Regex - removing duplicate matches

Question

I need to remove any duplicate matches from my regex pattern matcher so that only one occurrence of the match is output. Not sure how to go about this. Ive tried putting the values into a Set but duplicates were still output, it may be something as simple as ammending the Print Line statement or perhaps I need a for each loop somewhere but I think I have tried almost every possibility and cant get it to work! Any advice would be much appreciated, apologies if Ive missed something glaringly obvious!
import java.util.regex.*;
import java.io.*;
import java.util.*;
public class Tuesday {
public static void main(String[] args) throws IOException {
Pattern patt = Pattern.compile("VID_.{4}");
BufferedReader r = new BufferedReader(new FileReader("setupapi.log"));
String line;
while ((line = r.readLine()) != null) {
Matcher m = patt.matcher(line);
ArrayList retval = new ArrayList();
while (m.find()) {
//System.out.println(m.group(0));
// starting position of the text
int start = m.start(0);
// ending position
int end = m.end(0);
// CharacterIterator.substring(offset, end);
String tmp = (line.substring(start, end));
    if(retval.indexOf(tmp) == -1)
    retval.add(tmp);
System.out.println(retval);
}Output:
[VID_0930]
[VID_0930]
[VID_0930]
[VID_090C]
[VID_090C]
[VID_090C]
[VID_0A12]
[VID_0A12]
[VID_0A12]
[VID_0A12]
[VID_0A12]
[VID_0A17]
[VID_0A17]
[VID_0A17]

Answer 1

Thanks for your reply. This was how I did the set, again apologies if its something obvious that I have done wrong!
import java.util.Set;
import java.util.LinkedHashSet;
import java.util.HashSet;
import java.util.regex.*;
import java.io.*;
import java.util.*;
public class WithSet {
public static void main(String[] args) throws IOException {
Pattern patt = Pattern.compile("(VID_.{4})");
BufferedReader r = new BufferedReader(new FileReader("setupapi.log"));
String line;
while ((line = r.readLine()) != null) {
Matcher m = patt.matcher(line);
ArrayList retval = new ArrayList();
while (m.find()) {
retval.add(m.group());
HashSet set = new HashSet(retval);
//retval.clear();
//retval.addAll(set);
System.out.println(set);
}This is a sample of the log file:
[2008/01/25 20:35:54 664.3 Driver Install]
#-019 Searching for hardware ID(s): usb\vid_0930&pid_6534&rev_0100,usb\vid_0930&pid_6534
#-018 Searching for compatible ID(s): usb\class_08&subclass_06&prot_50,usb\class_08&subclass_06,usb\class_08
#-198 Command line processed: C:\WINDOWS\system32\services.exe
#I393 Modified INF cache "C:\WINDOWS\inf\INFCACHE.1".
#I022 Found "USB\Class_08&SubClass_06&Prot_50" in C:\WINDOWS\inf\usbstor.inf; Device: "USB Mass Storage Device"; Driver: "USB Mass Storage Device"; Provider: "Microsoft"; Mfg: "Compatible USB storage device"; Section name: "USBSTOR_BULK".
#I023 Actual install section: [USBSTOR_BULK.NT]. Rank: 0x00002000. Effective driver date: 07/01/2001.
#-166 Device install function: DIF_SELECTBESTCOMPATDRV.
#I063 Selected driver installs from section [USBSTOR_BULK] in "c:\windows\inf\usbstor.inf".
#I320 Class GUID of device remains: {36FC9E60-C465-11CF-8056-444553540000}.
#I060 Set selected driver.
#I058 Selected best compatible driver.
#-166 Device install function: DIF_INSTALLDEVICEFILES.
#I124 Doing copy-only install of "USB\VID_0930&PID_6534\5&719C62D&0&6".
#-166 Device install function: DIF_REGISTER_COINSTALLERS.
#I056 Coinstallers registered.
#-166 Device install function: DIF_INSTALLINTERFACES.
#-011 Installing section [USBSTOR_BULK.NT.Interfaces] from "c:\windows\inf\usbstor.inf".
#I054 Interfaces installed.
#-166 Device install function: DIF_INSTALLDEVICE.
#I123 Doing full install of "USB\VID_0930&PID_6534\5&719C62D&0&6".
#I121 Device install of "USB\VID_0930&PID_6534\5&719C62D&0&6" finished successfully.