Using RegEx to achieve the following

Question

Here is what I want to achieve:
INPUT:
access-list 99 permit 172.0.0.0 0.255.255.255
access-list 99 permit 192.168.0.0 0.0.255.255
access-list 99 deny any
snmp-server community Cust1 RO 99
snmp-server community Cust1-RW RW 99
snmp-server community Cust1-RW RW 100
The intent is to find the any snmp-server line that has a number at the end which is not defined in the above set of lines. In the above example we should be able to find the last line.
How can we do this in pure java regex.
I highly appreciate any response on this.
Thanks
Sanjeev

Answer 1

Hi,
I don't know what you mean by "pure java regex". But you could try it with something like this:
import java.io.BufferedReader;
import java.io.FileReader;
import java.util.HashSet;
import java.util.Iterator;
import java.util.regex.Pattern;
import java.util.regex.Matcher;
class RegEx {
    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new FileReader("file.txt"));
        String line;
        HashSet set = new HashSet();
        Pattern p1 = Pattern.compile("access-list (\\d*) .*");
        while ((line=br.readLine()) != null) {
            Matcher m = p1.matcher(line);
            if (m.find()) {
                String number = m.group(1);
                if (!set.contains(number)) {
                    set.add(number);
        br.close();
        br = new BufferedReader(new FileReader("file.txt"));
        StringBuffer sb = new StringBuffer();
        Iterator iter = set.iterator();
        if (iter.hasNext()) {
            sb.append(iter.next().toString());
        for ( ; iter.hasNext(); ) {
            sb.append("|");
            sb.append(iter.next().toString());
        String regex = "snmp-server.* " + sb.toString() + "$";
        Pattern p = Pattern.compile(regex);
        while ((line=br.readLine()) != null) {
            if (line.startsWith("snmp-server")) {
                Matcher m = p.matcher(line);
                if (!m.find()) {
                    System.out.println(line);
}Stefan