How to read socket response after writing to ObjectOutputStream?

Question

I am using Socketto send a task from one server to another like so:

private boolean sendRequest(String address, int port) {
    boolean requestComplete = false;
    try {
        Socket socket = new Socket(address, port);
        ObjectOutputStream oos = new ObjectOutputStream(socket.getOutputStream());
        oos.writeObject("task_to_complete");

        ObjectInputStream ois = new ObjectInputStream(socket.getInputStream());
        String msg = (String)ois.readObject();
        if(msg.equals("complete")){
            requestComplete = true;
        }
        ois.close();
        oos.close();
        socket.close();
    } catch (Exception e) {
        e.printStackTrace();
    }
    return requestComplete;
}

The second server receives the task like so:

while (true) {

    // wait for connection
    Socket socket = serverSocket.accept();
    System.out.println("New connection accepted " + socket.getInetAddress() + ":" + socket.getPort());

    // retrieve request from server
    ObjectInputStream ois = new ObjectInputStream(socket.getInputStream());
    String msg = (String) ois.readObject();

    switch (msg) {
    case "task_to_complete":
        // do task 1
        break;
    }

    System.out.println("Task " + msg + " complete.");

    // send a message back to client with the result of the task it
    // requested
    PrintWriter out =
            new PrintWriter(socket.getOutputStream(), true);
        out.print("complete");
    ois.close();
    socket.close();
}

But I get the error

java.io.EOFException at java.io.ObjectInputStream$PeekInputStream.readFully(Unknown Source)

when I attempt to read the message "complete" from the first server: ObjectInputStream ois = new ObjectInputStream(socket.getInputStream());.

What is causing this error?

Raffaele · Accepted Answer · 2016-01-20T15:25:49.483

3

You messed up your protocol because

the server writes the response with PrintWriter.print("completed")
the client reads it with readObject()

I put a working demo on GitHub

edited Jan 20 '16 at 15:25

answered Jan 20 '16 at 15:15

Raffaele

20,627
6
47
86

score 0 · Answer 2 · answered Jan 20 '16 at 14:48

0

try using

BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));

String msg = in.readLine();

if(msg.equals("complete")){
        requestComplete = true;
    }

it worked for me in a similar situation

answered Jan 20 '16 at 14:48

A. Steiner

31
6

This gives me a `NullPointerException` for "msg". – crmepham Jan 20 '16 at 15:04

How to read socket response after writing to ObjectOutputStream?

2 Answers2