Tag Archives: OOP

Class Roster Array Version [Java] Assignment

Class Roster: This class will implement the functionality of all roster for school. It will , in essence, manage an Array of Student objects. Each roster will store a default of 10 Students

“global” Instance Variables
- private Student myStudents : an array storing Student Objects
- private String className (a name to represent a given roster like “Ap CS”)
- public int period //during which period of the day does this roster meet
a default constructor should initialize the Array to store 20 strings
a single parameter constructor that takes an Array <String>
Both constructors should initialize the instance variables
Methods
- Accessors
  - private int indexOf(Student st) //@returns index of Student St or -1
  - public boolean containsStudent(Student studentName )/ /@returns true if studentName is in roster .
  - public boolean equals(ClassRoster other) //@ returns whether or not rosters are equal. Rosters are equal if identical students are in identical order in the lists
- Mutators:

boolean addStudent( Student st ) ;//adds the student to the Roster

1	boolean addStudent( Student st ) ;//adds the student to the Roster

public void addStudent(String studentName, int age) ;// adds student name and age to end of roster

. Hint: Make user of the containsStudent() method
public boolean removeStudent(int ssnId ) // removes student from roster based on id. Make sure that you maintain the integrity of the parallel ArrayLists.

public boolean removeStudent(String name) //removes student based on name. Make sure that you maintain the integrity of the parallel ArrayLists.

public boolean removeStudent( Student st) //removes student st. Make sure that you maintain the integrity of the parallel ArrayLists.

Student Object (OOP Java)

Student Class

A school district decided to write a program to help keep track of various parts of the school.

It has been decided to store relevant information about Students in a Student class. Each Student will have an array of Strings to store the names of his or her teachers.

private instance variables

public class Student
{
public String name;
private int age
private double gpa;
private //insert array declaration;

public Student(){} // default constructor

boolean setTeacher (String name, int index){
//missing code
}

public void setGpa(double to){
//missing code
}

public double getGPA() // returns gpa


}

public class Student

{

public String name;

private int age

private double gpa;

private //insert array declaration;

public Student(){} // default constructor

boolean setTeacher (String name, int index){

//missing code

}

public void setGpa(double to){

//missing code

}

public double getGPA() // returns gpa

}

Part 1

* Construct the Java statement to declare the array called

teachersNames to store the String names of the student’s teachers

Part 2

write a default constructor
construct a method called addTeacher( String name) that adds String name to the teachersNames array
- to do this let’s create a private method private String[] addStr( String[] input, String val) that adds value to the end of the array and returns it. [redact]Solution[/redact]
construct hasTeacher(String name) that returns true if name is in the teachersName array
construct a method removeTeacher(String name) that removes the String name from the teachersNames array.
construct a method the line of code needed in the setGpa(double to) method of the Student Class.
construct a method boolean setTeacher (String name, int index) . This method should return true if index is valid in the array and false if index >= teachersName.length

Next: The runner class

Playlist Project [Array]

A PlayList project will be based on Three Classes

Artist
Song
PlayList

The Artist class will store core information about an artist

The Song class will store basic information about a music song

The PlayList class will manage lists of songs and artists

Artist

Constructor(s) :
public Artist( String name) { //missing code }

Instance Variables (“global” variables)

private String artistName ;
private Song[]  songs ; - an array storing the songs of this artist

1 2	private String artistName ; private Song[] songs ; - an array storing the songs of this artist

Methods

private int indexOf(String songName) // returns index position of parameter in the array 
public void addSong(Song song) 
public void removeSong(Song song) public void removeSongByName(String songName) 
public Song[] getSongs() //returns songs array
public String getName() // returns artistName

private int indexOf(String songName) // returns index position of parameter in the array

public void addSong(Song song)

public void removeSong(Song song) public void removeSongByName(String songName)

public Song[] getSongs() //returns songs array

public String getName() // returns artistName

Song

Constructor(s):

public Song(String songName, Artist artist){
//missing code 
}

public Song(String songName, Artist artist){

//missing code

}

Instance Variables

private Artist artist ;
public String songName ;
public long date //(date added to list)

private Artist artist ;

public String songName ;

public long date //(date added to list)

example of how to get current milliseconds as a long

Method

public Artist getArtist()

