Why lots of spaces append when I received some data from sockets?

Question

Hi I am writing a simple java program to read data from sockets, but caught in a problem, where after each input I get lots of spaces present.

AIM: Write a simple server socket which can read CORRECT data from client socket.

So far: I have been able to write the code to read from socket, even able to read the data, but the thing is I get lots of spaces at the end.

So I had to use trim(), in the end to manage spaces, but I still don't know if this is right or wrong.

Would appreciate the inputs on this.

NOTE: I am using windows7 telnet service to connect to socket.

readSocket() {
    System.out.println(client_socket);
    try {
        System.out.println("reading socket");
        /*BufferedReader brIn = new BufferedReader(new InputStreamReader(client_socket.getInputStream()));
        String inputLine = null;
        while ((inputLine = brIn.readLine()) != null) {
            System.out.println(inputLine);
        }*/
        InputStream is = client_socket.getInputStream();
        byte[] byteArr = new byte[1024];
        int inputsize = -1;
        int currentPos = 0;
        StringBuffer sb = new StringBuffer(11111);
        /*while((inputsize = is.read(byteArr)) != -1) {
            String processed = new String(byteArr);
            sb.append(processed);
        }*/
        int BUFFER_SIZE = 1024;
        int read;
        byte[] buffer = new byte[BUFFER_SIZE];
        String processed = "";
        while ((read = is.read(byteArr, 0, BUFFER_SIZE)) != -1) {
            String current = new String(byteArr);
            //os.write(buffer, 0, read);
            System.out.println("current Process   "+current);

            //processed +=current;
            sb.append(current.toString().trim());
        }
        System.out.println("Socket input is : "+sb.toString());
        System.out.println("Sending response to client  "+processed.toString());
        //client_socket.getOutputStream().write(sb.toString().getBytes());
        //client_socket.getOutputStream().close();

        FileOutputStream fos = new FileOutputStream(new File("C:\\Users\\himanshu2100\\eee.txt"));
        fos.write(processed.getBytes());
        fos.close();
        is.close();
        client_socket.close();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

Well using the suggestion of both Roger Lindsjö and mprivat, I redesigned the part where I read from stream.

readSocket() {
    System.out.println(client_socket);
    try {
        System.out.println("reading socket");
        InputStream is = client_socket.getInputStream();
        byte[] byteArr = new byte[1024];

        int read;
        int BUFFER_SIZE = 1024;

        ByteArrayOutputStream baos = new ByteArrayOutputStream();

        while ((read = is.read(byteArr, 0, BUFFER_SIZE)) != -1) {
            baos.write(byteArr, 0, read);   //This is an optimized design, instead of having so many strings
        }
        System.out.println("Output is :"+new String(baos.toByteArray()));
        baos.close();
        is.close();
        client_socket.close();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

I hope this one's a better solution so posting it. Suggestions welcome.

Answer 1

When you read into an array the whole array might not be filled. The read variable will contain the number of actual bytes read.

    while ((read = is.read(byteArr, 0, BUFFER_SIZE)) != -1) {
        String current = new String(byteArr, 0, read);
        System.out.println("current Process   "+current);
        sb.append(current);
    }

If you use an encoding which is multi byte the above might not work as each part of the character could be in separate reads, this creating invalid sequences.