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javaregexcharacter-properties

Java: Validate textfield input if it only contains alphabetic characters

How do I validate if a text only contains alphabetic characters?

I think we can use Pattern.matches() but I don't know the regular expression for alphabetic characters.

Solution

  • Use a category for alphabetics, combined with matches, and delimiters for the beginning and end of input text, as such: 

    String valid = "abc";
String invalid = "abc3";
Pattern pattern = Pattern.compile("^\\p{Alpha}+$"); // use \\p{L} for Unicode support
Matcher matcher = pattern.matcher(valid);
System.out.println(matcher.matches());
matcher = pattern.matcher(invalid);
System.out.println(matcher.matches());

    Output: 

    true
false

    Note: this also happens to prevent empty inputs. If you want to allow them, use a different quantifier than +, namely, *.

    Finally, since you will use that against a java.awt.TextField, you can simply access its text with the method getText().