1	public Artist getArtist()

Artist

Song

PlayList

Instance Variables
- private String listName : This is the ‘name’ of your playList
- private Song[] songs;
- private int[] stars ; //how many stars each song has between 0 and 5 inclusive.
- Note: songs and stars are parallel Arrays
Constructor
- public PlayList(String name) : There should be only 1 constructor that takes a parameter representing the name of the playList
Accessor Methods
- public double averageRating() // returns the average star rating for the list
- public double averageRating(Artist artist) // returns the mean star rating associated with artist
- public Song[] getSongs(Artist artist) // returns an array populated by the songs of the parameter artist
- public Song[] getSongs() // returns all the songs in the list
Mutator Methods
- public void swap(Song song1 , Song song2 ) // switches positions of these two (maintain parallelism!)
- public void add(Song song , int stars)
- public void removeSong(Song song, String artist ) //removes song associated with artist
  - Note: Be careful here. You are allowed to add the same song and artist. Duplicates are allowed.
- public void removeArtist(Artist artist ) //removes all elements associated with artist
- public void removeLowStars(int cutOff) //removes all elements associated with a star rating less than cutOff
- ** public PlayList sortByDate() //this returns a rearranged PlayList based on each Song’s date
- ** public PlayList sortByRating() //this returns a rearranged playlist so that the 5 starred elements are the first group in the list, 4 stars second …1 stars, last
- ** public PlayList shuffle() //this returns a new PlayList in which all of the songs have been reordered randomly.

Artist

Song

PlayList

Account Abstract Class Assignment

This is the first part of a 2 part project.

Person Class

Constructor

public Person( String _name , int _age )

instance Variables

private String name
private int age

Methods

public String getName()
public int compareTo(Person other) { return this.age - other.age; }

Account – Abstract Super Class

Static Variable(s)

private static int nextAccountNum
private static int parentCompanyCode = 12810 ;

instance Variables

private int accountNumber// first account number should be 1
protected double balance
protected ArrayList<Person> owners

Constructor

public Account( double _balance, Person _owner) // add _owner to ArrayList owners

Methods

public static int getParentCode()
public int getAccountNumber()
public void deposit(double amount)
public double getCurrentBalance()
public abstract boolean withdraw(double amount)
public boolean equals(Account other) // are the unique account numbers equals ?
public String toString() Output should follow the conventions we have discussed. I will be testing for formatting like this :
public int comparesTo(Account other) { return this.accountNumber- other.accountNumber } (Note that this method has an ‘s‘ )
public void addOwner(Person p) //adds P to the ArrayList of owners
public ArrayList<Person> getOwners() // returns the ArrayList of owners
public Person remove( Person p) // this emulates the ArrayList’s remove() method (link) . Remember that that method removes the object and then returns the removed object. In this case, you should remove Person P from the ArrayList of owners

CheckingAccount extends Account
This class has to do certain things. You can decide the best way to do it. This class should have a way to
- attempt to withdraw money by writing a check. Every check should have a ‘check number’, which should be an integer. The lowest permissible value for a check number is 100 .
- public int writeCheck(double amount) // @ returns the check number of the written check
- public boolean cancelCheck(int checkNumber)
  - be able to cancel checks and keep track of the check numbers that have been cancelled
  - when a check is cancelled, the amount associated with that check is added back onto the balance.
  - return true if checkNumber is a valid check number; false otherwise.
One solution
- every time you write a check, you need a new check “#”
- writeCheck( double amount) - > tries to call this.withdraw(double amount) . You can then use ArrayLists to store check numbers, associated check amounts , things like that

