CODEWITHSUNDEEP
javaregex
sunleo
sunleo

Reputation: 10943

how to check all character in a string is lowercase using java

I tried like this but it outputs false,Please help me

String inputString1 = "dfgh";// but not dFgH
String regex = "[a-z]";
boolean result;

Pattern pattern1 = Pattern.compile(regex);
Matcher matcher1 = pattern1.matcher(inputString1);
result = matcher1.matches();
System.out.println(result);

Upvotes: 9

Views: 29461

Answers (5)

Denys Séguret
Denys Séguret

Reputation: 382102

Use this pattern :

String regex = "[a-z]*";

Your current pattern only works if the tested string is one char only.

Note that it does exactly what it looks like : it doesn't really test if the string is in lowercase but if it doesn't contain chars outside [a-z]. This means it returns false for lowercase strings like "àbcd". A correct solution in a Unicode world would be to use the Character.isLowercase() function and loop over the string.

Upvotes: 3

Robin
Robin

Reputation: 36601

Why bother with a regular expression ?

String inputString1 = "dfgh";// but not dFgH
boolean result = inputString1.toLowerCase().equals( inputString1 );

Upvotes: 0

PermGenError
PermGenError

Reputation: 46408

you are almost there, except that you are only checking for one character.

String regex = "[a-z]+";

the above regex would check if the input string would contain any number of characters from a to z

read about how to use Quantifiers in regex

Upvotes: 5

Marko Topolnik
Marko Topolnik

Reputation: 200148

Your solution is nearly correct. The regex must say "[a-z]+"—include a quantifier, which means that you are not matching a single character, but one or more lowercase characters. Note that the uber-correct solution, which matches any lowercase char in Unicode, and not only those from the English alphabet, is this:

"\\p{javaLowerCase}+"

Additionally note that you can achieve this with much less code:

System.out.println(input.matches("\\p{javaLowerCase}*"));

(here I am alternatively using the * quantifier, which means zero or more. Choose according to the desired semantics.)

Upvotes: 22

Anirudha
Anirudha

Reputation: 32787

It should be

^[a-z]+$

^ is the start of string

$ is the end of string

[a-z]+ matches 1 to many small characters

You need to use quantifies like * which matches 0 to many chars,+ which matches 1 to many chars..They would matches 0 or 1 to many times of the preceding character or range

Upvotes: 2

Related Questions