Let's check ip addresses in Java with regex
- First of all we need to import 2 library.
import java.util.regex.Matcher;
import java.util.regex.Pattern;
- Now, lets define ip regex
public static final String IP_REGEX ="^"
+ "([01]?\\d\\d?|2[0-4]\\d|22[0-3])\\."
+ "([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\."
+ "([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\."
+ "([01]?\\d\\d?|2[0-4]\\d|25[0-4])$";
^ -->start of the line
( --> start of group #1
[01]?\d\d? --> Can be one or two digits. If three digits appear, it must start either 0 or 1
# e.g ([0-9], [0-9][0-9],[0-1][0-9][0-9])
| --> or
2[0-4]\d # start with 2, follow by 0-4 and end with any digit (2[0-4][0-9])
| --> or
25[0-5] # start with 2, follow by 5 and ends with 0-5 (25[0-5])
) --> end of group #2
. --> follow by a dot "."
.... --> repeat with 3 times (3x)
$ -->end of the line
- Create an pattern object and pass regex string to it.
String ipregex = System.console().readLine(); //read input
Pattern ipPattern= Pattern.compile(IP_REGEX);
Matcher ipMatcher = ipPattern.matcher(ipregex);
- Finally we can control our result.
//Control flow
if (!ipMatcher.matches()) {
System.out.println("Yay ! ");
}
else{
System.out.println("Noooooo! ");
}
return ipregex;
Top comments (0)