public class ConnectionRequest extends AsyncTask<Void, Void, String> {


	private HttpURLConnection conn = null;


	@Override
	protected String doInBackground(Void... params) {
		String address = "www.example.co.il/login.php" , attr = "username=moshe&password=123";
		String answer;
		OutputStreamWriter request = null;
		try {
			URL url = new URL(address);
			conn = (HttpURLConnection) *****openConnection();
			conn.setDoOutput(true);
			conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
			conn.setRequestMethod("POST");
			request = new OutputStreamWriter(conn.getOutputStream());
			request.write(attr);
			request.flush();
			request.close();
			BufferedReader in = new BufferedReader(
			new InputStreamReader(conn.getInputStream()));
			String inputLine;
			StringBuilder sb = new StringBuilder();
			while ((inputLine = in.readLine()) != null)
				sb.append(inputLine);
			in.close();
			answer = sb.toString();
		} catch (IOException e) {
		} finally {
			if (conn != null)
				conn.disconnect();
		}
	return answer;
	}

	@Override
	protected void onPostExecute(String params) {
	String answer = params;
	if(answer.equals("true"))
		Toast.makeText(context, "username exists", Toast.LENGTH_SHORT).show();
	else
		Toast.makeText(context, "username not exists", Toast.LENGTH_SHORT).show();
	}
}