//--------------------- Registrar Class -----------------
import java.io.*;
import java.util.StringTokenizer;
/*********************************************************************
* This program, along with classes ArrayList, Student, and GradStudent,
* takes an input file, "Registrar6.dat", which contains the following
* on each line: "U" or "G" for undergraduate or graduate, the first name 
* followed by the last name, the social security number, the GPA, and 
* if the person is a grad student, the degree type (BS or AB).  
* The data is printed to an outfile, SOUT.
@author: Colin Joye, 1/01
@version: version 1
**********************************************************************/
public class Registrar {
  public static void main(String[] args) throws IOException {
    System.out.println("Colin Joye: Begin Program");
    String lastname, firstname, ssn, degree;
    double gpa=0.0;
    Double gpa_obj;
    String data="xxx", status, filename="Registrar6.dat";
    StringTokenizer reader;
    Student stud;
    GradStudent gstud;
    Object obj;
    ArrayList s1=new ArrayList(50);
    BufferedReader inFile=new BufferedReader(new FileReader(filename));
//loop to set up array of student data
    reader=new StringTokenizer(inFile.readLine());
    while(!reader.hasMoreTokens()) // skip blank lines.
      reader=new StringTokenizer(inFile.readLine());
    while(data != null && !s1.isFull() ){
      // get data from line.
      status   = reader.nextToken();
      firstname= reader.nextToken();        
      lastname = reader.nextToken();        
      ssn      = reader.nextToken(); 
      gpa_obj  = new Double(reader.nextToken());       
      gpa      = gpa_obj.doubleValue();
      degree   = status.equals("G")? reader.nextToken() : null;         
      // instantiate new Student or GradStudent.
      if(status.equals("U")){
        stud=new Student(firstname,lastname,ssn,gpa);
        s1.addItem(stud);
      }else{
        gstud=new GradStudent(firstname,lastname,ssn,gpa,degree);
        s1.addItem(gstud);
      }
      // try to get new line.
      try{
        reader=new StringTokenizer(inFile.readLine());
        while(!reader.hasMoreTokens()) // skip blank lines.
          reader=new StringTokenizer(inFile.readLine());
      }catch(NullPointerException ex){
        data=null;
      }
    }

    String file="SOUT";
    BufferedWriter bw= new BufferedWriter(new FileWriter(file));
    PrintWriter outFile=new PrintWriter(bw);
    outFile.println("Colin Joye");
    s1.print(outFile);

//remove student.      
    Student x=(Student)s1.getEntryAt(3);
    s1.delete(x);
    outFile.println("\n\nStudent deleted: objects[2]");  
    s1.print(outFile);
    outFile.println();

//put student back on.
    outFile.println("\nDeleted Student added back on");  
    s1.addItem(x);
    s1.print(outFile);
    outFile.println();

    outFile.println("\n\nColin Joye");
    outFile.close();

    System.out.println("outFile created: "+file);
    System.out.println("End program");
  } // close main. 
} // close class. 

