BufferedReader readLine() blocks

Question

When receiving data using readLine(), even though I put a "\n" at the end of the message using the .flush when sending the message, the while loop that reads my message still blocks. Only when closing the socket connection, it leaves the loop.

Here's the client code :

bos = new BufferedOutputStream(socket.
            getOutputStream());
bis = new BufferedInputStream(socket.
            getInputStream());
osw = new OutputStreamWriter(bos, "UTF-8");
osw.write(REG_CMD + "\n");
osw.flush();

isr = new InputStreamReader(bis, "UTF-8");
BufferedReader br = new BufferedReader(isr);

String response = "";
String line;

while((line = br.readLine()) != null){
   response += line;
}

and the server's code:

BufferedInputStream is;
BufferedOutputStream os;

is = new BufferedInputStream(connection.getInputStream());
os = new BufferedOutputStream(connection.getOutputStream());

isr = new InputStreamReader(is);

String query= "";
String line;

while((line = br.readLine()) != null){
   query+= line;
}

String response = executeMyQuery(query);
osw = new OutputStreamWriter(os, "UTF-8");

osw.write(returnCode + "\n");
osw.flush();

My code blocks at the server while loop. Thanks.

Answer 1

The BufferedReader will keep on reading the input until it reaches the end (end of file or stream or source etc). In this case, the 'end' is the closing of the socket. So as long as the Socket connection is open, your loop will run, and the BufferedReader will just wait for more input, looping each time a '\n' is reached.