I am trying to create a Java program to send a message from client to Server and receive a response back using socket programming but it's coming up with this error:
Exception in thread "main" java.net.BindException: Address already in use: JVM_Bind at java.net.DualStackPlainSocketImpl.bind0(Native Method) at java.net.DualStackPlainSocketImpl.socketBind(DualStackPlainSocketImpl.java:106) at java.net.AbstractPlainSocketImpl.bind(AbstractPlainSocketImpl.java:387) at java.net.PlainSocketImpl.bind(PlainSocketImpl.java:190) at java.net.ServerSocket.bind(ServerSocket.java:375) at java.net.ServerSocket.(ServerSocket.java:237) at java.net.ServerSocket.(ServerSocket.java:128) at Bob.main(Bob.java:9)
client side:
public static void main(String[] args) throws IOException {
InetAddress addr = InetAddress.getByName("127.0.0.1") ; //set the address of the server to be connected to. Any IP address can be set here as a string
//If the name is saved in your "etc/hosts" file, then the name can be used instead of the ip address
//Alternative method: InetAddress.getByAddress -see "stackoverflow" explanation if interested
System.out.println("addr = " + addr);
Socket socket = new Socket(addr, 8080); //attempt to connect to the server by creating a socket using the IP address and Port number of the server
try {
System.out.println("socket = " + socket);
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream())); //create an input variable for the socket- accepts input from the socket
PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())),true); // create an output variable for the socket- writes output to the socket
//this loop simply writes to the socket 10 times waits for a reply from the socket and then prints the reply received
for(int i = 0; i < 10; i ++) {
out.println("I am it: " + i); //write to socket
String str = in.readLine(); //read from socket
System.out.println(str); //print to console line read from socket
}
out.println("END"); //send string that indicates end of transmission
}catch( SocketException e ) {
System.out.println("Server closed connection");
}finally{
System.out.println("closing...");
socket.close(); //close the connection
}
}
server side:
public static final int PORT = 8080;
public static void main(String[] args) throws IOException {
ServerSocket s = new ServerSocket(PORT); //create server socket object
System.out.println("Started: " + s);
try {
Socket socket = s.accept(); //accept a socket connection using the Server Socket created previously
try {
System.out.println("Connection accepted: "+ socket);
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream())); //create an input variable for the socket- accepts input from the socket
PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())),true); // create an output variable for the socket- writes output to the socket
//this loop accepts input from the socket, prints out what it receives anc echoes it back into the socket until it recives the word "END" indicating the end of transmission
while (true) {
String str = in.readLine(); //read line from socket
if (str.equals("END")) break;
System.out.println("Echoing: " + str); //print line to console
out.println("You said: " + str); //echo line read back into socket
}
}catch ( SocketException e ) {
System.out.println("Client closed connection");
}finally{ //close the present connection
System.out.println("closing...");
socket.close();
}
}catch( SocketException e ){
System.out.println("Server socket closed unexpectedly");
}finally{ //close the server socket. i.e. stop listening for connections
s.close(); //without this line, the server would continue waiting for another connection
}
}
