multithreading - Java socket is stuck on readUTF() -

i'm trying transfer files on socket in java, current approach server is:

1. create new thread
2. thread sends file name using dos.writeutf()
3. thread sends file size using dos.writelong()
4. thread sends file using dos.write()

where each thread represents client , dos instance of dataoutputstream.

now, on client i'm doing same thing reading instead of writing:

1. read file name using dis.readutf()
2. read file size using dis.readlong()
3. read file using dis.read()

where dis instance of datainputstream.
problem is: when sending 1 file, goes right, when try send 3 files, 1 after another, looks server writing correctly stream expected client (after first file, means starts happening second file) stuck on dis.readutf() , can't move on.

i've tried fixing days can't work.
here's source code:

server:

main.java

 public class main {     public static void main(string[] args) {         boolean booldebug = true;//todo remove this!!         serversocket serversock = null;         list<socket> clientsocks;         list<clientthread> clientthreads;         try {             serversock = new serversocket(9090);         } catch(exception e){             e.printstacktrace();         }         clientsocks = new arraylist<>();         clientthreads = new arraylist<>();         serversocket finalserversock = serversock;          system.out.println();         system.out.println("listening incoming connections\n");         new thread(){             @override             public void run() {                 super.run();                 while (true) {                     try {                         socket newsock = finalserversock.accept();                         clientsocks.add(newsock); //fixme remove sockets when closed                         thread thread = new clientthread(newsock, usr, psw);                         thread.start();                         clientthreads.add((clientthread)thread);                     } catch (exception e) {                         e.printstacktrace();                     }                 }             }         }.start();     } } 

clientthread.java

public class clientthread extends thread {     private socket socket;     private datainputstream instream;     private dataoutputstream outstream;     private string dbuser;     private string dbpassword;      public clientthread(socket socket, string dbuser, string dbpass) {         this.socket = socket;         this.dbuser = dbuser;         this.dbpassword = dbpass;     }      @override     public void run() {         try {             instream = new datainputstream(socket.getinputstream());             outstream = new dataoutputstream(socket.getoutputstream());             sendfile("a.txt");             sendfile("b.txt");             sendfile("c.txt");         } catch (exception e) {             e.printstacktrace();         }     }       void sendfile(string file){         try {             file f = new file(file);             outstream.writeutf(file);             outstream.writelong(f.length());             fileinputstream fis = new fileinputstream(f);             byte[] buffer = new byte[4096];              while (fis.read(buffer) > 0) {                 outstream.write(buffer);             }             fis.close();         }catch(exception e){             e.printstacktrace();         }      }     int getsize(byte[] buffer,long remaining){         try {             return math.tointexact(math.min(((long) buffer.length), remaining));         }catch(arithmeticexception e){             return 4096;         }     }  } 

client: main.java

class main {      static int getsize(byte[] buffer, long remaining) {         try {             return math.tointexact(math.min(((long) buffer.length), remaining));         } catch (arithmeticexception e) {             return 4096;         }     }      static void savefile(socket clientsock,datainputstream dis) throws ioexception {          string filename = dis.readutf();         file f = new file(filename);         fileoutputstream fos = new fileoutputstream(f);         byte[] buffer = new byte[4096];          long filesize = dis.readlong();         int read = 0;         int totalread = 0;         long remaining = filesize;          while ((read = dis.read(buffer, 0, getsize(buffer, remaining))) > 0) {             totalread += read;             remaining -= read;             system.out.println("read " + totalread + " bytes.");             fos.write(buffer, 0, read);         }         fos.close();     }      public static void main(string[] args) throws exception {         socket sock = new socket("192.168.2.17", 9090);         datainputstream dis = new datainputstream(sock.getinputstream());         savefile(sock,dis);         savefile(sock,dis);         savefile(sock,dis);      } } 

many in advance, looking forward fix :(

fixed changing

while (fis.read(buffer) > 0) {     outstream.write(buffer); } 

to

int count; while ((count = fis.read(buffer)) > 0) {     outstream.write(buffer, 0, count); } 

inside clientthread.java on server side