第六章第十八题（检测密码）(Check password)

第六章第十八题（检测密码）(Check password)

• **6.18（检测密码）一些网站对于密码具有一些规则。编写一个方法，检测字符串是否是一个有效密码。假定密码规则如下：
  密码必须至少8位字符。
  密码仅能包含字母和数字。
  密码必须包含至少两个数字。
  编写一个程序，提示用户输入一个密码，如果符合规则，则显示Valid Password,否则显示Invalid Password。
  **6.18(Check password) Some websites impose certain rules for passwords. Write a method that checks whether a string is a valid password. Suppose the password rules are as follows:
  A password must have at least eight characters.
  A password consists of only letters and digits.
  A password must contain at least two digits.
  Write a program that prompts the user to enter a password and displays Valid Password if the rules are followed or Invalid Password otherwise.
• 参考代码：

package chapter06;

import java.util.Scanner;

public class Code_18 {
    
    
    public static void main(String[] args) {
    
    
        Scanner input = new Scanner(System.in);
        System.out.print("Enter a string: ");
        String str = input.nextLine();
        if (passwordTestLength(str) && passwordTestLetterOrDigit(str) && passwordTestNumber(str))
            System.out.println("Valid Password");
        else
            System.out.println("Invalid Password");
    }
    public static boolean passwordTestLength(String str){
    
    
        if (str.length() >= 8)
            return true;
        else return false;
    }
    public static boolean passwordTestLetterOrDigit(String str){
    
    
        for (int i = 0;i < str.length();i++){
    
    
            if (!Character.isLetterOrDigit(str.charAt(i)))
                return false;
        }
        return true;
    }
    public static boolean passwordTestNumber(String str){
    
    
        int number = 0;
        for (int i = 0;i < str.length();i++){
    
    
            if (Character.isDigit(str.charAt(i)))
                number++;
        }
        if (number >= 2)
            return true;
        return false;
    }
}

• 结果显示：

Enter a string: jxh1025
Invalid Password

Process finished with exit code 0