使用扫描仪逐行读取文件并从数据中创建对象

Question

我的任务是使用扫描仪逐行读取文件并从每一行创建学生对象。

这是文本文件的布局：

id,first_name,last_name,username,password,UserType,permission,course,degree
35,Bartholom,Sapsedidiy,wbeeseb3,Q8yPvK4qm,Student,Reserve,EngineerI,Legal

我已确保进入新创建的学生对象的每个属性的顺序都是正确的。

我正在尝试获取每个逗号后的每个下一个字符串或整数，并将其分配给相关属性：

try
    {
        input = new Scanner(Paths.get("C:\Users\Home\Desktop\Student.txt"));
        input.useDelimiter(",");

        while(input.hasNext()) {
            int id = input.nextInt();
            String firstName = input.next();
            String lastName = input.next();
            String userName = input.next();
            String passWord = input.next();
            String type = input.next();
            enumUserType userType = enumUserType.valueOf(type.toUpperCase());
            String permission = input.next();
            enumPermissionType permissionType = enumPermissionType.valueOf(permission.toUpperCase());
            String course = input.next();
            String degree = input.next();

            Address userAddress = new Address(1, 23, "Fake street", "Suburb1", 2500, enumState.NSW);
            User user = new Student(id, firstName, lastName, userName, passWord, userType, permissionType, true, course, degree, userAddress);
            getLibrary().addUser(user);

        }
    }
    catch(IOException io)
    {
        System.out.println("Error opening file");
    }

事情马上就发生了，我在 int id 上收到了一个输入不匹配异常，这是第一个读取值，我不确定这里出了什么问题，我需要一些帮助来修复这个错误，

我只是刚开始学习 read/write 档案。也许我有一些错误的顺序或者它读取了错误的值？

提前致谢！

编辑：我的错误信息是：

Exception in thread "main" java.util.InputMismatchException
at java.util.Scanner.throwFor(Scanner.java:864)
at java.util.Scanner.next(Scanner.java:1485)
at java.util.Scanner.nextInt(Scanner.java:2117)
at java.util.Scanner.nextInt(Scanner.java:2076)
at library.Library.initData(Library.java:262)
at library.Library.main(Library.java:225)

第262行是：int id = input.nextInt();

Answer 1

试试这个 -

try
    {
        input = new Scanner(Paths.get("C:\Users\Home\Desktop\Student.txt"));
        while(input.hasNextLine()) {
            String[] line = input.nextLine().split(",");
            int id = Integer.parseInt(line[0]);
            String firstName = line[1];
            String lastName = line[2];
            String userName = line[3];
            String passWord = line[4];
            String type = line[5];
            enumUserType userType = enumUserType.valueOf(type.toUpperCase());
            String permission = line[6];
            enumPermissionType permissionType = enumPermissionType.valueOf(permission.toUpperCase());
            String course = line[7];
            String degree = line[8];

            Address userAddress = new Address(1, 23, "Fake street", "Suburb1", 2500, enumState.NSW);
            User user = new Student(id, firstName, lastName, userName, passWord, userType, permissionType, true, course, degree, userAddress);
            getLibrary().addUser(user);

        }
    }
    catch(IOException io)
    {
        System.out.println("Error opening file");
    }

或者，这也可以使用扫描仪来实现。

try
    {
        input = new Scanner(Paths.get("C:\Users\Home\Desktop\Student.txt"));
        while(input.hasNextLine()) {
            Scanner line = new Scanner(input.nextLine());
            line.useDelimiter(",");
            int id = line.nextInt();
            String firstName = line.next();
            String lastName = line.next();
            String userName = line.next();
            String passWord = line.next();
            String type = line.next();
            enumUserType userType = enumUserType.valueOf(type.toUpperCase());
            String permission = line.next();
            enumPermissionType permissionType = enumPermissionType.valueOf(permission.toUpperCase());
            String course = line.next();
            String degree = line.next();

            Address userAddress = new Address(1, 23, "Fake street", "Suburb1", 2500, enumState.NSW);
            User user = new Student(id, firstName, lastName, userName, passWord, userType, permissionType, true, course, degree, userAddress);
            getLibrary().addUser(user);

        }
    }
    catch(IOException io)
    {
        System.out.println("Error opening file");
    }

但我更喜欢前一种方式。

使用扫描仪逐行读取文件并从数据中创建对象

Reading from a file using scanner, line by line and creating an object out of the data

java

file-io