How to sort a string as integer

Question

Hi,
I need to sort some log files which got timestamps as below:
1149807013000 this is line no 1
1149807023000 this is line no 2
I am converting the date time stamp of the log file to Date.getTime() in a ArrayList and then want to sort this so that i will get them sorted from oldest timestamp to new.
I am using Collections.sort(ArrayList) method, but it is sorting them as String. As this is simple array would it be possible to tell the sort program to sort as Numeric ?. I donot know how to write comparator for this kind of Array, any help here appreciated.
Thanks, Mani

Answer 1

I am posting my method here:
public static void sortLogs(ArrayList al, JTextArea txa){
        Date t;
        SimpleDateFormat formatter;       
        ArrayList al2=new ArrayList();
        for (int i=0;i < al.size();i++) {
            File file=new File(al.get(i).toString());
            if (file.exists()){
                if ( file.getName().startsWith("sys_log")){
                    //Jun 26 12:40:51 2006 BoxMonitor:3:526 enclosure 2 failed to respond to ping at management switch
                    //MMMsDDsTIMEsYR_data
                    try{
                        BufferedReader in=new BufferedReader(new FileReader(file));
                        String line=null;
                        formatter=new SimpleDateFormat("MMM dd HH:mm:ss yyyy",new Locale("en", "US"));
                        while ( (line=in.readLine())!=null){
                            Pattern p=Pattern.compile("^([JFMASOND][aepuco][nbrylgptvc])\\s+([\\d]+)\\s+([\\d]+[:][\\d]+[:][\\d]+)\\s+([\\d]+)\\s+(.*)");// \\s+(.*)");
                            Matcher m=p.matcher(line);
                            if (m.find()){
                                t=formatter.parse(m.group(1)+" "+m.group(2)+" "+m.group(3)+" "+m.group(4));
                                al2.add(t.getTime() + " "+file.getName()+" " + m.group(5));                               
                    }catch(Exception ex){
                        System.err.println("Error on file "+file.getPath()+ " error is "+ ex.getMessage());
        if ( al2.size() > 0) {
            t=new Date();
            formatter=new SimpleDateFormat("MMM dd HH:mm:ss yyyy",new Locale("en", "US"));
            Collections.sort(al2);    //once arraylist al2 is populated with all the files, want to sort which contains String lines like 102020000 filename data
            Pattern p=Pattern.compile("^(\\d+)\\s+(.*)");
            Matcher m;
            for (int j=0;j< al2.size();j++){
                m=p.matcher(al2.get(j).toString());                          
                if ( m.find()) {
                   t.setTime(Long.parseLong(m.group(1)));
                   txa.append(formatter.format(t)+" "+m.group(2)+"\n");                               
    }I am using Collections.sort. As you can see here i am perl guy trying to port my script to java. Was using unix sort on my perl script, but here i am stuck :-).
The ArrayList populated here from reading the text files - finding the date pattern - converting to ephoch seconds, and then i need to sort before converting back to normal date. When i verified the sort output, i see sorting like below:
1
100
2
20
where as in numeric i would like to see,
1
2
20
100
Thanks for your help.