Question

我想验证客户端ID只有整数且不重复。 txt文件包含客户端详细信息，例如id，name等。 public void loadClientData（）{

    String fnm="", snm="", pcd="";
    int num=0, id=1;
    try {
        Scanner scnr = new Scanner(new File("clients.txt"));
        scnr.useDelimiter("\\s*#\\s*");
        //fields delimited by '#' with optional leading and trailing spaces  

        while (scnr.hasNextInt()) {
            id  = scnr.nextInt();
            snm = scnr.next();
            fnm = scnr.next();
            num = scnr.nextInt();
            pcd = scnr.next();

            //validate here type your own code

            if( id != scnr.nextInt()) {
                System.out.println("Invalid input! ");
                scnr.next();
            }   
        //some code...
        }
    }
}

它只会打印出第一个客户端。

任何帮助吗？

并且它已经过验证了吗？

这是client.txt

0001#  Jones#          Jack#           41#   NX4 4XZ#
0002#  McHugh#         Hugh#           62#   SS3 3DF#
0003#  Wilson#         Jonny#          10#   LO4 4UP#
0004#  Heath#          Edward#         9#    LO4 4UQ#
0005#  Castle#         Brian#          15#   LO4 4UP#
0006#  Barber#         Tony#           11#   LO4 4UQ#
0007#  Nurg#           Fred#           56#   NE8 1ST#
0008#  Nurg#           Frieda#         56#   NE8 1ST#
0009#  Mouse#          Mickey#         199#  DD33 5XY#
0010#  Quite-Contrary# Mary#           34#   AB5 9XX#

Answer 1

来自Scanner类的Java文档：

public int nextInt（）

将输入的下一个标记扫描为int。

对nextInt（）形式的此方法的调用完全相同   与调用nextInt（radix）的方式相同，其中radix是   此扫描仪的默认基数。

返回：       从输入扫描的int抛出：
InputMismatchException - if the next token does not match the Integer regular expression, or is out of range
NoSuchElementException - if input is exhausted
IllegalStateException - if this scanner is closed

如果扫描程序读取的是与InputMismatchException正则表达式不匹配的无效输入，则该函数将抛出Integer。

您可以使用try - catch块来验证该异常并处理＆＃34;错误＆＃34;你想要的方式

您的代码中还有其他问题。我修改了它并将解释放在评论中

public static void loadClientData() {



 try {
        String fnm = "", snm = "", pcd = "";
        int num = 0, id = 1;
        Scanner scnr = new Scanner(new File("clients.txt"));
        scnr.useDelimiter("\\s*#\\s*");
        //fields delimited by '#' with optional leading and trailing spaces
        //check for hasNext not hasNextInt since the next character might not be an integer
        while (scnr.hasNext()) {

            //here happens the integer validation

            try {
                id = scnr.nextInt();
            } catch (InputMismatchException ex) {
                System.out.println("Invalid input !");
            }
            System.out.print(id + "  ");
            snm = scnr.next();
            System.out.print(snm + "  ");
            fnm = scnr.next();
            System.out.print(fnm + "  ");
            num = scnr.nextInt();
            System.out.print(num + "  ");
            pcd = scnr.next();
            System.out.println(pcd + "  ");

            //you need to do this to get the scanner to jump to the next line
            if (scnr.hasNextLine()) {                    
                scnr.nextLine();
            }
            //validate here type your own code
            /* if (id != scnr.nextInt()) {
             System.out.println("Invalid input! ");
             //scnr.next();
             }*/

        }
    } catch (Exception ex) {

    }

}

如何验证java中的txt扫描程序数据

1 个答案: