使用LinkedList输入和打印信息

Question

我有一个名为titanic.txt的文件，我需要读取此文件并创建一个LinkedList来存储所有信息。我似乎无法让它在main中正确打印。当我尝试运行程序时，我得到了一些奇怪的输出。

package project1;
import java.io.File;  
import java.util.Scanner;

import project1.LinkedList;

/**
while(line != null){
    //Create Object
    //  split line into 5 pieces first before creating object
    //Push that obj into the listObj
    //read another line
}
**/

public class Main {
    public static void main(String [] args){

        //Designate file to a variable
        String fileName = "titanic";
        //Create the linked list object(named pLinkedList)
        LinkedList pLinkedList = new LinkedList();
        //Run the try/catch in order to read the file and break up the 5 categories of data.
        try (Scanner scanner = new Scanner(new File(fileName))) {
            while (scanner.hasNext()){
                String [] passenger = scanner.nextLine().split(",");
                //System.out.println(passenger[0]); Prints out only the index of the passenger list, etc.
                //Create object using Passenger class and the 5 data categories we are analyzing.
                Passenger p = new Passenger(passenger[0],passenger[1],passenger[2],passenger[3],passenger[4]);

                pLinkedList.insertAtTail(p);

            }//While loop
        } catch (Exception e) {
            System.out.println("Failed to read");
        }


        pLinkedList.printList();
    }
}

package project1;

import project1.ListNode;

public class ListNode {

    //Variable data with type Object
    private Object data;
    //Variable nextNode with type ListNode
    private ListNode nextNode;

    //ListNode constructor
    public ListNode(Object newData){
        this.setNextNode(null);
        this.setData(newData);
    }

    //Constructor with two inputs
    public ListNode(Object newData, ListNode newNextNode){
        this.setNextNode(newNextNode);
        this.setData(newData);
    }

    public ListNode getNextNode() {
        return nextNode;
    }

    public void setNextNode(ListNode nextNode) {
        this.nextNode = nextNode;
    }

    public Object getData() {
        return data;
    }

    public void setData(Object data) {
        this.data = data;
    }
}

package project1;

import project1.EmptyListException;
import project1.ListNode;

public class LinkedList {

    private ListNode firstNode;
    private ListNode lastNode;
    private String listName;
    private int size;

    public LinkedList(){
        listName = "new list";
        size = 0;
        firstNode = lastNode = null;
    }

    public int size(){
        return size;
    }

    public boolean isEmpty(){
        if(firstNode == null){
            return true;
        }else{
            return false;
        }
    }

    public void insertAtHead(Object item){
        if(isEmpty()){
            ListNode newNode = new ListNode(item);
            firstNode = lastNode = newNode;
        }else{
            ListNode newNode = new ListNode(item, firstNode);
            firstNode = newNode;
        }
        size++;
    }

    public Object removeFromHead() throws EmptyListException{
        if(isEmpty()){
            throw new EmptyListException();
        }else{
            Object tempData = firstNode.getData();
            if(firstNode == lastNode)
                firstNode = lastNode = null;
            else
                firstNode = firstNode.getNextNode();
                size--;
                return tempData;
        }
    }

    public Object removeFromTail() throws EmptyListException{
        if(isEmpty()){
            throw new EmptyListException();
        }else{
            Object tempData;
            if(firstNode == lastNode){
                tempData = lastNode = null;
                return tempData;
            }else{
                ListNode current = firstNode;
                while(current.getNextNode() != lastNode)
                    current = current.getNextNode();
                tempData = lastNode.getData();
                lastNode = current;
                lastNode.setNextNode(null);
            }
            size--;
            return tempData;
        }
    }


    public void insertAtTail(Object item){
        ListNode newNode = new ListNode(item);
        if(isEmpty()){
            firstNode = lastNode = newNode;
        }else{
            lastNode.setNextNode(newNode);
            lastNode = newNode;
        }
        size++;
    }

    public void printList(){
        ListNode current = firstNode;
        while(current != null){
            System.out.println(current.getData().toString());
            current = current.getNextNode();
        }
    }


}

package project1;

public class Passenger {

    private String Index;       //Passenger number
    private String Standing;    //Passenger class(1st,2nd,...)
    private String Age;         //Passenger Age
    private String Sex;         //passenger gender (Male/Female)
    private String Survived;    //Passenger status(Alive/Deceased)

    public Passenger(String Index,String Standing,String Age,String Sex,String Survived){
        this.setIndex(Index);
        this.setStanding(Standing);
        this.setAge(Age);
        this.setSex(Sex);
        this.setSurvived(Survived);
    }

    public String getIndex() {
        return Index;
    }

    public void setIndex(String index) {
        Index = index;
    }

    public String getStanding() {
        return Standing;
    }

    public void setStanding(String standing) {
        Standing = standing;
    }

    public String getAge() {
        return Age;
    }

    public void setAge(String age) {
        Age = age;
    }

    public String getSex() {
        return Sex;
    }

    public void setSex(String sex) {
        Sex = sex;
    }

    public String getSurvived() {
        return Survived;
    }

    public void setSurvived(String survived) {
        Survived = survived;
    }

}