How can I send an arraylist through tcp in Java? I need to send an arraylist of integers, from client to server and vice verse.
Thanxx
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4 Answers
import java.io.*;
import java.net.*;
import java.util.*;
import java.util.concurrent.*;
public class SerializeOverSocket {
private static ExecutorService executorService =
Executors.newSingleThreadExecutor();
public static void main(String[] args) throws Exception {
// Start a server to listen for a client
executorService.submit(new Server());
Thread.sleep(100);
// Send an ArrayList from a client
ArrayList<Integer> integers =
new ArrayList<Integer>(Arrays.asList(1,2,3,4,5));
Socket s = new Socket();
s.connect(new InetSocketAddress("localhost", 1234));
ObjectOutputStream out = new ObjectOutputStream(s.getOutputStream());
out.writeObject(integers);
s.close();
}
static class Server implements Runnable {
public void run() {
try {
ServerSocket server = new ServerSocket(1234);
Socket clientSocket = server.accept();
ObjectInputStream in =
new ObjectInputStream(clientSocket.getInputStream());
Object o = in.readObject();
System.out.println("Received this object on the server: " + o);
clientSocket.close();
server.close();
executorService.shutdown();
} catch (IOException e) {
// TODO: Write me
throw new UnsupportedOperationException("Not written");
} catch (ClassNotFoundException e) {
// TODO: Write me
throw new UnsupportedOperationException("Not written");
}
}
}
}
8 Comments
Bozho
oh you have him all the fish :) my answer only gives him the rod and a tells him how to fish)
Ryan Stewart
Ha! Well, I suppose that's true. +1 for that.
Bozho
It will of course save him a lot of time, but it is possible that he just copy-pastes it. @OP try understanding the example before using it.
helloThere
Thanx allot guys. It will indeed save me allot of time, and i do appreciate that.
Ryan Stewart
@helloThere: Like Bozho said, be sure you understand the code. There are some things in there that are only there because it's an example. You wouldn't ever really do them.
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The simplest way would be:
- serialize to
byte[](or directly write to the output stream as shown by Ryan) - open a socket
- write the bytes in the client
- receive the bytes on the server
- deserialize the
byte[](or read from the stream as shown by Ryan)
To handle serialization use ObjectOutputStream and ObjectInputStream. You can also use commons-lang SerializationUtils which give you one-liners to serialize and deserialize.
1 Comment
helloThere
I read your comment above, about the fish i mean :) But the thing is that as many times i have read streams and sockets I cant never seem to understand the completely :(
Look into serialization. Java's ArrayList object already implements the serializable interface, so you just have to learn how to use it.
That example shows how to write an ArrayList to a file, but the same concept applys to sending it over sockets.
2 Comments
helloThere
sorry i cant access the website :(
xunil154
Sorry about that, something strange happened with my paste, here it is agian java2s.com/Tutorial/Java/0140__Collections/…
I know this is a very old question, but perhaps newer versions of the Java lang have make sending objects through TCP easier than in the past. And this is simpler than it seems. Checkout the following example:
Client side of your TCP connection:
//All the imports here
//...
public class Client {
private ObjectInputStream in; //The input stream
private ObjectOutputStream out; //The output stream
private Socket socket; //The socket
public Client(){
//Initialize all the members for your
//Client class here
}
//Using your sendData method create
//an array and send it through your
//output stream object
public void sendData(int[] myIntegerArray) {
try {
//Note the out.writeObject
//this means you'll be passing an object
//to your server
out.writeObject(myIntegerArray);
out.flush();
} catch (IOException ex) {
Logger.getLogger(Client.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
Server side of your TCP connection:
//All the imports here
//...
public class Server {
private ObjectInputStream in; //The input stream
private ObjectOutputStream out; //The output stream
private ServerSocket serverSocket; //The serverSocket
public Server(){
//Initialize all the members for your
//Server class here
}
//Using your getData method create
//the array from the serialized string
//sent by the client
public void getData() {
try {
//Do a cast to transform the object
//into the actual object you need
//which is an Integer array
int[] data = (int[]) in.readObject();
} catch (IOException ex) {
Logger.getLogger(Client.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
