Functions

Recursive Backtracking

Understanding Classes

Recursive fury:

Recursive Definitions

Recursive Networks

Recursive Networks

Recursive methods

- recursive formula

Recursive

RECURSIVE FUNCTIONS

Recursive Sorting

Recursive Programming

Recursive program

Recursive Algorithms

Understanding Objects and Classes

Recursive relationship

Understanding Recursive Classes

Recursive Thinking

Recursive Definitions