在Java中无法检查密码的方法

Question

I'm trying to write a method that returns if the string is or isn't a valid password in CodeHS.

It needs to be at least eight characters long and can only have letters and digits.

In the grader, it passes every test except for passwordCheck("codingisawesome") and passwordCheck("QWERTYUIOP") .

Here's what I have so far:

public boolean passwordCheck(String password)
{
    if (password.length() < 8)
    {
        return false;  
    }
    else 
    {  
        char c;  
        int count = 0;   
        for (int i = 0; i < password.length(); i++) 
        {
            c = password.charAt(i);  
            if (!Character.isLetterOrDigit(c)) 
            {
                return false;  
            } else if (Character.isDigit(c)) 
            {
                count++;     
            }
        }
        if (count < 2)
        {  
            return false;  
        }
    }
    return true;  
}

If anyone can help, I'd appreciate it. Thanks.

Answer 1

Try an approach using patterns (this is simpler than looping):

public boolean passwordCheck(String password)
{
    return password!=null && password.length()>=8 && password.matches("[A-Za-z0-9]*");
}

Decent tutorial on regular expressions (that's where the AZ magic comes from): http://www.vogella.com/tutorials/JavaRegularExpressions/article.html

Answer 2

Assuming your requirement is as stated

It needs to be at least eight characters long and can only have letters and digits

Then there is no need to count digits. Simply check that the password is the minimum length, then loop over every character returning false if any are not a letter or digit. Like,

public boolean passwordCheck(String password) {
    if (password != null && password.length() >= 8) {
        for (char ch : password.toCharArray()) {
            if (!Character.isLetterOrDigit(ch)) {
                return false;
            }
        }
        return true;
    }
    return false;
}

Answer 3

It's failing those tests because your code checks that the password must have at least 2 digits:-

 if (count < 2) { return false; } 

And your test strings don't have any. Remove this piece of code and it should work. For a better way of doing it, see other answers.