java - 利用扫描仪填充对象数组列表

Question

我对编程相当陌生，最近我写了一些东西来利用扫描仪类从文本文件填充对象数组。本质上，我可以重写这个文本文件或添加新信息，而不必更改代码。我想我的问题是:有没有更简单/更优选的方法来做到这一点？我正在尝试学习编码的细微差别。

import java.io.*;
import java.util.*;
public class ImportTest {
public static void main(String[] args) throws IOException 
{
    Scanner s = null;
    Scanner k = null;
    ArrayList myList = new ArrayList<String>();
    ArrayList myList2 = new ArrayList<String>();
    ArrayList myList3 = new ArrayList<Student>();
    try 
    {
        s = new Scanner(new BufferedReader(new FileReader("testMe.txt")));
        while (s.hasNext()) 
        {
            myList.add(s.nextLine()); 
        }
    } 
    finally 
    {
        if (s != null) 
        {
            s.close();
        }
    }
    System.out.println("My List 1:");
    for(int i=0; i<myList.size(); i++)
    {
        System.out.println(i+". "+myList.get(i));
    }
    for(int x=0; x<myList.size(); x++)
    {
        try 
        {
            k = new Scanner(myList.get(x).toString());
            while (k.hasNext()) 
            {
                myList2.add(k.next()); 
            }
        } 
        finally 
        {
            if (k != null) 
            {
                k.close();
            }
        }
        String name;
        int age;
        double money;
        name=myList2.get(0).toString();
        age=Integer.parseInt(myList2.get(1).toString());
        money=Double.parseDouble(myList2.get(2).toString());
        Student myStudent=new Student(name, age, money);
        myList3.add(myStudent);
        myList2.clear();
    }
    System.out.println("Test of list object: ");
    for(int i=0; i<myList3.size(); i++)
    {
        System.out.println(i+". "+myList3.get(i).toString());
    }
}
}

Answer 1

我会逐行读取文件并直接解析每一行。这样您就不需要 3 个列表、2 个扫描仪和多次迭代:

String line = "";
BufferedReader br = new BufferedReader(new FileReader("test.txt"));
ArrayList<Student> students = new ArrayList<Student>();
while( (line = br.readLine()) != null)
{
   String[] tmp = line.split("\\s+");  //split line by spaces

   //this needs bounds & error checking etc.
   students.add(new Student(tmp[0], Integer.parseInt(tmp[1]), Double.parseDouble(tmp[2])));
}

在 Java 7 中，您可以使用 new file functions一次读取所有行:

List<String> allLines = Files.readAllLines("test.txt", Charset.defaultCharset());

不要忘记关闭阅读器或使用 try-with-resources (从java 1.7开始)