Project #1 Solution

Create  a folder named  <asuriteid where asuriteid  is your  ASURITE user id (for example,  if your ASURITE user id is jsmith6 then your would be named  jsmith6)  and  copy all of your  .java source code files to this folder. Do not  copy the .class files or any   other   files.  Next,  compress   the  <asuriteid folder  creating   a  zip   archive  file  named   <asuriteid.zip     (e.g., jsmith6.zip). Upload  <asuriteid.zip  to the Blackboard Project  1 submission  link by the project  deadline.  Please  see the Course  Schedule  section in BB or in the Syllabus  for the deadline.  Consult the online  syllabus  for the late  and  academic integrity policies.

 

2   Learning Objectives

1.     Use the Integer wrapper  class.

2.     Declare and  use ArrayList class objects.

3.     Write code to read from, and  write to, text files.

4.     Write an exception handler  for an I/O exception.

5.     Write Java classes and  instantiate objects of those classes.

 

3   Background

Let  list be a nonempty  sequence  of nonnegative random  integers,  each  in the range  [0, 32767] and  let  n be the length  of

list, e.g.,

 

list = { 2, 8, 3, 2, 9, 8, 6, 3, 4, 6, 1, 9 }

 

where n = 12. List elements are numbered starting at  0. We define a run  up  to be a (k+1)-length subsequence  listi, listi+1, listi+2, ..., listi+k, that is monotonically increasing (i.e., listi+j   ≥ listi+j-1   for each j = 1, 2, 3, ..., k). Similarly,  a run  down is a (k+1)-length subsequence  listi, listi+1, listi+2, ..., listi+k, that is monotonically decreasing (i.e., listi+j-1  ≤ listi+j   for each

j = 1, 2, 3, ..., k). For the above example  list we have these runs  up and runs  down:

 

Runs Up

list0   through list1   = { 2, 8 }; k = 1

list2   = { 3 }; k = 0

list3   through list4   = { 2, 9 }; k = 1

list5   = { 8 }; k = 0

list6   = { 6 }; k = 0

list7   through list9   = { 3, 4, 6 }; k = 2

list10   through list11   = { 1, 9 }; k = 1


 

Runs Down

list0   = { 2 }; k = 0

list1   through list3   = { 8, 3, 2 }; k = 2 list4   through list7   = { 9, 8, 6, 3 }; k = 3 list8   = { 4 }; k = 0

list9   through list10   = { 6, 1 }; k = 1

list11   = { 9 }; k = 0

 

We are interested in the value of k for each run  up and  run  down and  in particular we are interested in the total umber  of

runs  for each nonzero  k, which we shall denote  by runsk,  0 < k < n - 1. For the example  list we have:

 

k           runsk      runs

1           4              { 2, 8 }, { 2, 9 }, { 1, 9 }, and { 6, 1 }

2           2              { 3, 4, 6, } and  { 8, 3, 2 }

3           1              { 9, 8, 6, 3 }

4-11     0             

Let runstotal  be the the sum from k = 1 to n - 1 of runsk.  For the example  list, runstotal = 4 + 2 + 1 = 7.

 

4   Software Requirements

Your program  shall:

 

1.       Open  a file named  p01-in.txt containing  n integers,  1 ≤ n ≤ 1000, with  each integer  in [0, 32767]. There  will be one or more integers per line. A sample  input file:

Sample p01-in.txt

2  8  3

2  9

8

6

3  4  6  1  9

2.     The program  shall compute runsk   for k = 1, 2, 3, ..., n - 1.

 

3.     The program  shall compute runstotal.

 

4.     The  program  shall produce  an  output file named  p01-runs.txt containing  runstotal  and  runsk    for k = 1, 2, 3, ...,  n - 1.

The file shall be formatted as shown in the example  file below.

 

Sample p01-runs.txt

runs_total,  7 runs_1,  4 runs_2,  2 runs_3,  1 runs_4,  0 runs_5,  0 runs_6,  0

5.       If the input file p01-in.txt cannot  be opened  for reading  (because  it does not  exist)  then display  an error  message on the output window and immediately terminate the program,  e.g.,

run program...

Sorry,  could not  open  'p01-in.txt'  for reading. Stopping.

 

5   Software  Design

Your program  shall:

 

1.       Contain  a  class  named  Main.  This  class  shall  contain  the main()  method.  The  main()  method  shall  instantiate an object of the Main class and  call run()  on that object.

// Main.java

public  class  Main  {

public  static  void  main(String[]  pArgs)  { Main  mainObject  = new  Main(); mainObject.run()

}

private  void  run()  {

// You  will  start  writing  code  here  to  implement  the  software  requirements.

}

}

2.       One of the primary  objectives  of this  programming project  is to learn  to use the java.util.ArrayList class. Therefore, you  are   not  permitted  to use  1D  arrays.   Besides,  you  will  quickly  discover  that  the ArrayList  class  is  more convenient to use than 1D arrays.

 

3.       ArrayList  is a generic  class meaning:  (1)  that it can  store  objects  of any  class; and  (2)  when  an  ArrayList  object  is declared  and  instantiated we  must  specify  the class  of the objects  that will  be  stored  in  the ArrayList.  For  this project, you need to define an ArrayList that stores integers, but you cannot  specify that your  ArrayList stores ints because  int is a primitive  data  type  and  not  a class.  Therefore,  you  will need  to use the java.lang.Integer wrapper class:

ArrayList<Integer  list  = new  ArrayList<():

int  x  = 1;

list.add(x);  // Legal  because of  Java autoboxing.

