Question

我想验证名称是否包含特殊字符。请告诉我这段代码有什么问题？我的代码是：

import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Name {
    static Scanner in = new Scanner(System.in);

    public static String verifyName() {
        System.out.print("Enter your name: ");
        String name = in.nextLine();
        Pattern p = Pattern.compile("[a-zA-Z0-9]*");
        Matcher m = p.matcher(name);
        if(!m.matches()) {
            System.out.println("Invalid Name");
            verifyName();
        }
        return name;
    }

    public static void main(String args[]) {
        String result = verifyName();
        System.out.print(result);
    }
}

输出：

Enter your name: @li
Invalid Name
Enter your name: #sd
Invalid Name
Enter your name: Zain
@li

必填项：

Enter your name: @li
Invalid Name
Enter your name: #sd
Invalid Name
Enter your name: Zain
Zain

提前致谢！

Answer 1

您的整个代码应该像

extension String {
    func fromUTCToLocalDateTime() -> String {
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss"
        dateFormatter.timeZone = TimeZone(abbreviation: "UTC")
        var formattedString = self.replacingOccurrences(of: "Z", with: "")
        if let lowerBound = formattedString.range(of: ".")?.lowerBound {
            formattedString = "\(formattedString[..<lowerBound])"
        }

        guard let date = dateFormatter.date(from: formattedString) else {
            return self
        }

        dateFormatter.dateFormat = "EEE, MMM d, yyyy - h:mm a"
        dateFormatter.timeZone = TimeZone.current
        return dateFormatter.string(from: date)
    }
}

为了提高效率，您可以使用迭代循环。

Answer 2

您的方法需要从子函数调用中返回名称的值

if(!m.matches()) {
    System.out.println("Invalid Name");
    return verifyName();
}

而不是

if(!m.matches()) {
    System.out.println("Invalid Name");
    verifyName();
}

然而，使用循环而不是递归调用可能更好：

public static String verifyName() {
    while (true)
    {
        System.out.print("Enter your name: ");
        String name = in.nextLine();
        Pattern p = Pattern.compile("[a-zA-Z0-9]*");
        Matcher m = p.matcher(name);
        if(m.matches()) {
           return name;
        }
    }

}

在java递归中返回变量的更新值

2 个答案: