Question

我正在尝试用Java创建一个检查三个特定输入的程序。它必须通过这些测试：

至少7个字符。
包含upper和lower个字母字符。
至少包含1数字。

到目前为止，我已经能够检查是否有7个字符，但我遇到了最后两个问题。作为if语句，我应该在循环中放入什么来检查数字并使其成为大写和小写。任何帮助将不胜感激。这是我到目前为止所拥有的。

import java.awt.*;
import java.io.*;
import java.util.StringTokenizer;

public class passCheck
{


    private static String getStrSys ()
    {
        String myInput = null;          //Store the String that is read in from the command line

        BufferedReader mySystem;        //Buffer to store the input

        mySystem = new BufferedReader (new InputStreamReader (System.in)); //creates a connection to system input
        try
        {
            myInput = mySystem.readLine (); //reads in data from the console
            myInput = myInput.trim ();
        }
        catch (IOException e)  //check
        {
            System.out.println ("IOException: " + e);
            return "";
        }
        return myInput; //return the integer to the main program
    }


    //****************************************
    //main instructions go here
    //****************************************

    static public void main (String[] args)
    {

        String pass;         //the words the user inputs
        String temp = "";            //holds temp info

        int stringLength;          //length of string
        boolean goodPass = false;


        System.out.print ("Please enter a password: ");  //ask for words

        pass = getStrSys ();                              //get words from system
        temp = pass.toLowerCase ();
        stringLength = pass.length ();             //find length of eveyrthing



        while (goodPass == false)

            {
                if (stringLength < 7)
                {
                    System.out.println ("Your password must consist of at least 7 characters");
                    System.out.print ("Please enter a password: ");  //ask for words
                    pass = getStrSys ();
                    stringLength = pass.length ();
                    goodPass = false;
                }
                else if (/* something to check for digits */)
                {

                }

            }

Answer 1

当然，你可以提出一个令人费解的几乎不可读的 -regex这样做，但我不建议。除了可读性方面，如果密码失败，它不会告诉您原因。这解决了这两个问题：

while (true) {
  pass = getStrSys();
  if (pass.length() < 7) {
    System.out.println("must be at least 7 characters long");
  } else {
    boolean upper = false;
    boolean lower = false;
    boolean number = false;
    for (char c : pass.toCharArray()) {
      if (Character.isUpperCase(c)) {
        upper = true;
      } else if (Character.isLowerCase(c)) {
        lower = true;
      } else if (Character.isDigit(c)) {
        number = true;
      }
    }
    if (!upper) {
      System.out.println("must contain at least one uppercase character");
    } else if (!lower) {
      System.out.println("must contain at least one lowercase character");
    } else if (!number) {
      System.out.println("must contain at least one number");
    } else {
      break;
    }
  }
}

Answer 2

正则表达式更适合您要完成的任务。例如，使用lookahead assertions，您可以使用以下内容：

Pattern p = Pattern.compile("^.*(?=.{7,})(?=.*[a-z])(?=.*[A-Z])(?=.*[0-9]).*$");
String pass = getStrSys();
Matcher m = p.matcher(pass);
if (m.matches()) {
  System.out.println("Valid password.");
} else {
  System.out.println("Invalid password.");
}

Answer 3

不要使用StringTokenizer。使用String.split。
使用Character类中的函数检查大写，小写或数字。
由于你强迫小写，你无法检查。你需要摆脱它。

Answer 4

在你的情况下。验证应该有两个条件成立。我认为以下将是实现它的最佳方法。

private static final char[] SPECIAL = "$!+\-#?_%&/".toCharArray();
private static final char[] NUMBER = "0123456789".toCharArray();


public static boolean checkValidation(String password)
{
    int points = 0;
    String lowerPass = password.toLowerCase();
    String upperPass = password.toUpperCase();
    if(!password.equals(lowerPass) && !password.equals(upperPass))
    {
        // if contains upper or lower letter
        points++;
    }

    if(contains(password, SPECIAL))
    {
        // if it contains special character
        points++;
    }
    if(contains(password, NUMBER))
    {
        // if it contains Number
        points++;
    }

    return points >= 2;
}


public static boolean contains(String pwd, char[] value)
{
    int i = 0;
    boolean success = false;
    while(i < value.length && !success)
    {
        if(pwd.indexOf(""+value[i]) != -1)
        {
            success = true;
        }
        i++;
    }
    return success;
}

帮助在java中创建密码检查器

4 个答案: