java - How to use inputstream mark and reset functions? -

i'm trying read first 8192 bytes file , run bytes through method returns boolean.

that boolean tells me if file of particular type.

if method returns true on bytes file type want remaining bytes , run them through different method. if false, run remaining bytes through different method.

i'm trying use mark, having no success.

private final void handlefile(inputstream inputstream) {     bufferedinputstream bis = new bufferedinputstream(inputstream);    bis.mark(8192);    byte[] startingbytes = inputstreamtobytearray(bis);     if(startingbytes.length == 0) { return; }     byte[] finalbytes;    if(isfiletype(startingbytes)) {       bis.reset();       finalbytes = inputstreamtobytearray(bis);       methodforfinalbytes(finalbytes);    } else {       // other stuff;    } }  private byte[] inputstreamtobytearray(inputstream inputstream) {    bytearrayoutputstream baos = new bytearrayoutputstream();    byte[] buffer = new byte[8192];     try {       while(inputstream.read(buffer) != -1) {           baos.write(buffer);       }    } catch(ioexception ioe) {       ioe.printstacktrace();    }  return baos.tobytearray(); } 

problem picking left off while keeping byte array in chunks (for processing against large files). also, i'm getting 8192 bytes returned , not remaining.

any suggestions?

first, looks inputstreamtobytearray()is reading entire stream until end of file, not first 8192 bytes. want read first 8192 bytes separately first.

second, want re-read bytes again? if not, i'm not sure if need mark/reset. (especially since still have byte array )

the code below reads first 8192 bytes first, decides do:

byte[] header = new byte[8192]; //reads entire array or until eof whichever first bis.read(header);  if(isfiletype(header)) {   byte[] finalbytes = inputstreamtobytearray(bis);   methodforfinalbytes(finalbytes); } else {   // other stuff; }