what Socket.getInputStream().read() method will do in java?

I have a code like this:

class ConnectionHandler implements Runnable {

private Socket socket;
private InputStream is;
private OutputStream os;
private  Packetizer packetizer;
boolean closed = true;

public ConnectionHandler(Socket 开发者_开发百科socket, ProtocolHandler ph) {
    this.socket = socket;
    try {
        is = socket.getInputStream();
        os = socket.getOutputStream();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
Thread t = new Thread(this);
    t.start();
    //log.debug("ConnectionHandler const done");
}

public void run() {
    try
    {
        //
        // Read a message sent by client application
        //

        closed = false;
        while (!closed)
        {
            if (is.available() > 0) 
            {
                byte c = (byte) (0xff & is.read());
                //log.debug("r " + c);

            } else {
                try {
                    Thread.sleep(100);
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    //e.printStackTrace();
                }
            }
        }

        is.close();
        os.close();
        socket.close();

    } catch (IOException e) {
    }
}

My question is what is the use of this -> byte c = (byte) (0xff & is.read());

Please let me know your thoughts.

Please help me out. Thanks in advance.

It will read a single byte of data from the socket. The 0xff & ... part is unnecessary here (or actually a bad idea), as InputStream.read will only return a value in the range 0-255, unless it's actually reached the end of the data in which case it returns -1.

(Usually 0xff & ... is used to convert a signed byte value into an unsigned int value. Here the input is an int and the result is a byte variable though...)