Author Archives: Mr. M

Compiled and Interpreted Languages

Comilers and Interpreters

Retrieved from http://en.wikibooks.org/wiki/Introduction_to_Programming_Languages/Interpreted_Programs

Retrieved from http://en.wikibooks.org/wiki/Introduction_to_Programming_Languages/Interpreted_Programs

java-compiler-interpreter

retrieved from http://www.greenteapress.com/thinkapjava/html/thinkjava003.html

 

compiler_interpreter

retrieved from http://www.pasteur.fr/formation/infobio/python/ch05s02.html

 

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

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 Runner Part 2 

public class StudentsRunner2{

public static void main(String[] args){
//insert the line of code needed to create the Student object aStudent;
String teacher;
for (int i =0 ;i <  5; i++)
  {
   teacher= inputString("Enter a teacher");
   aStudent.addTeacher(teacher);
  }
}


}

1) Construct the Java statement to create the Student  object called aStudent  in the

StudentsRunner

 

2)

Back to the Student Class

 

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


}

 

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

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

 

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

 

 

Song

Constructor(s):

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

Instance Variables

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()

 

 

Artist

Song

PlayList

 

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