Author Archives: Mr. M

Problem Solving Process

The problem Solving Process (ch 7.1)

Taken From JB Learning’s super awesome book/powerpoint set “Computer Science Illuminated

http://www.jblearning.com/catalog/9781449672843/

Compiled and Interpreted Languages

Comilers and Interpreters

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

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

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

Alice- What as a String

You cannot place a number variable into the say() method

You must use the World function : what as a string

NEXT: asking user for input and saying it

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 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);
  }
}


}

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

Back to the Student Class

Students Runner Class

public class StudentsRunner{

public static void main(String[] args){

Student dom;

}


}

public class StudentsRunner{

public static void main(String[] args){

Student dom;

}

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

StudentsRunner

Next to Student Runner Part 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


}

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

Leadership Qualities

Read the following articles and answer handout questions

Steve Jobs article : http://www.forbes.com/sites/jackzenger/2013/08/22/the-big-lesson-about-leadership-from-steve-jobs/

Mark Zuckerberg #1 http://www.inc.com/ekaterina-walter/as-zuckerberg-turns-30-leadership-lessons.html

Mark Zuckerberg #2 [article taken down 🙂 ]

Array Fun 2

Java Assignment

Create a Class called ArrayFun2 that has the following methods Write the body for the methods described below.

int[] digitsToArray(int num)

1	int[] digitsToArray(int num)

Description: This method creates an array that is filled with all of the digits of nums.

Method Call	return value/output
digitsToArray( 523 )	{3, 2, 5}
digitsToArray(1267 )	{ 7 , 6 , 2, 1 }

public boolean allFactorsOfSum(int[] nums)

Description: This method returns true if each element ofnums is a factor of the sum of nums.

Method Call	return value/output
allFactorsOfSum( {6,1,2,3} )	true (because all of the elements are factors of the sum which is12)
allFactorsOfSum( 1,4,7)	false (because 7 is not a factor of the sum of this array which is 12)

public String[] doubleArr(String[] strs)

Description: This method returns a new version of strs with each element appearing twice.

Method Call	return value/output
doubleArr( {“a”,”b”,”c”} )	{“a”,”a”,”b”,”b”, “c” , “c”}
doubleArr( {“math”,”ware”,”house”,”.com” })	{“math”,”math”,”ware”,”ware”,”house”,”house”,”.com”, “.com”}

public boolean isThere(int[] nums, int num)

Description: This method returns true if num is an element nums.

Method Call	return value/output
isThere( {6,1,2,3}, 6)	true
isThere( {6,1,2,3}, 5 )	false

public int indexOf(int[] nums, int num)

Description: This method returns the index value of the first appearance of num or -1 if num is not an element of nums .

Method Call	return value/output
indexOf( {6,4 ,7,3, 4 }, 4)	1
indexOf( {6,4 7 ,3,2,7}, 7)	2
indexOf( {6,4 ,2,3}, 22)	-1

public int lastIndexOf(int[] nums, int num)

Description: This method returns the index value of the last appearance of num or -1 if num is not an element of nums .

Method Call	return value/output
lastIndexOf( {6, 4 ,7 ,3, 11, ,4}, 4)	5
lastIndexOf( {7, 6,4 , 7 ,3}, 7)	3
lastIndexOf( {6,4 ,2,3}, 22)	-1

public boolean isIncreasing(double[] nums)

Description: This method returns true if each element in nums is greater than the element to its left.

Method Call	return value/output
isIncreasing( {1,2,3,4 })	true
isIncreasing( {1,0 ,3,4 })	false
isIncreasing( {1,1, 2,3,4 })	false

public int largestSpan(int[] nums)

Description: This method returns the largest span of consecutive increasing numbers

Method Call	return value/output
largestSpan( {4, 3, 1, 2, 3 , 1} )	3
largestSpan( {4 , 3, 1 , 12 , 31 , 44 , 52 , 1} )	5
largestSpan( {9, 7, 8 , 12,4, 3, 0, 4 , 1)	3
largestSpan( {1, 0, 4, 5 , 3, 2, 8 , 9, 10, 12, 4, 3, 1 })	5

** int[] invert(int[] nums)

Description: This method ‘inverts’ an array by spliting the array in halves and ‘inverting’ each half. See sample calls to understand.

Method Call	return value/output
invert( {5 , 21, 5, 13,4 })	{4, 13, 5, 21, 5 }
invert( { 1, 2, 3, 4, 5,6 })	{ 6, 5, 4, 3, 2, 1}

** int[] shiftByN(int[] nums, int delta)

Description: This method returns the array with all digits shifted by delta . Any digits that are circulated off the end of the array should be returned to the other side. Note: delta could be positive or negative. Please keep in mind that Math.abs(delta) > nums.length could be possible 😉

Method Call	return value/output
shiftByN( {5 , 21, 13,4 } 1)	{ 4 , 5 , 21, 13 }
shiftByN( {5 , 21, 13, 4 , 11} 2)	{ 4 , 11 , 5 , 21, 13}
shiftByN( {5 , 21, 13, 4 } -1)	{ 21, 13, 4 , 5}
shiftByN( {5 , 21, 13, 4 ,7 } -2)	{ 13, 4 ,7 , 5 , 21}

** int[] add(int[] num1, int[] num2, int base) throws ArithmeticException@precondition 1 < base < 11
@precondition num1.length = 5 and num2.length = 5
@postcondition: the returned array has 5 elements representing the sum or an ArithmeticException is thrown

Description: This method attempts to replicate addition. Consider both num1 and num2 represent the five digits of a number. Each element in the array stores one of the digits. For instance, the number 143 would be represented as {0,0,1,4,3 }. Numbers can be in any base between 2 and 10 inclusive , and the number 10110₂ in binary would appear in an arrays as : {1, 0, 1 , 1, 0 } . Let’s assume the numbers are positive.You should return an array representing the digits of the sum of num1 and num2. If the number of digits in the sum exceeds the maximum number of digits (5) , you should throw an arithmetic exception as shown in the code below:

if(overFlowAdditionOccurred) throw new ArithmeticException("Addition Overflow Error");

1
2

if(overFlowAdditionOccurred)
throw new ArithmeticException("Addition Overflow Error");

Note: You may not use any kind of helper or utility methods that are built into pre-defined Java classes for converting numbers between bases. Only use techniques taught in this class.

Method Call	return value/output
add( {0,0,0 ,4,2},{0,0,0,5,1}, 10)	{0, 0, 0, 9, 3} ie (42 + 51 = 93)
add( {0, 0, 0 ,7,2},{0,0,0,5,1}, 10)	{0, 0 , 1 , 2, 3} ie (72 + 51 = 123)
add( {0, 0 , 0 , 1 , 1}, { 0 , 0 , 0 , 1 }, 2)	{0, 0 , 1 , 0 , 0} ie ( 11₂ + 1₂= 100₂ )

Mr. M online

Mr. M's Stuff

Author Archives: Mr. M

Problem Solving Process

The problem Solving Process (ch 7.1)

Compiled and Interpreted Languages

Alice- What as a String

Class Roster Array Version [Java] Assignment

Student Runner Part 2

Students Runner Class

Student Object (OOP Java)

Student Class

Playlist Project [Array]

Artist

Song

PlayList

Leadership Qualities

Array Fun 2

Java Assignment