如何将用户的字符串数据作为字节数组写入套接字

Question

I have a class that receives messages sent by the user and prints them out on the terminal, but now I am trying to write a class that reads data from the user, converts the string data from the user into an array of bytes, and write the byte array to the socket.

I am trying to read data from the user using BufferedReader and write the byte array to the socket using OutputStream, but for some reason, the message that I am writing to the socket isn't delivered to the server.

BufferedReader r = new BufferedReader(new InputStreamReader(System.in));
String newLine = r.readLine();
while (r.ready() && newLine != null) {

    // TODO: read data from the user, blocking until ready. Convert the
    //string data from the user into an array of bytes and write
    //the array of bytes to "socket".

    byte[] message = newLine.getBytes();
    OutputStream outputStream = s.getOutputStream();
    outputStream.write(message);
}

s is the socket with the same server and port number as the one I am sending it to!

There are no errors when I run this, so I genuinely have no idea why this won't send the message to the socket.

Answer 1

String newLine = r.readLine();

Perhaps you misunderstand how java works; your confusion is logical only if you believe that this sets up a sort of alias: That everytime newLine is so much as touched, that it's just a shorthand for r.readLine() .

That is not how java works. You read a line from r exactly once in this code, at the very start, and never again. That line above means: Execute r.readLine() right this very moment, allow that method to put the string it gets someplace in memory, and then have newLine be an alias for that string , not for the general idea of 'pull another string off of the network buffers'.

r.readLine() needs to be somewhere in that loop.

More generally, don't call .ready() , it's not useful. Call readLine() only. Calling that will 'block' until data is available automatically, and will return null when no more data will ever come (because the connection has been closed).