do whileループで適切なループが発生する問題 - Java

Question

私のプログラムにいくつか問題があるようです。インストラクターがdo whileループを使用してプログラムを実行し続けることを勧めました。しかし、無効なパスワードを入力して再起動するとエラーになります。有効なパスワードを入力すると、「有効なパスワード」のみが表示され、ではなく、ループになります。どこが間違っていたのですか？

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

あなただけのループの前に一度それを持っていなければならないときは、do-while外の最後passwordValid = false;を置きます。それは基本的にinfinite loopだ、私たちは二whileループを必要としない

boolean passwordValid = false; //← only here 
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); 

    /* 

    ... 

    */ 

    if (/*All sub-conditions met*/) 
     passwordValid = true; 

    if (passwordValid) 
     System.out.print("\nPassword is valid."); 
} 
while (!passwordValid); 
//passwordValid = false; ← remove this 

//no need for while or if statment, because you can only reach this code if passwordValid = true 
System.out.print("\nPassword is valid."); 

Answer 2

：そして、あなたはまた、第二while(!passwordValid)ループを必要としません。また、「Password Verifier」ステートメントは、複数回印刷する必要がないため、whileループの外側に移動する必要があります。したがって、メソッドは次のようになります。

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); 
} 

Answer 3

次のコードは、あなたが求めていることを行います。考慮する必要があるもの：

• 2番目のwhileループは無限です。
• doループの外でスキャナを宣言してください...毎回作成すると問題が発生する可能性があり、一度だけ宣言して作成する必要があります。
• 2つのdoループを使用すると、外側のループは無限の状態になりますので、永遠に続きます...何らかの方法で終了するように書き直すことができます。
• 外部ループはメニューを表示します。
• 内側のループはすべてあなたのスキャナ/入力と検証と判定を行います。

希望これは

// CovenduniteProg5_FIX 
public static void main(String[] args) { 
    boolean passwordValid = false; 
    Scanner stdIn = new Scanner(System.in); 

    do { 
     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: "); 

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

      try { 
       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."); 

      } 
      catch (Exception ltheXcp) { 
       ltheXcp.printStackTrace(); 
      } 
     } while (!passwordValid); 

     passwordValid = false; 

    } while (1 != 2); 

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