如何创建一个 Java 程序来检查您的密码是否强？
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How to create a Java program to check if your password is strong or not?
提问by shreydan
I want the program to do 2 things:
我希望程序做两件事：
- Check if the string(password input) contains both letters and numbers.
- Check if the password has atleast 8 characters.
- 检查字符串（密码输入）是否同时包含字母和数字。
- 检查密码是否至少有 8 个字符。
Here is my code:
这是我的代码：
import java.util.*;
class howstrong
{
public static void main(String ar[])
{
String password;
int i;
int c=0;
Scanner in = new Scanner(System.in);
System.out.println("ENTER PASSWORD");
password = in.next();
if (password.length() <= 8)
{
for (i = 0; i <= password.length(); i++)
{
char x = password.charAt(i);
if (Character.isLetter(x))
{
if (Character.isDigit(x))
c = 1;
}
}
if (c == 1)
System.out.println("STRONG");
else
System.out.println("NOT STRONG");
}
else
System.out.println("HAVE AT LEAST 8 CHARACTERS");
}
}
回答by Arnaud
You have several issues :
你有几个问题：
i <= password.length()should be i < password.length()
i <= password.length()应该 i < password.length()
if (password.length() <= 8)should be if (password.length() >= 8)
if (password.length() <= 8)应该 if (password.length() >= 8)
You are checking if the character is a letter and a digit at the same time.
您正在检查字符是否同时是字母和数字。
Finally, I'd suggest to use two flags, one to detect if there is a letter, another one to detect if there is a digit .
最后，我建议使用两个标志，一个用于检测是否有字母，另一个用于检测是否有 digit 。
Putting it all together :
把它们放在一起：
import java.util.Scanner;
class howstrong {
public static void main(final String ar[]) {
String password;
Scanner in = new Scanner(System.in);
System.out.println("ENTER PASSWORD");
password = in.next();
boolean hasLetter = false;
boolean hasDigit = false;
if (password.length() >= 8) {
for (int i = 0; i < password.length(); i++) {
char x = password.charAt(i);
if (Character.isLetter(x)) {
hasLetter = true;
}
else if (Character.isDigit(x)) {
hasDigit = true;
}
// no need to check further, break the loop
if(hasLetter && hasDigit){
break;
}
}
if (hasLetter && hasDigit) {
System.out.println("STRONG");
} else {
System.out.println("NOT STRONG");
}
} else {
System.out.println("HAVE AT LEAST 8 CHARACTERS");
}
}
}
回答by ishmaelMakitla
there is a Regex expression that you could use to check password strength. You could add a validation method that checks if the password matches the expression: So you call the method in your code like this:
您可以使用正则表达式来检查密码强度。您可以添加一个验证方法来检查密码是否与表达式匹配：因此您可以像这样在代码中调用该方法：
password = in.next();
if(isStrong(password){
//good password, do stuff
}
else{
//not so good, prompt again
}
And the method looks like this:
该方法如下所示：
private boolean isStrong(String password){
return password.matches("^(?=.*[A-Z].*[A-Z])(?=.*[!@#$&*])(?=.*[0-9].*[0-9])(?=.*[a-z].*[a-z].*[a-z])");
}
Below is a regex which you can use to check password strength.
下面是一个正则表达式，您可以使用它来检查密码强度。
^(?=.*[A-Z].*[A-Z])(?=.*[!@#$&*])(?=.*[0-9].*[0-9])(?=.*[a-z].*[a-z].*[a-z]).{8}$
You can look at the original post and selected answer here.
您可以在此处查看原始帖子和选定的答案。
回答by Julien Lopez
In your loop, you check if your character is a letter anda digit. So cwill never be set to 1. I suggest you learn to use a debugger, it will help you solve this kind of bugs easily.
在你的循环中，你检查你的字符是否是一个字母和一个数字。所以c永远不会设置为1。我建议你学会使用调试器，它会帮助你轻松解决此类错误。
回答by xcesco
I don't know, because it not specified, if your need it just for exercise or you need to implements in a real world application.
我不知道，因为它没有指定，如果你只是为了练习而需要它，或者你需要在现实世界的应用程序中实现。
In the second case, I suggest you to use an existing library to check if a password is strong enough.
在第二种情况下，我建议您使用现有的库来检查密码是否足够强。
Check zxcvbn Java version on github, that is a porting of a library provided by Dropbox.
检查github 上的 zxcvbn Java 版本，这是 Dropbox 提供的库的移植。
