Please give me flowchart for this code...

Question

Writing a Java applet to communicate with a serial device attached to the Device
Server is very straightforward. However, familiarity with Java programming and a
Java compiler are required.
As with any network application, open a communication channel to the remote
device. In our example, a socket is opened and and two data streams are created to
perform the actual sending and receiving of data.
The following example uses a new Java Class called tcpip. Copy the following code
into a file called tcpip.java.
import java.*;
import java.lang.*;
import java.net.*;
import java.util.*;
import java.io.*;
* This class opens a TCP connection, and allows reading and writing of byte
arrays.
public class tcpip
protected Socket s = null;
public DataInputStream dis = null;
protected DataOutputStream dos = null;
public tcpip(InetAddress ipa, int port)
Socket s1 = null;
try { // Open the socket
s1 = new Socket(ipa.getHostAddress(), port);
catch (IOException e) {
System.out.println("Error opening socket");
return;
s = s1;
try { // Create an input stream
dis = new DataInputStream(new
BufferedInputStream(s.getInputStream()));
catch(Exception ex) {
System.out.println("Error creating input stream");
try { // Create an output stream
dos = new DataOutputStream(new
BufferedOutputStream(s.getOutputStream()));
catch(Exception ex) {
System.out.println("Error creating output stream");
public synchronized void disconnect()
if (s != null) {
try {
s.close();
catch (IOException e){}
public synchronized void send(byte[] temp)
try {
dos.write(temp, 0, temp.length);
dos.flush();
catch(Exception ex) {
System.out.println("Error sending data : " + ex.toString());
public synchronized void send(byte[] temp, int len)
try {
dos.write(temp, 0, len);
dos.flush();
catch(Exception ex) {
System.out.println("Error sending data : " + ex.toString());
public synchronized void send(String given)
// WARNING: this routine may not properly convert Strings to bytes
int length = given.length();
byte[] retvalue = new byte[length];
char[] c = new char[length];
given.getChars(0, length, c, 0);
for (int i = 0; i < length; i++) {
retvalue[i] = (byte)c;
send(retvalue);
public synchronized byte[] receive()
byte[] retval = new byte[0];
try {
while(dis.available() == 0); /* Wait for data */
catch (IOException e){}
try {
retval = new byte[dis.available()];
catch (IOException e){}
try {
dis.read(retval);
catch (IOException e){}
return(retval);
public int available()
int avail;
avail = 0;
try {
avail = dis.available();
catch (IOException e) {}
return(avail);
Next, create the Text_io class as the application. Copy the following code
into a file called �Text_io.java�.
import java.awt.*;
import java.awt.event.*;
import java.lang.*;
public class Text_io extends Panel implements Runnable,
TextListener {
private tcpip gtp;
String oldmessage = new String("");
TextArea input_box = new TextArea("", 10, 60, 3);
TextArea output_box = new TextArea("", 10, 60, 3);
Thread timer;
public Text_io(tcpip tp) {
gtp = tp;
setLayout(new GridBagLayout());
GridBagConstraints c = new GridBagConstraints();
c.insets = new Insets(5,5,5,5);
setBackground(java.awt.Color.lightGray);
setSize(561,380);
c.gridx = 0; c.gridy = 2; c.gridwidth = 1; c.gridheight =
1;
c.weightx = 0.0; c.weighty = 0.0; c.anchor =
GridBagConstraints.WEST;
c.fill = GridBagConstraints.NONE;
add((new Label("To Device Server: (Type Here--->)")), c);
//input_box
input_box.addTextListener(this);
c.gridx = 1; c.gridy = 2; c.gridwidth = 3; c.gridheight =
1;
c.weightx = 0.5; c.weighty = 0.0; c.anchor =
GridBagConstraints.CENTER;
c.fill = GridBagConstraints.BOTH;
add(input_box,c);
c.gridx = 0; c.gridy = 4; c.gridwidth = 1; c.gridheight =
1;
c.weightx = 0.0; c.weighty = 0.0; c.anchor =
GridBagConstraints.WEST;
c.fill = GridBagConstraints.NONE;
add((new Label("From Device Server:")), c);
c.gridx = 1; c.gridy = 4; c.gridwidth = 3; c.gridheight =
1;
c.weightx = 0.5; c.weighty = 0.0; c.anchor =
GridBagConstraints.CENTER;
c.fill = GridBagConstraints.BOTH;
add(output_box,c);
output_box.setEditable(false);
timer = new Thread(this);
timer.start();
public void run() {
int i;
byte[] in;
Thread me = Thread.currentThread();
while (timer == me) {
try {
Thread.currentThread().sleep(200);
catch (InterruptedException e) { }
if ( (gtp != null) && ((i = gtp.available()) > 0) ) {
in = gtp.receive();
/* remove non-printing bytes */
