Java: Validate textfield input if it only contains alphabetic characters

Question

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.

Answer 1

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().

Answer 2

It would be better if you used JFormattedTextField

here's more info in it: http://docs.oracle.com/javase/7/docs/api/javax/swing/JFormattedTextField.html