import java.util.ArrayList;
import java.util.Queue;
import java.util.LinkedList;
import java.util.List;
import java.util.ListIterator;
import java.util.Iterator;
import java.util.Scanner;
import java.io.*;
import java.util.StringTokenizer;


class LibItem{
private String id; // item id
private String title; // item title
public LibItem(String s, String t){
id = s;
title = t;
}
public String getID(){
return id;
}
public String getTitle(){
return title;
}
}
class PatronCopy{
// This class represents a record for every book copy borrowed by a patron

private int patron; // patron id
private int copy; // book's copy number
public PatronCopy(int x, int y){
patron = x;
copy = y;
}
public int getPatron(){
return patron;
}
public int getCopy(){
return copy;
}
}
class Book extends LibItem{
// This class represents a book and all its copies.

// book's authors
private List<String> authors = new ArrayList<String>();

// queue of copies on shelf
private Queue<Integer> onshelf = new LinkedList<Integer>();

// list of PatronCopy objects
private List<PatronCopy> onloan = new LinkedList<PatronCopy>();

// list of copies lost
private List<Integer> lost = new LinkedList<Integer>();

public Book(String s, String t){
super(s, t);
}
public void addAuthor(String s){
authors.add(s);
}
public int numAuthors(){
return authors.size();
}
public String getAuthor(int x){
if (x>0 && x<=authors.size()){
return authors.get(x-1);
}
return "";
}
public void addShelfCopy(int x){
if (x > 0)
onshelf.add(x);
}
public void addLost(int x){
if (x > 0)
lost.add(x);
}
public int checkOut(int patron){
if (onshelf.peek()!=null){
int c = onshelf.remove();
onloan.add(new PatronCopy(patron, c));
return c;
}
return -1;
}
public boolean checkIn(int c){
for (int i=0; i<onloan.size(); i++){
if (onloan.get(i).getCopy() == c){
onloan.remove(i);
onshelf.add(c);
return true;
}
}
return false;
}
public int numOnShelf(){
return onshelf.size();
}
public int numOnLoan(){
return onloan.size();
}
public int numLost(){
return lost.size();
}
public int getOnShelf(int x){
Iterator itr = onshelf.iterator();
for (int i=1; i<x; i++){
itr.next();
}
return (Integer)itr.next();
}
public String getOnLoan(int x){
ListIterator<PatronCopy> itr = onloan.listIterator();
for (int i=1; i<x; i++){
itr.next();
}
PatronCopy p = itr.next();
String s = Integer.toString(p.getCopy()) + " ";
s = s + Integer.toString(p.getPatron());
return s;
}
public int getLost(int x){
ListIterator<Integer> itr = lost.listIterator();
for (int i=1; i<x; i++){
itr.next();
}
return itr.next();
}
}

class Magazine extends LibItem{
// This class represents a copy of magazine.

// Volume number of the magazine
private int volume;

// Magazine status is 0 - on shelf -1 missing
private int status;

public Magazine(String d, String t, int v, int s){
super(d, t);
volume = v;
status = s;
}
public void setLost(){
status = -1;
}
public void setFound(){
status = 0;
}
public int getVolume(){
return volume;
}
public int getStatus(){
return status;
}
}

public class Homework4{

public static void loadItems(LinkedList<LibItem> libsys) throws IOException{
String id,title,authorLine,onshelf,lost,type,volume,status;
Scanner infile = new Scanner(new File("data.txt"));

while (infile.hasNext()){
type = infile.nextLine();
id= infile.nextLine();
title= infile.nextLine();
if(Integer.parseInt(type) ==1){
Book b1 = new Book(id, title);
authorLine = infile.nextLine();
onshelf = infile.nextLine();
lost = infile.nextLine();
StringTokenizer au = new StringTokenizer(authorLine);
while (au.hasMoreTokens()) {
b1.addAuthor(au.nextToken());
}
StringTokenizer onsh = new StringTokenizer(onshelf);
while (onsh.hasMoreTokens()) {
b1.addShelfCopy(Integer.parseInt(onsh.nextToken()));
}
StringTokenizer lt = new StringTokenizer(lost);
while (lt.hasMoreTokens()) {
if ((Integer.parseInt(lt.nextToken()))== -1){
return;
}
else{
b1.addLost(Integer.parseInt(lt.nextToken()));
}
}
libsys.add(new Book(id, title));


}
else if(Integer.parseInt(type) ==2){
volume=infile.nextLine();
status=infile.nextLine();
int newVolume =Integer.parseInt(volume);
int newStatus = Integer.parseInt(status);
libsys.add(new Magazine(id,title,newVolume,newStatus));

}
}
}
public static int menu(){
Scanner scan = new Scanner(System.in);
int choice;
System.out.println("Choose One");
System.out.println("1. Check Out a Book");
System.out.println("2. Check In a Book");
System.out.println("3. Search for Book by Title");
System.out.println("4. Search for Magazine by Title");
System.out.println("5. Patron Search");
System.out.println("6. Print Library Items");
choice = scan.nextInt();
while ((choice < 1) || (choice > 7)){
System.out.println("Invalid Selection - Try Again");
choice = scan.nextInt();
}
return choice;
}
public static void ProcessChoice(LinkedList<LibItem> libsys, int choice){
int itemid, amt;
Scanner scan = new Scanner(System.in);
switch (choice){
case 1: System.out.println("Check Out a Book");
System.out.println("Enter Book Id followed by Patron Id");
String BookId;
int patronId;
Book b;

/* b.getID();
b.checkOut(patronId);
/*
* prompt for book id and patron id
*/
break;
case 2: System.out.println("Check In a Book");
System.out.println("Enter Book Id followed by Patron Id");
/*
* prompt for book id and patron id
*/
break;
case 3: System.out.println("Search for a Book by Title");
System.out.println("Enter Book Id followed by Patron Id");

/*
* prompt for book title and search
*/
break;

case 4: System.out.println("Search for Magazine by Title");
System.out.println("Enter Magazine Title");
/*
* prompt for mag title and search
*/
break;
case 5: System.out.println("Patron Search");
System.out.println("Enter Patron Id");
b.getOnLoan(patronId);
break;

case 6: System.out.println("Print Library Items");
Magazine m1;

for(int i=0; i<libsys.size(); i++){
if(libsys.get(i) instanceof Book){
b=(Book)libsys.get(i);
System.out.println(b.getID()+" "+b.getTitle());

for(int a=0; a<b.numAuthors(); a++){
System.out.println(b.getAuthor(a));
}
for(int c=0; c<b.numOnLoan(); c++){
System.out.println(b.getOnLoan(c));
}
}
else {
m1 = (Magazine)libsys.get(i);
System.out.println(m1.getID()+" "+m1.getTitle()+
" "+m1.getVolume()+" "+m1.getStatus());
}
}


break;
}

}
public static void main(String args[]) throws IOException{
LinkedList<LibItem> libsys = new LinkedList <LibItem>();
loadItems(libsys);
int choice = menu();
ProcessChoice(libsys, choice);



}


}

I am having trouble with this program. I can't seem to load all the objects in? when i use case 6 of the process choice I only get the first object. Any and all advise would be helpful. thanks