在集合Java中存储和查询对象

Question

I'm working on a java project right now and am stuck. I'm trying to figure out how to first store a person object that has several elements like first name, last name, and ID. I know it's possible to create different collections for each part of the object but I'm wondering is it possible to create and query all elements in one collection? That is to say, after storing the objects in the collection, I want to interate through the collection to search for first name, last name, and ID.

This is my current code:

  public static void processRecords(String filenameIn)throws Exception{ 
    Scanner input = new Scanner(new File("students_mac.txt")); //retrieves data from file and stores
    input.nextLine();

    while (input.hasNextLine()) { //enters loop to process individual records and print them
            String line = input.nextLine(); 
            String[] tokens=line.split("\t"); // splits lines by tabs
            if(tokens.length!=4) 
                continue;
            Person student = new Person(FirstName, LastName, ID, Year);
            List<Person> list = new LinkedList<Person>();
            list.add(student);
        }

    List<Person> list=new LinkedList<Person>();
        for(Person student : list){
            System.out.println(student);
        } 

Answer 1

All you need is to move List<Person> list = new LinkedList<Person>(); out of while loop.

Scanner input = new Scanner(new File("students_mac.txt")); //retrieves data from file and stores
input.nextLine();

List<Person> list = new LinkedList<Person>();

while (input.hasNextLine()) { //enters loop to process individual records and print them
        String line = input.nextLine(); 
        String[] tokens=line.split("\t"); // splits lines by tabs
        if(tokens.length!=4) 
            continue;
        list.add(new Person(FirstName, LastName, ID, Year));
    }

    for(Person student : list){
        System.out.println(student);
    }