SavingsAccount extends Account

instance variables

private double interestRate // //@ assumes that interest rate is not in decimal format i.e. 1.7 not .017

private ArrayList<Double> dailyBalances

static variables

public static final int MINIMUM_BALANCE=100; // this is the absolute minimum amount of money that must always be in the account

methods

public boolean withdraw(double amount) //@override the withdraw() method to ensure that currentBalance the never gets below MINIMUM_BALANCE

public void updateInterestRate(double newRate) //updates the interestRate

public void recordDailyBalance() // @ record current day’s balance by storing current balance in dailyBalances .

public ArrayList<Double> getDailyBalances() // @ return dailyBalances .

public double projectBalance(double timeInYears) // use the compound interest formula . Assume that the bank compounds the balance monthly. To learn more about how compound interest really works, click here .

You will need to convert interest rate from something like 1.7%, as an example , to 0.017

public void updateInterestPayment() // @ once a month update account based on average daily balances and interest rate.

*calculate the average monthly balance
* multiply balance by the interest rate (remember this must be converted to decimal)
* add that interest back onto the balance

public double getInterestRate()

public String toString() Output should follow the conventions we have discussed. I will be testing for formatting like this :

CertificateOfDeposit extends SavingsAccount

instance Variables

public static final double EARLY_WITHDRAW_PENALTY= 200 .

Methods

public boolean withdraw(double amount , boolean isEarly ) //@override the withdraw() and applies penalty to balance

Tester file :

import java.util.ArrayList;

public class Tester { 
    boolean verbose = false; //set to true for some expanded occasional error messages


    public Tester() {
        p2("Begin Testing");    
        p2("Version 4");    
        p2("set variable verbose to true if you want some occasional extra tips on errors");    
		p2("********************************************************************") ;
		p2("********************************************************************") ;
        doTest();
    }

    public void doTest(){

        int correct = 0;
        int wrong = 0;
        Person tyler = new Person("tyler", 18);
        Person joe = new Person("joe", 18);
        Person jim = new Person("jim", 17);

        if(tyler.compareTo(joe) == 0)
            correct++;
        else{
            p2("error @person, compareTo()");
            wrong++;
            }
        if(jim.compareTo(joe) == -1)
            correct++;
        else{
            p2("error @person, compareTo()");
            wrong++;
            }
        if(joe.compareTo(jim) == 1)
            correct++;
        else{
            p2("error @person, compareTo()");
            wrong++;
            }
        if( joe.getName().equals("joe"))
            correct++;
        else{
            p2("error @person, getName()");
            wrong++;

            }


        CertificateOfDeposit a = new CertificateOfDeposit(tyler, 120);
        double a_original_bal = a.getCurrentBalance();
        a.addOwner(joe);
        int a_num1 = a.getAccountNumber() ;    
		
		

        if (a_num1 != 1 ){
            wrong++    ;
            p2("First account 's id should be '1' ");
        }
        else 
            correct++;
    

        CertificateOfDeposit a2 = new CertificateOfDeposit(jim, 120);




    if(a2.getAccountNumber() <= a_num1){
            wrong++    ;
            p2("Unique account numbers not working correctly ");
        }
        else 
            correct++;


        if (a.getOwners().size() != 2)
            {
            p2("addOwner() not working ");
            wrong++    ;
            }
        else 
            correct++;

        a.remove(joe);
        if (a.getOwners().size() != 1)
        {
            wrong++ ;    
            p2("error , probably removeOwner() not working ");
        }
        else 
        {
            Person owner = a.getOwners().get(0);
            if(owner.getName().toLowerCase().equals("tyler"))    
                correct++;
            else
                {
                wrong++ ;    
                p2("error , probably removeOwner() not working ");
                }
        }


        if(Math.abs(a_original_bal - 120) > 0.000001)
		{
		p2 ("foo problem with setting  balance");
		wrong++;
		}
        else 
            correct++;


        
        a.deposit(25);
        if(Math.abs(a.getCurrentBalance() - 145) > 0.000001)
        {
            wrong++    ;
            p2("problem with setting  balance");
        }
        else 
            correct++;
        
        
        
