Java reading long text file is very slow -

i have text file (xml created xstream) 63000 lines (3.5 mb) long. i'm trying read using buffered reader:

                bufferedreader br = new bufferedreader(new filereader(file));                 try {                     string s = "";                     string tempstring;                     int = 0;                     while ((tempstring = br.readline()) != null) {                         s = s.concat(tempstring); //                        s=s+tempstring;                         = + 1;                         if (i % 1000 == 0) {                             system.out.println(integer.tostring(i));                         }                     }                     br.close(); 

here can see attempts measure reading speed. , it's low. takes seconds read 1000 lines after 10000 line. i'm doing wrong, can't understand what. in advance help.

@paulgrime right. copying string each time loop reads line. once string gets big (say 10,000 lines big), doing lot of work copying.

try this:

stringbuilder sb = new stringbuilder(); while (...reading lines..){     ....    sb.append(tempstring);  //should add newline    ... }  s = sb.tostring(); 

note: read paul's answer below on why stripping newlines makes bad way read in file. also, mentioned in question comments, xstream provides way read file , if had not, ioutils.tostring(reader) safer way read file.