4.       You must  write an  exception handler that will catch  the FileNotFoundException that gets  thrown  when  the input file  does  not  exist  (make   sure  to  test  this).  The   exception  handler   will  print  the  friendly   error   message  and immediately terminate  the Java program. To  immediately terminate  a Java program  we call a static method  named exit()  which is in the java.lang.System class. The  exit()  method expects an int argument. For this project, it does not matter what  int argument we send to exit().  Therefore,  terminate the program  this way:

try  {

// Try  to  open  input  file  for  reading

}  catch  (FileNotFoundException  pExcept)  {

// Print  friendly  error  message

System.exit(-1);

}

5.       Your  programming skills should  be sufficiently  developed  that you are  beyond  writing  the entire  code for a program in  one  method. Divide  the program  into multiple methods. Remember, a  method should  have  one  purpose,  i.e.,  it should  do one thing.  If you find a method  is becoming  complicated because  you are  trying  to make  that method  do more than one thing, then divided  the method into 2, 3, 4, or more distinct methods, each of which does one thing.

6.       Avoid  making  every  variable  or object  an  instance  variable.  For  this  project  you  shall  not declare any  instance variables  in  the  class.  That  is,  all  variables   should   be  declared   as  local  variables   in  methods  and   passed   as arguments to other methods when appropriate.

7.       Format your  code neatly.  Use proper  indentation and  spacing.  Study the examples  in the book and  the examples  the instructor presents in the lectures and  posts on the course website.

8.     Put a comment header  block at the top of each method formatted thusly:

 

/**

*  A  brief  description  of  what  the  method  does.

*/

9.       Put a comment  header  block at  the top of each  source  code file—not  just for this  project,  but for every  project  we write—formatted thusly:

 

//********************************************************************************************************

// CLASS:  classname  (classname.java)

//

// DESCRIPTION

// A  description  of  the  contents  of  this  file.

//

// COURSE   AND  PROJECT  INFO

// CSE205  Object  Oriented  Programming  and  Data  Structures,  semester  and  year

// Project  Number:  project-number

//

// AUTHOR

// your-name  (your-email-addr)

//********************************************************************************************************

 

6   Pseudocode

Method  Run()  Returns  Nothing

Declare  and  create  an  ArrayList  of  Integers  named  list list  ←    ReadFile("p01-in.txt")

Declare and create an ArrayList of Integers named listRunsUpCount Declare and create an ArrayList of Integers named listRunsDnCount listRunsUpCount  ←   FindRuns(list,  RUNS_UP)

listRunsUpCount  ←   FindRuns(list,  RUNS_DN)

Declare  and  create  an  ArrayList  of  Integers  named  listRunsCount listRunsCount  ←    Merge(listRunsUpCount,  listRunsDnCount) Output("p01-runs.txt",  listRunsCount)

End  Method  Run

 

Method  FindRuns(In:  pList  is ArrayList  of  Integers;  int  pDir  is RUNS_UP  or  RUNS_DN)  Returns  ArrayList  of  Integers

listRunsCount  ←    arrayListCreate(pList.size(),  0) Declare  int  varaibles  i ←    0,  k  ←    0

While  i < pList.size()  - 1  Do

If pDir  is RUNS_UP  and  pList  element  at  i is ≤ pList  element  at  i + 1  Then

Increment  k

ElseIf  pDir  is RUNS_DN  and  pList  element  at  i is ≥ pList  element  at  i + 1  Then

Increment  k

Else


 

If k  =≠0 Then

Increment  the  element  at  index  k  of  listRunsCount k  ←    0

End  if

End  If

Increment  i

End  While

If k  =≠0 Then

Increment  the  element  at  index  k  of  listRunsCount

End  If

Return  listRunsCount

End  Method  FindRuns

 

Method  Merge(In:  pListRunsUpCount,  In:  pListRunsDnCount)  Returns  ArrayList  of  Integers

listRunsCount  ←    arrayListCreate(pListRunsUpCount.size(),  0)

For  i ←    0  to  pListRunsUpCount.size()  - 1  Do

Set  element  i of  listRunsCount  to  the  sum  of  the  elements  at  i in  pListRunsUpCount  and  pListRunsDnCount

End  For

Return  listRunsCount

End  Method  Merge

 

Method  arrayListCreate(In:  int  pSize;  In:  int  pInitValue)  Returns  ArrayList  of  Integers

Declare  and  create  an  ArrayList  of  Integers  named  list

Write  a  for  loop  that  iterates  pSize  times  and  each   time  call  add(pInitValue)  on  list

Return  list

End  Method  arrayListCreate

 

Method  Output(In:  pFilename;  pListRuns  ArrayList  of  Integers)  Returns  Nothing

out  ←    open  pFilename  for  writing out.print("runs_total,  ",  the  sum  of  pListRuns) For  k  ←    1  to  pListRuns.size()  - 1  Do

out.print("runs_k,  ",  the  element  at  index  k  of  pListRuns)

End  For

Close  out

End  Method  Output