        Person rob = new Person("rob", 18);
        CheckingAccount b = new CheckingAccount(rob, 200);
        b.deposit(500);
        b.withdraw(450);
        if( b.equals(a))
        {
        wrong++;    
            p2("Failed equals() test (Many things could cause this)");
        }
        else 
            correct++;

        if( a.equals(a) == false)
        {
        wrong++;    
            p2("Failed equals() test (Many things could cause this)");
        }
        else 
            correct++;


        double balanceNow = b.getCurrentBalance();
        int checkNum = b.writeCheck(4);
        // p2("checkNum : " + checkNum);
           if(checkNum >= 100) 
            correct++;
        else
        {
        wrong++;
        p2("error, Check Numbers cannot be lower than 100") ;
        }
       

        int check2Num = b.writeCheck(4);
        if(check2Num - checkNum == 1)
            correct++;
        else
        {
        wrong++;
        p2("error involving checknumbers. Should increment by 1") ;
        }

        if( balanceNow - b.getCurrentBalance() ==  8)
            correct++;
        else
            {
            wrong++;
            p2("Error involving writing checks and balance...could be various problems");
            if(verbose)
                p2("\t most likely your writeCheck() or withdraw() are the problem");
            }

        balanceNow = b.getCurrentBalance() ;
        int check3Num = b.writeCheck(242.1);

        if(check3Num - checkNum == 2)
            correct++;
        else
        {
        wrong++;
        p2("error involving checknumbers. Should increment by 1,even if the check bounces!") ;
        }

        if(balanceNow  == b.getCurrentBalance())
            correct++;
        else
        {
        wrong++;
        p2("Error involving bounced checks. You cannot withdrawal more than your current balance") ;
        p2("exiting testing program");
        return;
        }


        boolean badChkNum =  b.cancelCheck(50);
        if(badChkNum == false)
            correct++;    
        else
        {
        wrong++;
        p2("Error. cancelCheck on non existent check. Should return false, but didn't") ;
        p2("exiting testing program");
        return;
        }

        int check4Num = b.writeCheck(100);


        b.cancelCheck(check4Num);
        
        double balanceAferCancel = b.getCurrentBalance();
        if( balanceAferCancel == 242)
            correct++;
        else{
            wrong++;
            if(balanceAferCancel == 142)
                p2("cancelCheck() did not update balance. You still have deducted the amount for the check that is now cancelled");
            else
                p2("error , could be various things but most likely relateing to cancelCheck()/deposit()  ");
            }

        

        // if(balanceNow  == b.getCurrentBalance())
        //     correct++;
        // else
        // {
        // wrong++;
        // p2("Error involving bounced checks. You cannot withdrawal more than your current balance") ;
        // }


        Person roochi = new Person("roochi", 12);
        SavingsAccount c = new SavingsAccount(roochi, 110);
        boolean allGood = true;
        if(c.getCurrentBalance()== 110)
            correct++;
        else
        {
            allGood = false;
        wrong++;
        p2("error, could be constructor or getCurrentBalance()") ;

        }
        


        c.withdraw(5);
        if(c.getCurrentBalance()== 105)
            correct++;
        else
        {
            if(allGood )
                p2("error, probably withdraw()");
            else
                p2("error, could be constructor or getCurrentBalance() ") ;
        wrong++;
        }
        
        boolean isNull = false;
        try{
            
            c.addOwner(tyler);
        }
        catch( NullPointerException e){
        isNull = true;    
        
        }
    if(isNull)
        {
        p2("Looks like owners arraylist is null");
        p2("exiting program now, fix nullpointer first");
        wrong++;
        return;
        }
    else
        correct++;


//here 
// public String toString()





