uniqueidentifier - Creating a unique filename from a list of alphanumeric strings -

i apologize creating similar thread many out there now, wanted insight on methods.

i have list of strings (could 1 or on 1000) format = xxx-xxxxx-xx each 1 alphanumeric

i trying generate unique string (currently 18 in length longer ensuring not maximize file length or path length) reproduce if have same list. order doesn't matter; although may interested if easier restrict order well.

my current java code follows (which failed today, hence why here):

 public string createoutputfilename(arraylist alinput, enumfpfunction efpf, boolean pheaders) {     /* create file name based on input list */     string sfilename = "";     long partnum = 0;      (string sgpn : alinput) {         sgpn = sgpn.replaceall("-", ""); //remove dashes         partnum += long.parselong(sgpn, 36);    //(base 36)     }     sfilename = long.tostring(partnum);     if (sfilename.length() > 19) {         sfilename.substring(0, 18); //max length of 19     }     return alinput; } 

so adding them did not work out found out (also think should take last 18 digits , not first 18)

are there methods out there (possibly crc related) work?

to assist key creation: first 3 characters numeric , have many duplicate (out of 100, there may 10 different starting numbers) these characters not allowed - i,o there never character number in last 2 alphachar subset.

i use system time. here's how might in java:

public string createoutputfilename() {     long mills = system.currenttimemillis();     long nanos = system.nanotime();     return mills + " " + nanos; } 

if want add information items , part numbers, can, of course!

======== edit: "what mean batch object" =========

class batch {      arraylist<item> itemstoprocess;     string inputfilename; // input external process     boolean processingfinished;      public batch(arraylist<item> itemstoprocess) {         this.itemstoprocess = itemstoprocess;         inputfilename = null;         processingfinished = false;     }      public void processwithexternal() {         if(inputfilename != null || processingfinished) {             throw new illegalstateexception("cannot initiate process more once!");         }         string base = system.currenttimemillis() + " " + system.nanotime();         this.inputfilename = base + "_input";          writeitemstofile();          // build process, here         process p = new processbuilder("myprocess","myargs", inputfilename);          p.start();         p.waitfor();         processingfinished = true;     }      private void writeitemstofile() {         printwriter out = new printwriter(new bufferedwriter(new filewriter(inputfilename)));         int flushcount = 0;         for(item item : itemstoprocess) {             string output = item.getfilerepresentation();             out.println(output);             if(++flushcount % 10 == 0) out.flush();         }         out.flush();         out.close();     }  }