Question

我不知道代码的错误，但我甚至不知道提交的基本知识。有人请帮忙。它输入标记和注册号甚至标记但不显示标记我该怎么办？

       class Info
            {
              public void writeFile() throws IOException{

     try{
         FileWriter f = new FileWriter("D:\\Student.txt");

      Scanner in=new Scanner(System.in);
      PrintWriter fw = new PrintWriter(f) ;
      System.out.println("Enter Student's Name");
      String name=in.nextLine();
      System.out.println("Enter Student's Reg.No");
      String reg_no=in.nextLine();
      Scanner inp=new Scanner(System.in);
      System.out.println("Enter Student's marks");
      int marks=inp.nextInt();
      fw.write(name);
      fw.write(reg_no);
      fw.write(marks) ;
      fw.close();
     }
      catch(Exception e)
       {
           System.out.println(e);
       }

  }

    public void readFile() throws IOException
    {
       try{ 
           FileReader reader =new FileReader("D:\\Student.txt");
        Scanner in=new Scanner(reader);
        while(in.hasNext())
         System.out.println(in.next());
         reader.close();

 }
       catch(Exception e)
       {
           System.out.println(e);
       }
}
}

Answer 1

此行fw.write(marks);之后int marks=inp.nextInt(); marks int write(int c) PrintWriter /** * Writes a single character. * @param c int specifying a character to be written. */ public void write(int c) { try { synchronized (lock) { ensureOpen(); out.write(c); } } ... ... } int / p>

character

负责将您的write(int c)编写为单StreamEncoder而不是int值，如果我们更深入的话，如果您看到源代码，则调用public void write(int c) throws IOException { char cbuf[] = new char[1]; cbuf[0] = (char) c; write(cbuf, 0, 1); }类中的int这种方法

char

它会将您的char值转换为char并存储到int，这意味着它会为您的int marks=inp.nextInt();存储等效的String marks=inp.nextLine();值如果您希望预期输出更改代码

@Component public class AccountHandlerMethodArgumentResolver implements HandlerMethodArgumentResolver { @Autowired private UserService userService; @Override public Object resolveArgument(MethodParameter methodParameter, ModelAndViewContainer mvContainer, NativeWebRequest request, WebDataBinderFactory webDataBinderFactory) throws Exception { Account account = null; Principal principal = request.getUserPrincipal(); if (principal != null) { String email = principal.getName(); User user = userService.findByEmail(email); if (user != null) { account = user.getAccount(); } } return account; } @Override public boolean supportsParameter(MethodParameter methodParameter) { return methodParameter.getParameterType().equals(Account.class); } } - ＆gt; Account

Answer 2

尝试在编写像

这样的代码时为String添加一些额外的空间

System.out.println("Enter Student's Name");
String name=in.nextLine()+" ";

最后，您的字符串Ali28809会像Ali 288 09那样存储在阅读您将获得的数据时 Ali 288 09

如果您希望输出与存储在文件中的输出相同，例如Ali 288 09 在readFile()使用nexLine()而不是next()

中更改您的代码

FileReader reader =new FileReader("D:\\Student.txt");
Scanner in=new Scanner(reader);
while(in.hasNext());
System.out.print(in.nextLine()); //here is the change
 reader.close();

并且您的输出为Ali 288 09希望这会对您有所帮助

为什么这段代码不起作用？ - 通过Scanner和PrintWriter进行归档

2 个答案: