使用scanner从Java文本文件中获取和存储变量

Question

id=1 name=biology instructor=John Smith room=2

Java文件

public class Subject {
   Integer id;
   String name;
   String instructor;
   Integer room;

   public void importSubject() throws IOException{
   //gets data from file and places it into variable
      File list = new File("subjects.txt");
      Scanner reader = new Scanner(list);
      while (reader.hasNextLine()) {
        String [] data = reader.newLine.split("=");
        this.id = Integer.parseInt(data[0]);
        this.name = data[1];
        this.instructor = data[2];
        this.room = Integer.parseInt(data[3]);
      }
   } 
}

Answer 1

假设文件的内容总是按照“id”、“name”、“instructor”、“room”的顺序排列，那么实现这一点的一种方法就是为扫描器使用自定义分隔符：

Scanner reader = new Scanner(list);
reader.useDelimiter("\\s*(id|name|instructor|room)=");

id=、name=、instructor=和room=（包括前导空格）都与分隔符模式\s*(idnameinstructorroom)=匹配，因此扫描程序将只给我们这些分隔符之间的标记，它们是：

• 1
• 生物学
• 约翰·史密斯
• 2

if (reader.hasNextLine()) {
    this.id = reader.nextInt();
    this.name = reader.next();
    this.instructor = reader.next();
    this.room = reader.nextInt();
}

public static List<Subject> readSubjects() throws IOException {
    File list = new File("subjects.txt");
    Scanner reader = new Scanner(list);
    ArrayList<Subject> list = new ArrayList<>();
    while (reader.hasNextLine()) {
        Subject newSubject = new Subject();
        newSubject.id = reader.nextInt();
        newSubject.name = reader.next();
        newSubject.instructor = reader.next();
        newSubject.room = reader.nextInt();
        list.add(newSubject);
    }
    return list;
}