Java客户端和python服务器连接

Question

i am working on an app in android studio and basiclly i need that whenever i clicked a specific button it will create a connection between the java client and python server.
I first checked when u enter the page\\activity of the specific button if there is a wifi connection in the phone.
It works fine. then i tried to do this and it didnt work (Important to say that the current code make my phone and my app crash and stop)
simple server:

HOST = '192.168.1.21'
PORT = 9000


def main():
    server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    server_socket.bind((HOST, PORT))
    server_socket.listen(10)
    client_socket, client_address = server_socket.accept()
    print 'Connect with ' + client_address[0]
    data = client_socket.recv(1024)
    print "data :"
    print data
    print " end"
    if data == HOST+"/n":
        print 'hi'
    else:
        i = 0
        while i < 15:
            print i
            i += 1
    client_socket.close()
    server_socket.close()
if __name__ == '__main__':
    main()

this is just to check a connection. it might look strange because of the host +/n in the if . i recently chenged it because i am new to java and dont know how the data is sent. but that is not the problem rn.

public void ButtonClicked(View view) {
        EditText editText = findViewById(R.id.edit_text);
        final String ip = editText.getText().toString();
        Toast.makeText(this, ip, Toast.LENGTH_SHORT).show();
        try {
            InetAddress host = InetAddress.getByName(ip);
            final Client client = new Client(host, 9000);
            new Thread(new Runnable() {
                public void run() {
                    try {
                        client.send(ip);
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }).start();
            client.send(ip);
        }
        catch (IOException e) {
            System.out.println("Caught Exception: " + e.toString());
        }

i read that in android studio 3.0 u need to create a thread when u send data. the client class that u see here :

public class Client
{
    private Socket socket = null;
    private BufferedReader reader = null;
    private BufferedWriter writer = null;

    public Client(InetAddress address, int port) throws IOException
    {
        socket = new Socket(address, port);
        reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        writer = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
    }

    public void send(String msg) throws IOException
    {
        writer.write(msg, 0, msg.length());
        writer.flush();
    }

    public String recv() throws IOException
    {
        return reader.readLine();
    }

}

it might be just a simple thing that i dont know of but those are the codes and i cant connect to the server. i figured out that the server works fine because if im connecting from the phone to 192.168.1.21 on the net i receive the connection and it does thw little while. ty for the help - i would like to get the simplest fixes because im new to java.
(sorry if there where grammer\\ spelling mistakes)

Edit- logcat for the crash

Answer 1

At the end of your log it says NetworkOnMainThread. In your code there is a line client.send(ip) below your seperate thread which is executed at the main thread.