detect file changes in Java without WatchService -

i created file checker checks file changes every x sec. problem if check file watchservice send modify event if touch file. can check file.lenght , if changes not change file size? there idea how can detect file changes?

this code( i'm using lastmodified() method while )

class checker implements runnable {  static logger log = logger.getlogger(monitor.class.getname()); private static final long default_check_interval = 5000; //5 sec private static simpledateformat dataformat = new simpledateformat("mm/dd/yyyy hh:mm:ss");     private file file; private long checkinterval;  public checker(string path, long checkinterval) throws exception {     this.file = new file(path);     this.checkinterval = checkinterval > 1000 ? checkinterval : default_check_interval; }  private jsonobject loadconfig() {     jsonobject conf = null;     try(bufferedreader reader = new bufferedreader(new filereader(this.file));) {          stringbuilder bldr = new stringbuilder((int) this.file.length());         string line = null;          while((line = reader.readline()) != null) {             bldr.append(line);         }          conf = new jsonobject(bldr.tostring());              thread.sleep(this.checkinterval);      } catch (exception e) {         log.error(e);     }     return conf; }     @override public void run() {     long moddate = 0;      while (true) {         long lastmodified = this.file.lastmodified();         jsonobject conf = loadconfig();         if (lastmodified != moddate) {             moddate = lastmodified;             log.warn("file changed @ " + dataformat.format(lastmodified));             log.info(conf.get("name") + ", " + conf.get("company"));                         }         log.info("no chenges");               }  } 

public class monitor {      public static void main(string[] args) throws exception {         new thread(new checker("/home/arno/test/config.json", 2000)).start();           } } 

maintain duplicate of file in other directory.

for instance have file on desktop, maintain copy of file in c: , check difference.

file source = new file(""c://desktop//filename.txt"); file dest = new file("c://temp//cache-filename.txt"); try {     fileutils.copydirectory(source, dest); } catch (ioexception e) {     e.printstacktrace(); } 

and maintain timer, call everytime.

timer timer = new timer(); timer.scheduleatfixedrate(new timertask() {   @override   public void run() {   if(comapretwofiles("c://temp//cache-filename.txt", "c://desktop//filename.txt")){     system.out.println("file changed");     //change cache file     }   } }, 2*60*1000, 2*60*1000); public boolean comparetwofiles(string path1, string path2)             throws ioexception {      file file1 = new file(path1);     file file2 = new file(path2);      bufferedreader br1 = new bufferedreader(new filereader(file1));     bufferedreader br2 = new bufferedreader(new filereader(file2));      string thisline = null;     string thatline = null;      list<string> list1 = new arraylist<string>();     list<string> list2 = new arraylist<string>();      while ((thisline = br1.readline()) != null) {         list1.add(thisline);     }     while ((thatline = br2.readline()) != null) {         list2.add(thatline);     }      br1.close();     br2.close();      return list1.equals(list2); }