java - do while 循环中正确循环的问题 - Java

Question

我的程序似乎存在一些问题。我的导师建议我使用 do while 循环来保持程序运行。但是，当我输入无效密码并重新启动时，它会出错。当我输入有效密码时，它仅打印“有效密码”并且不循环。我哪里出错了？

import java.util.Scanner;

public class CovenduniteProg5_FIX {

    public static void main(String[] args)      {
        boolean passwordValid = false;

        do  {
            boolean invalidLength = false;
            boolean containsRestrictedWord = false;
            boolean containsLowerCaseLetter = false;
            boolean containsUpperCaseLetter = false;
            boolean containsDigit = false;
            boolean containsSpecialChar = false;

            Scanner stdIn = new Scanner(System.in);

            System.out.println("Password Verifier"); 
            System.out.println("\nEnter a password that meets the following rules:\n" +
                "\tIs at least 8 characters long\n" + 
                "\tContains at least 1 lower letter character\n" +
                "\tContains at least 1 upper letter character\n" +
                "\tContains at least 1 numberic digit\n" +
                "\tContains at least 1 special character from the set: !@#$%^&*\n" +
                "\tDoes not contain the word \"and\" or the word \"the\"\n");
            System.out.print("Enter your password: ");
            String password = stdIn.nextLine();

            for (int i = 0; i < password.length(); i++) {
                char ch = password.charAt(i);

                if (Character.isUpperCase(ch) && !containsUpperCaseLetter) {
                    containsUpperCaseLetter = true;
                }

                if (Character.isLowerCase(ch) && !containsLowerCaseLetter) {
                    containsLowerCaseLetter = true;
                }

                if (Character.isDigit(ch) && !containsDigit) {
                    containsDigit = true;
                }

                if ((ch == '!' || ch == '@' || ch == '#' || ch == '$' || ch == '%' || ch == '^' || ch == '&' || ch == '*') && !containsSpecialChar) {
                    containsSpecialChar = true;
                }
            }

            if (password.length() < 8 ) {
                invalidLength = true;
            } 

            if (password.contains("and") || password.contains("the")) {
                containsRestrictedWord = true;
            }

            if (invalidLength) {
                System.out.println("Invalid: Invalid length");
            }

            if (containsRestrictedWord) {
                System.out.println("Invalid: Contains either the word \"and\" or \"the\".");
            }

            if (!containsDigit) {
                System.out.println("Invalid: Does not contain at least one digit.");
            }

            if (!containsLowerCaseLetter) {
                System.out.println("Invalid: Does not contain at least one lowercase letter.");
            }

            if (!containsUpperCaseLetter) {
                System.out.println("Invalid: Does not contain at least one uppercase letter.");
            }

            if(!containsSpecialChar) {
                System.out.println("Invalid: Does not contain at least one special character.");
            }

            if (containsSpecialChar && containsUpperCaseLetter && containsLowerCaseLetter && containsDigit && !containsRestrictedWord && !invalidLength)
                passwordValid = true;

            if (passwordValid)
                System.out.print("\nPassword is valid.");

        } while (!passwordValid);

        passwordValid = false;

        while(!passwordValid) {
            if (passwordValid)
                System.out.print("\nPassword is valid.");
        }
    }
}

Answer 1

我们不需要第二个 while 循环，它基本上是一个无限循环。此外，我们需要将“密码 validator ”语句移到 while 循环之外，因为它们不需要多次打印。因此，该方法将如下所示:

public static void main(String[] args) {

    boolean passwordValid = false;
    System.out.println("Password Verifier");
    System.out.println("\nEnter a password that meets the following rules:\n" + "\tIs at least 8 characters long\n"
            + "\tContains at least 1 lower letter character\n" + "\tContains at least 1 upper letter character\n"
            + "\tContains at least 1 numberic digit\n"
            + "\tContains at least 1 special character from the set: !@#$%^&*\n"
            + "\tDoes not contain the word \"and\" or the word \"the\"\n");
    do {
        boolean invalidLength = false;
        boolean containsRestrictedWord = false;
        boolean containsLowerCaseLetter = false;
        boolean containsUpperCaseLetter = false;
        boolean containsDigit = false;
        boolean containsSpecialChar = false;

        Scanner stdIn = new Scanner(System.in);

        System.out.print("Enter your password: ");
        String password = stdIn.nextLine();

        for (int i = 0; i < password.length(); i++) {
            char ch = password.charAt(i);

            if (Character.isUpperCase(ch) && !containsUpperCaseLetter) {
                containsUpperCaseLetter = true;
            }

            if (Character.isLowerCase(ch) && !containsLowerCaseLetter) {
                containsLowerCaseLetter = true;
            }

            if (Character.isDigit(ch) && !containsDigit) {
                containsDigit = true;
            }

            if ((ch == '!' || ch == '@' || ch == '#' || ch == '$' || ch == '%' || ch == '^' || ch == '&'
                    || ch == '*') && !containsSpecialChar) {
                containsSpecialChar = true;
            }
        }

        if (password.length() < 8) {
            invalidLength = true;
        }

        if (password.contains("and") || password.contains("the")) {
            containsRestrictedWord = true;
        }

        if (invalidLength) {
            System.out.println("Invalid: Invalid length");
        }

        if (containsRestrictedWord) {
            System.out.println("Invalid: Contains either the word \"and\" or \"the\".");
        }

        if (!containsDigit) {
            System.out.println("Invalid: Does not contain at least one digit.");
        }

        if (!containsLowerCaseLetter) {
            System.out.println("Invalid: Does not contain at least one lowercase letter.");
        }

        if (!containsUpperCaseLetter) {
            System.out.println("Invalid: Does not contain at least one uppercase letter.");
        }

        if (!containsSpecialChar) {
            System.out.println("Invalid: Does not contain at least one special character.");
        }

        if (containsSpecialChar && containsUpperCaseLetter && containsLowerCaseLetter && containsDigit
                && !containsRestrictedWord && !invalidLength)
            passwordValid = true;

        if (passwordValid)
            System.out.print("\nPassword is valid.");

    } while (!passwordValid);
}