Homework 1 Solution

Create a class that can be used to test data structure - similar to the StudentA.java example found shown below:







StudentA.java




import java.util.Scanner;

import java.util.ArrayList;




class StudentA implements Comparable <StudentA {

static java.util.Random rn = new java.util.Random ();




static ArrayList <String firstNames = new ArrayList <();

static ArrayList <String lastNames = new ArrayList <();

static SORTBY
sortBy = SORTBY.LAST;
static int nextUID = 1;
String first,
last;
double gpa
=
0;
int credits
=
0;
int uid
=
0;



static {

try {




java.util.Scanner scFirst = new java.util.Scanner (new java.io.File("firstNames.txt"));




java.util.Scanner scLast = new java.util.Scanner (new java.io.File("lastNames.txt"));




while (scFirst.hasNext()) firstNames.add (scFirst.next()); while ( scLast.hasNext()) lastNames.add ( scLast.next());

}




catch (java.io.FileNotFoundException e) { System.out.println (e);

} // end try catch




} // end static intializer




enum SORTBY {LAST, FIRST, CREDITS, GPA}




public StudentA (String st) {this (new Scanner (st)) }




public StudentA (Scanner sc) {

uid
= nextUID++;
first
= sc.next();
last
= sc.next();
credits
=
sc.nextInt();
gpa
=
sc.nextDouble();
} // end Scanner constructor




public StudentA () {uid = nextUID++;} // no parameter constructor




public int compareTo (StudentA x) {

switch (sortBy) {




case LAST : return last.compareTo (x.last);

case FIRST : return first.compareTo (x.first);

case CREDITS: return credits - x.credits;




case GPA : return (gpa x.gpa)? 1 : -1;




} // end switch return 0;




} // end compareTo for Comparable interface




public String toString () {




return String.format ("%5d %15s, %15s: %5d %10.2f", uid, last, first, credits, gpa);

} // end method toString




public static StudentA [] makeRandom (int m) { StudentA [] sa = new StudentA [m];




for (int i = 0; i < sa.length; i++) {

sa[i]
= new StudentA ();
sa[i].first
= firstNames.get (rn.nextInt (firstNames.size()));
sa[i].last
=
lastNames.get (rn.nextInt ( lastNames.size()));
sa[i].credits = rn.nextInt (120);
sa[i].gpa
=
rn.nextDouble () * 4.0;



} // end for each student to instantiate return sa;




} // end method makeRanom




public static void main (String args []) {

System.out.println (new StudentA ("james robinson 35 3.98"));

StudentA [] x = makeRandom (10);




for (StudentA m: x)

System.out.println (m);

java.util.Arrays.sort (x);

System.out.println ("---- SORTED Last -----");

for (StudentA m: x)




System.out.println (m);

System.out.println ("---- SORTED First -----");

StudentA.sortBy = SORTBY.FIRST;

java.util.Arrays.sort (x);

for (StudentA m: x)




System.out.println (m);

System.out.println ("---- SORTED Credits -----");

StudentA.sortBy = SORTBY.CREDITS;

java.util.Arrays.sort (x);

for (StudentA m: x)




System.out.println (m);

System.out.println ("---- SORTED GPA -----");

StudentA.sortBy = SORTBY.GPA;

java.util.Arrays.sort (x);

for (StudentA m: x)




System.out.println (m);

} // end main

} // end class StudentA







Note that this class will be used in the projects in the rest of this course to test various data structures and algorithms

The following are requirements for this homework:




Unique index integer fields



Use at least 5 other fields of various, including at least one of each of String, int and double types.



o assume that the String's have no spaces within them




Write a method that will create an array of N random instances of this class, where N is an integer parameter to this method



Provide a toString method that will format an instance of this class nicely
Provide appropriate constructors
Write methods that will write and read text files of this class



to make this easy, assume that the first line of the file is the number of elements in the file
make the file one line per entry
use spaces as field delimiters in the files
use the toString method of the class to write to the file
Provide a good GUI interface to control and test this class, at a minimum:

use buttons to control the functions available
use JFileChoose for selecting input and output files
use a JTextArea and JScrollPane to create a scrolling text area for output



the window should resize nicely - use BorderLayout with the text area in the center



Submit your java file(s) along with your test plan and demonstration of successful compilation and running for all test cases to the homework 1 submission area.