Question

I have a EditText in android where IP Address is supposed to be entered. On click of a button I want to check if the text retrieved from EditText does :

• not have any spaces
• not have any letters

• not empty

• contain only numbers

• and contain only periods "."

I have this if else condition to check if the user is allowed to go to the next activity but it still has some bugs. I don’t know how to allow ONLY periods

                    if(((ip.length() != 0) || ip.contains(" ") == false || ip.matches("[a-z]+") == false) && (ip.matches("[0-9]+") && ip.contains(".")))
                    {
                        next = false;
                    }
                    else
                    {
                        next = true;
                    }

Answer 1

You can use this regex to check the input

"^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$"

EDIT:

Do not use regex as things will break when IPv6 comes, use this instead

http://commons.apache.org/validator/apidocs/org/apache/commons/validator/routines/InetAddressValidator.html