        Person james = new Person("Jim Adams II", 12);
        SavingsAccount jamesAcct  = new SavingsAccount(james , 666 );
        jamesAcct.addOwner(new Person("Jane Adams ", 34) );
        jamesAcct.addOwner(new Person("Jim Adams Sr", 35) );
        ArrayList<Person> owners = jamesAcct.getOwners();


        boolean anotherNull = false;
        try{
        jamesAcct.recordDailyBalance();
        }
        catch(NullPointerException e){
        anotherNull = true ;
        wrong++;
        }

    if(anotherNull)
        {
        wrong++;
        p2("NullPointer Exception Error, looks like you never initialized dailyBalances in SavingsAccount");
        p2("Exiting testing program");
        return;
        }
    else
        correct++;


    jamesAcct.updateInterestRate(3.3);

    if(jamesAcct.getInterestRate() == 3.3 )
        correct++;
    else{
        wrong++;
        p2("error, probably re: updateInterestRate()  or possibly getInterestRate()");
        }


    jamesAcct.recordDailyBalance();
    

    jamesAcct.deposit(22);
    jamesAcct.recordDailyBalance();
    jamesAcct.withdraw(100);
    jamesAcct.recordDailyBalance();
    jamesAcct.deposit(330);
    jamesAcct.recordDailyBalance();

     ArrayList<Double>  dailyBalances = jamesAcct.getDailyBalances(); 
    
    if(dailyBalances.get(0)== 666)
        correct++;
    else
        {
        wrong++;
        p2("error @ dailyBalances index 0");
        if(verbose)
            p2("\t\t 1st element of dailyBalances should be 666.00");
        
        p2("exiting testing program, fix daily balances first");
        return;
        }



    if(dailyBalances.get(1)== 666)
        correct++;
    else
        {
        wrong++;
        p2("error @ dailyBalances index 1");
        if(verbose)
            p2("\t\t 2nd element of dailyBalances should be 666.00");
        }
        
    if(dailyBalances.get(2)== 688)
        correct++;
    else
        {
        wrong++;
        p2("error @ dailyBalances index 2");
        if(verbose)
            p2("\t\t 3rd element of dailyBalances should be 666.00") ;
        }

    if(dailyBalances.get(3)== 588)
        correct++;
    else
        {
        wrong++;
        p2("error @ dailyBalances index 3");
        if(verbose)
            p2("\t\t 4th element of dailyBalances should be 588.00") ;
        }


    if(dailyBalances.get(4)== 918)
        correct++;
    else
        {
        wrong++;
        p2("error @ dailyBalances index 4");
        if(verbose)
            p2("\t\t 5th element of dailyBalances should be 918.00") ;
        }




    if( Account.getParentCode()== 12810)
        correct++;
    else{
        wrong++;
        p2("Account.getParentCode() wrong ");
        }

        //toString Tests
        String str = jamesAcct.toString();

    if(str.indexOf("SavingsAccount") == 0 )
        correct++;
    else{
        wrong++;
        p2("toString() should start w/classname. i.e. \"SavingsAccount\" ");
        }
    str = str.toLowerCase();

    if(str.contains("number") )
        correct++;
    else{
        wrong++;
        p2("toString() incorrectly formatted, Account number");
        }

    if(str.contains(jamesAcct.getAccountNumber() +"") )
        correct++;
    else{
        wrong++;
        p2("toString() incorrectly formatted, Account number");
        }

    if(str.contains("balance") )
        correct++;
    else{
        wrong++;
        p2("toString() incorrectly formatted, re: account balance");
        }

    if(str.contains(jamesAcct.getCurrentBalance() +"") )
        correct++;
    else{
        wrong++;
        p2("toString() incorrectly formatted, re: account balance");
        }

// ArrayList<Person> getOwners()    

    
    if(str.contains("owner") )
        correct++;
    else{
        wrong++;
        p2("toString() incorrectly formatted, re: Account Owners");
        }

    ArrayList<Person> jamesAcctOwners = jamesAcct.getOwners();
    for(Person p : jamesAcctOwners){
        String strName = p.getName().toLowerCase();
    if(str.contains(strName) )
        correct++;
    else{
        wrong++;
        p2("toString() incorrectly formatted, re: Account Owners");
        if(verbose)
                p2("\t\t " + str + "\n \t\t\t Missing " + strName);
        }
    }//end of for-each


    if(str.contains("interest rate") )
        correct++;
    else{
        wrong++;
        p2("toString() incorrectly formatted, re: interest rate ");
        }
    
    if(str.contains(jamesAcct.getInterestRate() + "") )
        correct++;
    else{
        wrong++;
        p2("toString() incorrectly formatted, re: interest rate ");
        }




