Unable to send data from C# to Java (Android) program.

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I am trying to send data from a C#.NET (Windows Application) program to a Java (Android App) program and vice versa, via TCP connection through Wifi. Till now I am success to send data from Java to C#, but unable to do so from C# to Java.

Following is the Java code, I used to create a connection and receive data:

Java

ServerSocket serverSocket = null;
DataInputStream socketInputStream;
while (true) {
        try {
            String localIPAddr = getLocalIPAddress();
            InetSocketAddress ipEndPoint = new InetSocketAddress(
                    InetAddress.getByName(localIPAddr), 8222);
            serverSocket = new ServerSocket();
            serverSocket.bind(ipEndPoint, 4);
            workerSocket = serverSocket.accept();

            socketInputStream = new DataInputStream(
                    workerSocket.getInputStream());
            inputText.setText(socketInputStream.readUTF());
        } catch (Exception ex) {
            throw ex;
        }
    }

Here getLocalIPAddress() method returns the IP Address of the Android Device.

Following is the C# code in Windows Application to connect to the Android's IP Address (192.168.1.6) and send data to it:

C#

Socket clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
void button1_Click(object sender, EventArgs e)
        {
            try
            {
                if (!clientSocket.Connected)
                    clientSocket.Connect(IPAddress.Parse("192.168.1.6"), 8222);
                clientSocket.Send(Encoding.UTF8.GetBytes(txtInput.Text));
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }

Well, client (C#) is failing to connect to the server (Java) That means data is not leaving from client. But it will, if it get connected.

Please tell me what am I missing and where am I mistaken. :)

Posted 19-Feb-12 19:54pm

iKrshnan

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[no name] 20-Feb-12 7:55am

I got the solution myself and now it is receiving data from C#. But it is still freezing at last line: inputText.setText(socketInputStream.readUTF()) and not moving ahead. So now just want to know how to get String from the byte that sent by C# code.

2 solutions

Solution 1

doesn't the Java code run into a heap space exception as you are constantly creating connections and streams??

Posted 19-Feb-12 20:10pm

TorstenH.

Comments

[no name] 20-Feb-12 2:28am

Yes, there is an exception at workerSocket = serverSocket.accept(); line in Java code and the app is freezing in Android device.

TorstenH. 20-Feb-12 5:00am

so YOU ARE running into Heap Space Exceptions? There you go. Don't use an infinite, never ending while-loop to create connections.

I would infact make it a Singleton and use a method getInstance() to retrieve the same object for the connection each time - otherwise you'll end up with a big stack of unclosed connections waiting for the timeout...
Link for Singeltons explanation: http://java.sun.com/developer/technicalArticles/Programming/singletons/

[no name] 20-Feb-12 8:05am

I got the solution myself and now it is receiving data from C#. But it is still freezing at last line: inputText.setText(socketInputStream.readUTF()) and not moving ahead. So now just want to know how to get String from the byte that sent by C# code.

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iKrshnan · Accepted Answer · 2012-02-21T19:06:00

Well, I have solved this myself.

Check out the solved Java code below:

Java

ServerSocket serverSocket = null;
Socket workerSocket;
DataInputStream socketInputStream;
try {
    if (serverSocket == null) {
        // No need to get local IP address and to bind InetSocketAddress.
        // Following single line make it very simple.
        serverSocket = new ServerSocket(8222, 4);
        workerSocket = serverSocket.accept();
    }
    // When data are accepted socketInputStream will be invoked.
    socketInputStream = new DataInputStream(
                workerSocket.getInputStream());

    /* Since data are accepted as byte, all of them will be collected in the
    following byte array which initialised with accepted data length. */
    byte[] rvdMsgByte = new byte[socketInputStream.available()];

    // Collecting data into byte array
    for (int i = 0; i < rvdMsgByte.length; i++)
        rvdMsgByte[i] = socketInputStream.readByte();

    // Converting collected data in byte array into String.
    String rvdMsgTxt = new String(rvdMsgByte);

    // Setting String to the text view.
    receivedMsg.setText(rvdMsgTxt);
} catch (Exception ex) {
    throw ex;
}

Note that a separate thread is to be used to run this code in background.

Unable to send data from C# to Java (Android) program.

2 solutions

Solution 1

Solution 2

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Unable to send data from C# to Java (Android) program.

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