for (i = 0; i < in.length; i++) {
if (in[i] < 0x20)
in[i] = 0x20;
output_box.append((new String(in)));
public void textValueChanged(TextEvent e) {
int len, i;
String str = new String("");
String message = input_box.getText();
len = message.length() - oldmessage.length();
if (len < 0) {
for (i = 0; i < -len; i++)
str += "\b";
//System.out.println("Backspace");
else if (len > 0) {
str = message.substring(oldmessage.length());
//System.out.println("len = "+str.length()+" str =
"+str);
oldmessage = message;
if ( (len != 0) && (gtp != null) )
gtp.send(str);
Next, create the actual applet that uses the tcpip and Text_io classes. Copy
the following code into a file called �Test.java�.
import java.awt.*;
import java.awt.event.*;
import java.applet.Applet;
import java.net.*;
import java.io.*;
import java.lang.*;
import java.text.*;
import java.util.*;
public class Test extends Applet {
static private boolean isapplet = true;
static private InetAddress arg_ip = null;
static private int arg_port = 0;
public tcpip gtp = null;;
InetAddress reader_ip = null;
int port = 10001;
public void init()
gtp = null;
reader_ip = null;
port = 10001;
public void start()
String st = new String("TCP/IP connection status: ");
setFont(new Font("Dialog",Font.BOLD,16));
setLayout(new GridBagLayout());
GridBagConstraints c = new GridBagConstraints();
c.gridx = 0; c.gridy = 0; c.gridwidth = 1; c.gridheight
= 1;
c.anchor = GridBagConstraints.CENTER;
c.fill = GridBagConstraints.BOTH;
c.insets = new Insets(5,5,5,5);
setBackground(Color.yellow);
setSize(600,500);
/* Either get the IP address from the HTTP server if
we're an applet, or from the commandline (if passed).
if (isapplet) {
try{
reader_ip = InetAddress.getByName(getCodeBase().getHost());
catch (UnknownHostException e){}
else {
reader_ip = arg_ip;
if (arg_port != 0) {
port = arg_port;
/* Open a socket to the Device Server's serial port
if (reader_ip != null) {
if (gtp == null) {
gtp = new tcpip(reader_ip, port);
if (gtp.s == null) {
st += "Connection FAILED! ";
gtp = null;
if (gtp == null) {
st += "Not Connected";
add((new Label(st)), c);
return;
st += "Connected";
add((new Label(st)), c);
/* You may now perform IO with the Device Server via
* gtp.send(byte[] data_out);
* byte[] data_in = gtp.receive();
* functions.
* In our example we'll use two TextBoxes which have
* been extended to handle IO to the Device Server.
*Data typed in the upper text box will be sent to
* the Device Server, and data received will be
*displayed in the lower text box.
/* Start of custom application code */
/* ADD YOUR CODE HERE */
c.gridx = 0; c.gridy = 2; c.gridwidth = 3; c.gridheight =
1;
c.anchor = GridBagConstraints.WEST;
add((new Text_io(gtp)), c);
/* End of custom application code */
public void destroy()
if (gtp != null)
gtp.disconnect();
gtp = null;
public void stop() {
public static void main(String[] args) {
Frame frame = new Frame("TCP/IP Test");
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
if (args.length > 0) {
try{
arg_ip = InetAddress.getByName(args[0]);
catch (UnknownHostException e){}
if (args.length > 1) {
try {
arg_port = Integer.valueOf(args[1]).intValue();
catch (NumberFormatException e) {}
Test ap = new Test();
frame.add(ap);
ap.init();
isapplet = false;
ap.start();
frame.pack();
frame.show();

Answer 1

Let's see a decent try by you towards a solution first. I've found that usually the more thought and effort posters put into creating and solving their questions, the better their chances are of a volunteer here taking the time and effort to consider it and give a helpful answer. In other words, show that you are putting effort into doing your own homework first.
Also, when posting your code, please use code tags so that your code will retain its formatting and be readable. To do this, you will need to paste already formatted code into the forum, highlight this code, and then press the "code" button at the top of the forum Message editor prior to posting the message. You may want to click on the Preview tab to make sure that your code is formatted correctly. Another way is to place the tag &#91;code] at the top of your block of code and the tag &#91;/code] at the bottom, like so:
&#91;code]
  // your code block goes here.
  // note the differences between the tag at the top vs the bottom.
&#91;/code]or
{&#99;ode}
  // your code block goes here.
  // note here that the tags are the same.
{&#99;ode}good luck