//--------------------- ArrayList Class -----------------
/*****************************************************************
* This class, with classes Registrar, Student and GradStudent, keeps
* track of a list of Objects in an array.
@author: Colin Joye, 1/01
@version: version 1.0
*****************************************************************/
class ArrayList {
public static int START_POSITION=1;
public static int DEFAULT_SIZE=50;
private static int count=0; //count of items on list
private static Object[] objects;
//*****************************************************
// Instantiates NumEntries number of Objects in array.
public ArrayList(int NumEntries){
  objects = new Object[NumEntries];    
}// close constructor
//*****************************************************
// postcondition: Student is deleted from list and list is adjusted
public void delete(Object s){
  if( onList(s) ){
    for(int n=posList(s); n<(count-1); n++){
     objects[n]=objects[n+1];
    } // close for.   
  count--;
  } // close if
} // close method
/*****************************************************
* Precondition: List is not full.
* Postcondition: If the item was not 
* on the list, it has been added.                    */
public void addItem(Object item){
  if(!isFull())
    if(!onList(item))
      objects[count++]=item;  
} // close method
//*****************************************************
// determines if the list is full.
public boolean isFull() {
  return (count==objects.length);
} //end method.
//*****************************************************
// determines if the list is empty.
public boolean empty() {
  return (count==0);
} // close method.
/*****************************************************
* If the argument indicates a position on the list,
* then the entry at that specific position is returned;
* otherwise, null is returned.                       */
public Object getEntryAt(int position){
  if(position >= 0 && position < count)
    return objects[position-1];
  else return null;
} // close method.
/*****************************************************
* Returns true if position is the index of the
* last item on the list; otherwise, returns false.  */
public static boolean atLastEntry(int position){
  return (position==count);
} // close method.
//*****************************************************
// Returns the index of the student on the list.
public int posList(Object s){
  boolean found=false;
  int pos=0;
  while(pos < count && !found ){
    if(s.equals(objects[pos]))
      found=true;
    else pos++;
  }
 return pos;
} // close method.
/*****************************************************
* Returns true if the item is on the list
* otherwise, returns false.                          */
public boolean onList(Object s){
  boolean found=false;
  int i=0;
  while(i < count && !found ){
    if(s.equals(objects[i]))
      found=true;
    else i++;
  }
  return found;
} // close method.
//*****************************************************
// Returns the maximum allowable number of array elements.
public int maximumNumberOfEntries(){
  return objects.length;  
} // close method.
//*****************************************************
public void print(PrintWriter outFile){
  for(int index=0; index < count; index++){
    if(objects[index] instanceof Student ){
      outFile.print((Student)objects[index]);
    }else{
      outFile.print((GradStudent)objects[index]);
    }
  } 
} // close method.
//*****************************************************
}// close class.

//---------------------- Class Student --------------------------
/***************************************************************
* This class along with classes Registrar, ArrayList, and 
* GradStudent, creates a Student object.
@author: Colin Joye, 1/01
@version: version 1.0
***************************************************************/
class Student {
    protected String LastName, FirstName, SSN;
    protected double GPA;
    protected static int Count=0;
//**************************************************************       
public Student(String lastname,String firstname, String NewSSN, 
                                                  double NewGPA) {
    LastName = lastname;
    FirstName = firstname;
    SSN = NewSSN;
    GPA = NewGPA;
    Count++;
}  //  close constructor.
//**************************************************************       
public String toString() {  // method used to print out an object
     return ("\nThe Student's name is: "+LastName+" "+FirstName+
       ", SSN: " + SSN + ", GPA: " + GPA);
}  //  close method.
//**************************************************************       
public double getGPA(){
    return GPA;
}  //  close method.
//**************************************************************       
public String getSSN(){
  return SSN;
}  //  close method.
//**************************************************************       
public static int returnCount(){
    return Count;
}  //  close method.
//**************************************************************       
public void print(){
     System.out.println ("\nThe Student's name is: "+LastName+
       " "+FirstName+", SSN: " + SSN + ", GPA: " + GPA);
}  //  close method.
//**************************************************************       
//method to compare two objects.
public boolean equals(Object other){
      boolean result = false;
      if (LastName.equals(((Student)other).LastName))
         result = FirstName.equals(((Student)other).FirstName);
      return result;
} // close method.
//**************************************************************       
}  // close class.

//--------------------- GradStudent Class -----------------
/***********************************************************
* This class along with classes Registrar, ArrayList, and 
* Student, creates a GradStudent object.  The GradStudent 
* class is a child of the Student class.
@author: Colin Joye, 1/01
@version: version 1.0
***********************************************************/
class GradStudent extends Student {
  private String degree;  
  public GradStudent(String lname,String fname,String snum,double gpa,
                                                         String degtype){
    super(lname, fname, snum, gpa);
    degree=degtype;
  } // close constructor.
//*****************************************************
  public String toString(){
    return  super.toString()+ "\n  Degree: " + degree;
  } // close method.
//*****************************************************
  public void print(){
    String result = super.toString();
    result += "\n  Degree: " + degree;
  }
//*****************************************************
} // close class.