I am trying to check whether a password is alphanumeric or not using regex but I am not getting the result I expect. What is the problem with the below code?
boolean passwordOnlyAlphaNumericCheck = false;
Pattern patternAlphaNumericCheck = Pattern.compile("^[a-zA-Z0-9]$");
Matcher matcherAlphaNumericCheck = patternAlphaNumericCheck.matcher(login.getPassword());
if(matcherAlphaNumericCheck.find())
passwordOnlyAlphaNumericCheck = true;
Thanks for help
You need to add a quantifier that suits your requirements: * - 0 or more occurrences or + - 1 or more occurrences. You can also omit the ^ and $ and use String.matches():
boolean passwordOnlyAlphaNumericCheck = false;
if(login.getPassword().matches("[a-zA-Z0-9]*"))
passwordOnlyAlphaNumericCheck = true;
To match all Unicode letters, use \p{L} class (and perhaps, \p{M} to match diacritics): "[\\p{L}\\p{M}0-9]+".
what is the difference between
login.getPassword().matches("[0-9a-zA-Z]*");andlogin.getPassword().matches("[0-9a-zA-Z]");?
The .matches("[0-9a-zA-Z]") will only return true if the whole string contains just 1 digit or letter. The * in [0-9a-zA-Z]* will allow an empty string, or a string having zero or more letters/digits.
use this regex expression Take a Demo Here For Regex
"^[a-zA-Z0-9]*$ " Or "^[a-zA-Z0-9]+$"
instead of
"^[a-zA-Z0-9]$ // * or + should be added at last
So, This might work to you
Pattern patternAlphaNumericCheck = Pattern.compile("^[a-zA-Z0-9]*$");
OR
Pattern patternAlphaNumericCheck = Pattern.compile("^[a-zA-Z0-9]+$");
Your pattern will only match strings with one alphanumeric character, since you have no quantifier and match explicitly from start (^) to end ($).
Append + for 1+ matches, or * for 0+ matches to your character class.
You can also use the script: \\p{Alnum} instead of a tedious character class.
For instance:
^\\p{Alnum}{8}$ will match a String made of 8 alphanumeric characters^\\p{Alnum}{8,}$ will match a String made of 8 or more alphanumeric characters^\\p{Alnum}{8,10}$ will match a String made of 8 to 10 alphanumeric characters^\\p{Alnum}+$ will match a String made of 1 or more alnums^\\p{Alnum}*$ will match an empty String or a String made of any number of alnumsThis function will help ensure that you have just alphanumeric as wanted.
public static boolean isAlphanumeric(String value){
if (isValueEmpty(value)) {
return false;
}
return value.matches("^[a-zA-Z_0-9]*$");
}
public static boolean isValueEmpty(String param){
return param == null || param.isEmpty();
}
Try this regexp:
private final String nonAlphanumericRegex = ".*\\W.*";
if (Pattern.matches(nonAlphanumericRegex, YOUR_STRING))
throw IllegalArgumentException()
"^[a-zA-Z0-9]+$"or"^[a-zA-Z0-9]*"- you forgot the quantifier. And you can remove the^and$and use.matches().login.getPassword().matches("[0-9a-zA-Z]*");but what is the difference betweenlogin.getPassword().matches("[0-9a-zA-Z]*");andlogin.getPassword().matches("[0-9a-zA-Z]");