Android/Java - Random Read line not changing -

my text file contains known number of lines (the first line of file number of lines). want randomly read line file - use linenumberreader. problem is, doesn't generate new string - random number changes string gets linenumberreader doesn't.

as title implies android app. textbox output area, testbox debugging (in code displays random number - check has changed) , r random

this sample code onclick button in app.

           string filename = "\\sdcard\\q's.txt";    try {        bufferedreader br = new bufferedreader(                new inputstreamreader(                        new datainputstream(                                new fileinputstream(filename))));         // number of lines in text file        numlines = integer.parseint(br.readline().tostring().trim());         // random number , write test text box        int rnd = r.nextint(numlines);        string tmp = integer.tostring(rnd);        testbox.settext(tmp);         // random number - go line - save in string "text"        linenumberreader rdr = new linenumberreader(br);        rdr.setlinenumber(r.nextint(numlines));        textbox.settext(rdr.readline());      } catch (filenotfoundexception e) {         textbox.settext("filenotfound");         e.printstacktrace();     } catch (ioexception e) {         textbox.settext("ioexception");         e.printstacktrace();     } catch (numberformatexception nfe){         textbox.settext("number formated wrong");     } {} 

what doing wrong? have tried closing , reseting br , rdrand can't seem work.

the line number doesn't affect line gets returned, line number reported it.

the whole point of linenumberreader not automatically seek specific line, it's keep track of current line number without having worry it.

in other words, open reader , start reading. when find line of interest, can call getlinenumber() find out line was.

to end, setlinenumber() changes reported line number current line. not move file pointer line in file.

to specific line rnd, simplest solution read rnd lines in loop. last 1 read 1 want. in pseudo-code:

open bufferedreader br limit first line of br set rnd number 1 limit while limit > 0:     set line next line of br     decrement limit use line 

if, or when, turns out inefficient you, can start thinking pre-loading data memory structure of sort.