removing delay in sending string through tcp/ip

My project has a light switch which has an IP address and port and accepts strings to control. I am trying to create an application to switch this on and off. My code works, however after the first click, there is a significant delay between the next click and the switch actually switching.

I have a button for on and off. main.java:

package com.android.lswitch;

import android.app.Activity;
import androi开发者_运维技巧d.os.Bundle;
import android.view.View;
import android.widget.Button;

public class lightswitch extends Activity {
/** Called when the activity is first created. */

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    // Handle swon button
    Button swon = (Button) findViewById(R.id.swon);
    swon.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            sw(true);
        }
    });

    // Handle swoff button
    Button swoff = (Button) findViewById(R.id.swoff);
    swoff.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            sw(false);
        }
    });


}

private void sw(boolean swstate) {
    if (swstate == true) {
        Thread swonThread = new Thread(new swon());
        swonThread.start();    
    }

    if (swstate == false) {
    Thread swoffThread = new Thread(new swoff());
    swoffThread.start();    
    }

}
}

and button on java: package com.android.lswitch;

import java.io.BufferedWriter;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.Socket;

public class swon implements Runnable {
public static final String SERVERIP = "10.0.0.25";
public static final int SERVERPORT = 4000;


public void run(){
try {
    InetAddress serverAddr = InetAddress.getByName(SERVERIP);

    Socket socket = new Socket(serverAddr, SERVERPORT);

    String swon = "A55A6B0550000000FFFBDE0030C8";
    String but0 = "A55A6B0500000000FFFBDE002066";

    PrintWriter out = new PrintWriter( new BufferedWriter
            ( new OutputStreamWriter(socket.getOutputStream())),true);

    out.println(swon);
    out.println(but0);
    socket.close();
} catch(Exception e) {
}
    finally {

    }
}
}

button off is virtually the same but with different strings. I'm new to android coding (and java coding) so can't see where the hold up is. Do I need to flush the strings somewhere? or is there a better way of tackling this project?

Cheers

PrintWriter may be buffered, so you should definitely flush() it before issuing any close() operation on the underlying socket.

It is also preferable to call PrintWriter.close() instead of Socket.close(), e.g., in a finally block, such as:

PrintWriter out = new PrintWriter( new BufferedWriter
        ( new OutputStreamWriter(socket.getOutputStream())),true);

try {
  out.println(swon);
  out.println(but0);
  out.flush();
} finally {
  out.close();
}