CODEWITHSUNDEEP
javaregex
KisnardOnline
KisnardOnline

Reputation: 740

java regex for alpha and spaces is including [ ] \

This is my regex for my JTextField to not be longer than x characters and to not include anything other than letters or spaces. For some reason it is allowing [ ] and \ characters. This is driving me crazy. Is my regex wrong??

package com.jayavon.game.helper;

import java.awt.Toolkit;

import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;

public class CharacterNameCreationDocument extends PlainDocument {
    private static final long serialVersionUID = 1L;
    private int limit;

    public CharacterNameCreationDocument(int limit) {
        super();
        this.limit = limit;
    }

    public void insertString(int offset, String  str, AttributeSet attr) throws BadLocationException {
        if (str == null || (getLength() + str.length()) > limit || !str.matches("[a-zA-z\\s]*")){
            Toolkit.getDefaultToolkit().beep();
            return;
        } else {
            super.insertString(offset, str, attr);
        }
    }
}

Upvotes: 3

Views: 23615

Answers (3)

Alan Moore
Alan Moore

Reputation: 75222

You have a typo in your regex:

"[a-zA-z\\s]*"

[A-z] matches all the uppercase and lowercase letters plus [, ], ^, _, backslash and backtick, whose code points happen to lie between Z and a.

Also, I agree with @Ωmega that you probably should be using an actual space character instead of \s:

"[a-zA-Z ]*"

The anchors (^ and $) aren't necessary since you're using the matches() method, which automatically anchors the match at both ends. They don't hurt anything though, and they do help communicate your intent.

Upvotes: 8

Ωmega
Ωmega

Reputation: 43673

You should use regex pattern 

^[a-zA-Z\\s]*$

where ^ is start of string and $ represents end of string.

You can also extend such regex to check the string size. Let's say if you want allow minimum 5 characters and maximum 20 characters

^[a-zA-Z\\s]{5,20}$

However, because whitespace \\s can be not just space-bar character, but also other charactes, such as new-line, tab, etc., you may want to limit this just to real space-bar characters using

 ^[a-zA-Z ]{5,20}$

Additionaly, you might want to limit multiple space characters to be used in sequence. If so, use

^(?!.* {2,})[a-zA-Z ]{5,20}$`

You might want string always to start and end with non-space characters. To add such feature go with

^(?=.{5,20}$)(?!.* {2,})[a-zA-Z][a-zA-Z ]*[a-zA-Z]$

Upvotes: 7

John Woo
John Woo

Reputation: 263713

reformat your regex into this: 

^[A-Za-z\\s]{0,3}$

just change 3 to your desired length.

Upvotes: 1

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