ECE 462Object-Oriented Programmingusing C++ and JavaLecture 8Yung-Hsiang [email protected] 5 2Java List//ListOps.javaimport java.util.*;class ListOps {public static void main( String[] args ){List <String> animals = new ArrayList <String>(); animals.add( "cheetah" ); animals.add( "lion" ); animals.add( "cat" ); animals.add( "fox" ); animals.add( "cat" ); //duplicate cat System.out.println( animals ); //cheetah, lion, cat, fox, catdifferent from textbookfor Java 1.5week 5 3animals.remove( "lion" ); System.out.println( animals ); //cheetah, cat, fox, catanimals.add( 0, "lion" ); // overload, two arguments System.out.println( animals ); //lion, cheetah, cat, fox, catanimals.add( 3, "racoon" ); System.out.println( animals ); //lion, cheetah, cat, racoon, fox, catanimals.remove(3); System.out.println( animals ); //lion, cheetah, cat, fox, catListIterator iter = animals.listIterator();while ( iter.hasNext() ) { System.out.println( iter.next() ); }}}week 5 4Java Set (no duplicate element)//SetOps.javaimport java.util.*;class SetOps {public static void main( String[] args ){Set <String> animals = new TreeSet<String> (); //(A)animals.add( "cheetah" ); //(B)animals.add( "lion" ); //(C)animals.add( "cat" ); //(D)animals.add( "elephant" ); //(E)animals.add( "cat" ); // duplicate cat //(F)week 5 5System.out.println( animals ); //(G)// cat cheetah elephant lionSystem.out.println( animals.size() ); // 4 //(H)animals.remove( "lion" ); //(I}System.out.println( animals ); // cat cheetah elephant //(J)Iterator iter = animals.iterator(); //(K)while ( iter.hasNext() ) //(L)System.out.println( iter.next() ); //(M)// cat cheetah elephant}}week 5 6Java Map (Hash Table)//MapHist.javaimport java.io.*;import java.util.*;class WordHistogram {public static void main (String args[]) throws IOException{Map <String, Integer> histogram = new TreeMap<String, Integer>(); String allChars = getAllChars( args[0] ); StringTokenizer st = new StringTokenizer( allChars ); • array: integer → element• map: key (object, integer, string ...) → valueexample: name → phone number,student ID → departmentcity name → zip codeKeys are not necessarily continuous.week 5 7while ( st.hasMoreTokens() ) { String word = st.nextToken(); Integer count = (Integer) histogram.get( word ); histogram.put( word, ( count==null ? new Integer(1) : new Integer( count.intValue() + 1 ) ) ); }System.out.println( "Total number of DISTINCT words: " + histogram.size() ); System.out.println( histogram ); }week 5 8static String getAllChars( String filename ) throws IOException {String str = "";int ch;Reader input = new FileReader( filename );while ( ( ch = input.read() ) != -1 )str += (char) ch;input.close();return str;} }week 5 9Container Class (code reuse)• Many programs need "containers" to store information. Examples of containers include vector, list, stack, queue, map, and set.• A container needs to be able to hold items of different types (i.e. classes). Examples– list of strings, integers, floating points, student objects– queues of customer objects, car objects– maps: name → address, student ID → name, course title → classroom• C++ standard template library (STL) and Java container classes provide such functionality.week 5 10Select Container Class• All container classes have internal memory management, automatic allocation or release.• random or sequential accesses• allow unique or duplicate items• O(1) or O(N) for array-like access (using [index])• efficient insert / delete–front– end–middle• Java containers cannot store primitive types (int, char, float ...)week 5 11Efficiency O(1)O(N)O(N)insert/delete in middleO(1)O(1)+O(1)+insert/delete at endO(1)O(1)+O(N)insert/delete at frontO(N)O(1)O(1)array-like accesslistdequevectoroperationN: current number of itemsweek 5 12import java.io.*;import java.util.*;class Student {private int s_ID;private String s_name;private String s_department;public Student(int id, String nam, String dept) {s_ID = id; s_name = nam; s_department = dept;}public String toString() {String rtv = "\nID = " + s_ID + "\n\tname = " + s_name +"\n\tdepartment = " + s_department + "\n";return rtv;}}week 5 13class VectorClass {public static void main( String[] args ){Vector<Student> stdVec = new Vector<Student>();Student s1 = new Student(109032, "James", "Math");Student s2 = new Student(100075, "Amy", "ECE");stdVec.addElement(s1);stdVec.addElement(s2);System.out.println(stdVec);}}week 5 14class MapClass {public static void main( String[] args ){Map<Student, String> stdMap =new HashMap<Student, String>();Student s1 = new Student(109032, "James", "Math");Student s2 = new Student(100075, "Amy", "ECE");Student s3 = new Student(200069, "David", "CS");stdMap.put(s1, "Apartment 1, Lafayette");stdMap.put(s2, "Apartment 2, West Lafayette");System.out.println(stdMap.get(s1));System.out.println(stdMap.get(s3));}}week 5 15#include <iostream>#include <vector>#include <algorithm>#include <string>using namespace std;class Student{private:int s_ID;string s_name;string s_department;public:Student(int id, string nam, string dept):s_ID(id), s_name(nam), s_department(dept) { }friend ostream & operator << (ostream & os, const Student & std);};week 5 16ostream & operator << (ostream & os, const Student & std){os << endl << "ID = " << std.s_ID << endl<< "\tname = " << std.s_name << endl<< "\tdepartment = " << std.s_department << endl;return os;}int main(){vector<Student> vec;Student s1(7009, "Mary", "ECE");Student s2(7184, "Tom", "Physics");Student s3(6553, "Jennifer", "Chemistry");week 5 17vec.push_back( s1 );vec.push_back( s3 );vec.push_back( s2 );vector<Student>::iterator p = vec.begin();while (p != vec.end()){cout << (*p);p++;}}week 5 18Copy Constructorclass NameOfClass{NameOfClass(const NameOfClass & origobj) {// a constructor with special syntax// If a user does not provide a copy constructor// C++ compiler automatically creates one}}ECE 462Object-Oriented