this is one assignment

There will be a discussion in class about this assignment

What to do.

Create a simple database with three fields : ID, LastName,FirstName all as Strings. You should define a class calledStudentRecord or DataBaseRecordwith three private String elements (the three fields), along withthe appropriate methods. Here's what mine looked like:

public class StudentRecord{

    private String fname;

    private String lname;

       private String ID;

    DataBaseRecord(String f,String l,Stringi)

    {

      this.fname=f;

        this.lname=l;

      this.ID=i;

    }

  

   

public String toString()

    {

        return(fname+\"\"+lname+\" \"+ID);

    }

  

    public int compareTo(StudentotherStudent)

    {

       return(LastName.compareTo(otherStudent.LastName));

    }

      

}

You should also declare an object called DataBaseArray which isan array of DatabaseRecords. Records of type DataBaseRecord shouldbe added at the end of the DataBaseArray. Create an IndexRecordclass:

public class IndexRecord {
private String key;
private int where;

//other stuff here
}

Now create an IndexArray. This is an array of IndexRecord and isto be implemented That is, insertions must maintain the order inthe array, where order is maintained by the key value. Note thatthis means you need to define a compareTo method in the IndexRecordobject.

The OrderedArray class was an array of objects of type Student.To print out the array, we included a method called printIt() thatprinted out the entire array. But suppose we wanted to do thefollowing: we wish to retrieve an element from the array, dosomething with it, and then retrieve the next element in the array.Why (or when) you might wish to do this will become apparent as youwork on the programming assignment.

We need an iterator.

An iterator is an element that is part of the OrderedArray object;it is a current pointer to an element in the array. We caninitialize this pointer to the beginning of the array or the end.We can advance the pointer forward or backward.
Finally, and most importantly, we can retrieve the element in arrayreferenced by the iterator. The declaration of an iterator in ourexample would be:

public class OrderedArray
{
    private Student data[ ];
    private int nextElem;
    private int maxSize;
    private int theIterator;            //we add an iterator;

    .......
   
We can initialize the iterator to reference the beginning of thearray or the end of the array. We agree that if the array is empty,either initialization should set the iterator to -1:

public void setIteratorBegin()
{
    theIterator=(nextElem>0? 0 : -1);
}
public void setIteratorEnd()
{
    theIterator=(nextElem>0 ? nextElem-1 :-1);
}

Finally, there are three methods that return an instance of aStudent:

/* getIterator returns a reference to the Student currentlyreferenced by theIterator
/*      if theIterator==1 return -1

public Student getIterator()
{
    return(theIterator==-1 ? null:data[theIterator]);
}

/* advance theIterator. If we run off end, set to -1
/* if theIterator==-1 return null, else the reference to the entryin the array

public Student getIteratorNext()
{
   theIterator=(theIterator==nextElem-1? -1:theIterator+1);
   return(theIterator==-1? null :data[theIterator]);
}

/* decrement theIterator. If we run offthe beginning of the array, set to -1
/* if theIterator==-1 return null, else the reference to the entryin the array

public Student getIteratorPrev()
{
    theIterator=(theIterator==0? -1:theIterator-1);
    return(theIterator==-1?null:data[theIterator]);
}

So what does all this get us ? See the following code to traversethe array foward or in reverse:


public class UseOrderedArray {

    public static void main(String[] args)
    {
       
        Student s;
        OrderedArray myArray=newOrderedArray(20);
              
        myArray.insert(newStudent(\"smith\",16,(float)2.7));
        myArray.insert(newStudent(\"adams\",15,(float)3.1));
        myArray.insert(newStudent(\"morris\",17,(float)3.3));
       
        // print in reverseorder
       
       myArray.setIteratorEnd();
        for(s=myArray.getIterator();s!=null;s=myArray.getIteratorPrev())
           System.out.println(s);
       
        // print in forwardorder
       
       myArray.setIteratorBegin();
        for(s=myArray.getIterator();s!=null;s=myArray.getIteratorNext())
           System.out.println(s);
           
    }

}

The data! Please note the format is:    last_name first_name student_IDRead into your own file        Dunn Sean        31111    Duong Geoffrey     29922    Fazekas Nicholas    31100    Prezioso Stefano     22223    Puvvada Mohana    11224    Ravikumar Rakhi      11226    Salyers Matthew   11227       Gillespie William    49587    Hess Caleb      29282     Armatis Jared  34512      Beckman Allan  35176    Wang Zhen        22113    Wingett Jordan     12345    Belt Keith   34987    Bixler Tyler  22234    Chambers Quentin    22567    Chinni Adithya   28456    Donheiser Michael    28456    Kondrashov Mikhail  33331    Kraus Laura     33332    Krupp Phillip    49888    Maass John      44112    McCarty Amanda    44223    Moldovan Gregory   44335    Oshiyoye Adekunle  44556        Pagalos Frank    33112    Perski Zackery    33221     Saunders Jordan    77556       Simpson Ashlynne   77665       Szalai Kyle     33112     Witting Robert     21354  

/**
* This will be the main driver program for many of your programs.Specifically,
* you will need to define a data structure and related algorithmsto use with this program.
* We will be using the data file I have provied for you: a file of68 records. Each record is composed
* of three fields:
*      String lastName
*      String firstName
*      String ID
* ID may be implemented as an integer, but it is easier toimplement as a string. Both lastName and firstName
* may not be unique, but the ID **is** unique.
*
*
*/






import java.util.*;

public class COSC311Driver
{

       
   
    public static void main(String[] args)
    {
        /*The followingdeclaration declares a data structure that will change from oneassignment to the next. For example, you will need toimplement
         * the following asa doubly linked list, as well as a tree.
         */
       
    
        DataBase d=newDataBase();
        int response;
        Scanner keyboard=newScanner(System.in);
       
       
        /* Read the data intothe database from the external disk file here
         * IMPORTANT:duplicate ID numbers should not be added. Disregard
         * the entirerecord for duplicate IDs
         */
       
       
       
       
        do
        {
           System.out.println(\" 1 Add a new student\");
           System.out.println(\" 2 Delete a student\");
           System.out.println(\" 3 Find a student by ID\");
           System.out.println(\" 4 List students by ID increasing\");
           System.out.println(\" 5 List students by first nameincreasing\");
           System.out.println(\" 6 List students by last nameincreasing\");
           System.out.println(\" 7 List students by ID decreasing\");
           System.out.println(\" 8 List students by first namedecreasing\");
           System.out.println(\" 9 List students by last namedecreasing\");
           System.out.println(\" \");
           System.out.println(\" 0 End\");
           
           response=keyboard.nextInt();
           
           switch (response)
           {
               case 1: d.addIt();    //Note: if the user enters an IDalready in use, issue a warning and return to the menu
                       break;
               case 2: d.deleteIt(); //Note: output either \"Deleted\" or \"ID notFound\" and return to menu
                       break;
               case 3: d.findIt();   //Note: output the entire record orthe message \"ID not Found\" and return to menu
                       break;
               case 4:d.ListByIDAscending();              
                       break;
               case 5: d.ListByFirstAscending();    
                       break;
               case 6: d.ListByLastAscending();
                       break;
               case 7: d.ListByIDDescending();
                       break;
               case 8: d.ListByFirstDescending();
                       break;
               case 9: d.ListByLastDescending();
                       break;
               default:               
           }
           
        } while(response!=0);
    }
}