    Person jorge = new Person("jorge", 17) ;
    CertificateOfDeposit cd_foo = new CertificateOfDeposit(jorge, 500);
    cd_foo.withdraw(100, true);
    double jorgesMoney = cd_foo.getCurrentBalance();
    if(jorgesMoney == 200 )
        correct++;
    else{
        wrong++;
        if( jorgesMoney == 400)
            p2("You did not apply the EARLY_WITHDRAW_PENALTY for a CD's early withdrawal");
        else
            p2("Certificate of Deposit has wrong balance after early withdrawal");

    }


Account sb = new SavingsAccount( jorge, 100 );
Account sb2 = new SavingsAccount( joe, 100);
if( sb2.comparesTo(sb) == 1)
	correct++ ;
else
	{
	wrong++;
	p2("Account's comparesTo not implemented correctly");
	}


SavingsAccount sb33 = new SavingsAccount( jorge, 100 );

sb33.updateInterestRate(3.3);
if( sb33.getInterestRate()== 3.3)
	correct++;
else
{
	wrong++;
	p2("Savings account error involving interestRate");
	p2("\t either getInterestRate() or , more likely, updateInterestRate() is wrong ");

}


double ball_yr1 = sb33.projectBalance(1);
if( Math.abs(ball_yr1 - 103.350372874721)< 0.000001)
	correct++ ;
else
	{
	wrong++;
	p2("SavingAccount's projectBalance() incorrect");
	}


	p2("********************************************************************") ;
	p2("********************************************************************") ;
	p2("                       SCORE  ") ;
	p2("********************************************************************") ;
	p2("********************************************************************") ;
	p2("********************************************************************") ;

    p2("-------------------------------");
    p2("Correct :  " + correct);    
    p2("Wrong   :  " + wrong);    
    
    }


void p2(String s){
    System.out.println(s);
}
void p2(int s){
    System.out.println(s);
}
void p2(boolean s){
    System.out.println(s);
}
    


}

Tester.java

When you are done, you can begin the Bank project .

Super Classes Are Great I

Question: What limitations seem to exist with our use of classes?

I. Implement all Methods of the Triangle and Rectangle methods below

Class: Rectangle Rectangle

Constructor

public Rectangle ( int _col, double _width, double _height)

instance Variables

private int color;
private double width;
private double height ;

Accessor Methods

public double getArea(); //returns the area of the rectangle
public int getColor()

Class: RightTriangle RightTriangle

Constructor

public RightTriangle( int _col, double _width, double _height)

instance Variables

private int color;
private double width;
private double height;

Accessor Methods

public double getArea(); //returns the area of the triangle
public int getColor()
public double getHypotenuse() ;

Class: InteractiveMath

download-bttn InteractiveMath-Arraylists (USE THIS ONE)

instance Variables

ArrayList<Rectangle> rectangles;
ArrayList<RightTriangle> triangles;

Accesor Methods

public double computeNetArea(){ //@ returns the area of the rectangles and triangles

Next : Super Classes are great 2

Then : constructors and inheritance.

after that : What is “Inherited” by Subclasses?

interactiveMath_arrays

Mr. M online

Mr. M's Stuff

Tag Archives: OOP

Class Roster Array Version [Java] Assignment

Student Object (OOP Java)

Student Class

Playlist Project [Array]

Artist

Song

PlayList

Account Abstract Class Assignment

Person Class

Account – Abstract Super Class

CertificateOfDeposit extends SavingsAccount

Super Classes Are Great I

Question: What limitations seem to exist with our use of classes?

Class: RightTriangle RightTriangle

Class: InteractiveMath