Question
I am having a problem with a client-server application. The program runs correctly through until the second time the client must input data. Upon debugging the code it appears that the client always crashes on the line linesIn = din.readInt(); on the second iteration through the loop.
as suggested I added a try catch block around the integer parsing and it seems to have helped move the program further along but now when run the program will only give the correct output to the user once and after that will display the list of options available twice and then not accept any further input
The following output is displayed in the client:
https://stackoverflow.com/questions/18360572
italiano
english
français
española
中国
日本の
العربية
Deutsch
한국어
Português
Russian The address and hostname are: BOO-PC/192.168.0.8
The Hostname: BOO-PC
The Address only: 192.168.0.8
Server: Welcome please make your selection from the options below
Server: 1: make a booking
Server: 2: cancel a booking
Server: 3: view available films
Server: 4: logout
Client:
3
Server: Title :Film1
Server: Time : 10.3
Server: Date : 10 7 2013
Server: Price : 5.0
Server: Referance Number : 55
Server:
Client:
Server:
and this error on the server
Exception in thread "serverThread" java.lang.NumberFormatException: For input string: ""
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
at java.lang.Integer.parseInt(Integer.java:481)
at java.lang.Integer.parseInt(Integer.java:527)
at systemssoftwarebookingsystem.serverThread.run(serverThread.java:45)
server thread code:
package systemssoftwarebookingsystem;
import java.net.*;
import java.io.*;
import java.util.Scanner;
public class serverThread extends Thread
{
private Socket socket = null;
private PrintWriter write = null;
private BufferedReader read = null;
public serverThread(Socket socket)
{
super("serverThread");
this.socket = socket;
}
public void run()
{
Scanner in;
in = new Scanner(System.in);
char[] input;
int inputReferance = 0;
int inputSeatAmount = 0;
boolean filmFound = false;
boolean exit = false;
try
{
read = new BufferedReader(new InputStreamReader(socket.getInputStream()));
write = new PrintWriter(new DataOutputStream(socket.getOutputStream()));
DataOutputStream out = new DataOutputStream(socket.getOutputStream());
int choice = 0;
while (exit == false)
{
choice = 0;
out.writeInt(5);
write.println("Welcome please make your selection from the options below \n 1: make a booking \n 2: cancel a booking \n 3: view available films \n 4: logout");
write.flush();
input = new char[1];
read.read(input);
choice = Integer.parseInt(new String(input));
switch (choice)
{
case 1:
{
Film tempFilm = null;
out.writeInt(1);
write.println("Please enter the referance number of the film you wish to watch");
write.flush();
read.read(input);
inputReferance = Integer.parseInt(new String(input));
for (Film s : server.filmList)
{
if (s.referanceNumber == inputReferance)
{
filmFound = true;
tempFilm = s;
}
}
if (filmFound == false)
{
out.writeInt(1);
write.println("Sorry. That referance number was not recognised. Please try again");
write.flush();
break;
}
if (filmFound == true)
{
out.writeInt(1);
write.println("Please enter the numbe rof seats you wish to book");
write.flush();
inputSeatAmount = read.read(input);
inputSeatAmount = Integer.parseInt(new String(input));
if (tempFilm.seatsAvailable < inputSeatAmount)
{
out.writeInt(2);
write.println("Sorry. There are not enough seats available for that film \n Only " + tempFilm.seatsAvailable + "seats are available");
write.flush();
break;
}
server.bookings.add(new Booking(inputReferance, server.bookingNumber, inputSeatAmount));
server.bookingNumber++;
out.writeInt(1);
write.println("booking placed successfully");
write.flush();
break;
}
}
case 2:
{
out.writeInt(1);
write.println("Please enter the booking number of the booking you wish to cancel");
write.flush();
inputReferance = read.read(input);
inputReferance = Integer.parseInt(new String(input));
for (Booking s : server.bookings)
{
if (s.bookingNumber == inputReferance)
{
filmFound = true;
break;
}
}
if (filmFound == false)
{
out.writeInt(1);
write.println("Sorry. That booking number was not recognised. Please try again");
write.flush();
break;
}
server.bookings.remove(inputReferance);
out.writeInt(1);
write.println("booking cancelled");
write.flush();
break;
}
case 3:
{
for (Film s : server.filmList)
{
out.writeInt(6);
write.println("Title :" + s.name + "\n Time : " + s.showingTime + "\n Date : " + s.day + " " + s.month + " " + s.year + "\n Price : " + s.price + "\n Referance Number : " + s.referanceNumber + "\n");
write.flush();
}
out.writeInt(1);
write.println("end of list");
write.flush();
break;
}
case 4:
{
exit = true;
out.writeInt(1);
write.println("Bye.");
write.flush();
break;
}
}
}
socket.close();
} catch (IOException e)
{
e.printStackTrace();
}
}
}
client code:
package syssoftclient;
import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;
public class Syssoftclient
{
public static void main(String[] args) throws IOException
{
try
{
InetAddress internetAddress = InetAddress.getLocalHost();
System.out.println("The address and hostname are: " + internetAddress);
System.out.println("The Hostname: " + internetAddress.getHostName());
System.out.println("The Address only: " + internetAddress.getHostAddress());
} catch (UnknownHostException e)
{
System.err.println("Connection problem " + e);
}
Socket SocketC = null;
PrintWriter out = null;
BufferedReader in = null;
boolean exit = false;
try
{
SocketC = new Socket(InetAddress.getLocalHost().getHostName(), 8888);
out = new PrintWriter(SocketC.getOutputStream(), true);
in = new BufferedReader(new InputStreamReader(SocketC.getInputStream()));
} catch (UnknownHostException e)
{
System.err.println("Host not recognised");
System.exit(1);
} catch (IOException e)
{
System.err.println("Couldn't get I/O for the connection");
System.exit(1);
}
String fromServer = null;
String fromUser = null;
BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));
DataInputStream din;
din = new DataInputStream(SocketC.getInputStream());
int lineCount = 0;
int linesIn = 0;
while (exit == false)
{
lineCount = 0;
linesIn = din.readInt();
while (lineCount < linesIn)
{
fromServer = in.readLine();
System.out.println("Server: " + fromServer);
lineCount++;
}
if ("Bye.".equals(fromServer))
{
System.out.println("Quitting");
exit = true;
break;
}
System.out.println("Client: ");
fromUser = stdIn.readLine(); //reads userinput
if (fromUser != null)
{
out.println(fromUser); //sends user input to the server
out.flush();
}
if ("exit".equals(fromUser))
{
exit = true;
}
}
out.close();
in.close();
stdIn.close();
SocketC.close(); //close everything before ending program
}
}
Solution
Based on your updated question, I think there error is here:
choice = Integer.parseInt(new String(input));
I'm not sure as I don't know exactly what line number 45 is.
You're trying to parse a new line character as an integer. This is throwing an exception, causing the server to exit its while loop, and the program to close.
So, wrap your parsing routines in try/catch blocks and handle them. The error should go away then.
