Develop Reference

How do I send data from an android wearable device to a phone in the form of a a simple text file containing data?

I have a wearable app. The app after it finishes has data like time/date, UUID, Geo location, parameters selected displayed in front of me like a Data Report or Log in several TextViews underneath each other. Like a list. I want this data to be transferred from my wearable device to my android phone.
Now I have to ask does the WearOS app the pairs the phone with the watch enables such a thing? Like can the data be sent through it? OR what exactly can I do? I read about Sync data items with the Data Layer API in the documentation, but I'm not sure if the code snippets provided would help achieve what I want.
public class MainActivity extends Activity {
private static final String COUNT_KEY = "com.example.key.count";
private DataClient dataClient;
private int count = 0;
...
// Create a data map and put data in it
private void increaseCounter() {
PutDataMapRequest putDataMapReq = PutDataMapRequest.create("/count");
putDataMapReq.getDataMap().putInt(COUNT_KEY, count++);
PutDataRequest putDataReq = putDataMapReq.asPutDataRequest();
Task<DataItem> putDataTask = dataClient.putDataItem(putDataReq);
}
...
}
The data I display in the textviews are called through methods that I call things like: getLocation, getUUID, getDateTime, getSelections, etc... when I click a button I call them in the setOnClickListener. I want this data in the TextViews to be placed in a file or something like that and send them over to the mobile phone from the watch when they're generated.
private void getDateTime()
{
SimpleDateFormat sdf_date = new SimpleDateFormat("dd/MM/yyyy");
SimpleDateFormat sdf_time = new SimpleDateFormat("HH:mm:ss z");
String currentDate= sdf_date.format(new Date());
String currentTime= sdf_time.format(new Date());
textView_date_time.setText("Date: "+currentDate+"\n"+"Time: "+currentTime);
}
#SuppressLint("SetTextI18n")
private void getUUID()
{
// Retrieving the value using its keys the file name
// must be same in both saving and retrieving the data
#SuppressLint("WrongConstant") SharedPreferences sh = getSharedPreferences("UUID_File", MODE_APPEND);
// The value will be default as empty string because for
// the very first time when the app is opened, there is nothing to show
String theUUID = sh.getString(PREF_UNIQUE_ID, uniqueID);
// We can then use the data
textView_UUID.setText("UUID: "+theUUID);
}
#SuppressLint("SetTextI18n")
private void getSelections()
{
textView_data_selected.setText("Tool No.: "+c.getToolNo()+
"\nTool Size: " +c.getToolSizeStr()+
"\nFrom Mode: " +c.getCurrentModeStr()+
"\nGoto Mode: " +c.getModeStr()+
"\nMethod: " +c.getMethodStr()+
"\nBit Duration: " +c.getBitDuration()+
"\nUpper bound" +c.getUpStageValue()+
"\nLower bound: "+c.getDownStageValue());
}
The above are examples of the methods I use to get the data. then I call them here:
gps_btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (Build.VERSION.SDK_INT >= 26) {
getLocation();
getDateTime();
getUUID();
getSelections();
}
else
{
//ActivityCompat.requestPermissions(get_location.this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 1);
Toast.makeText(get_location.this,"Build SDK too low",Toast.LENGTH_SHORT);
}
}
});
Now how do I take all this and send it over from my device to the the phone?
Note: The data report I want to send as a file, I want it done subtly like something done in the background. I don't know what else to do or where to look.

You have two options if you want to use the Data Layer, one is to use the MessageClient API to bundle your data up in a message and send it directly to the handheld. The easiest here would be to create an arbitrary JSONObject and serialize your data as a JSON string you can stuff into a message. For example:
try {
final JSONObject object = new JSONObject();
object.put("heart_rate", (int) event.values[0]);
object.put("timestamp", Instant.now().toString());
new MessageSender("/MessageChannel", object.toString(), getApplicationContext()).start();
} catch (JSONException e) {
Log.e(TAG, "Failed to create JSON object");
}
In my case, I do this in my onSensorChanged implementation, but you can insert this wherever you are updating your text.
MessageSender is just a threaded wrapper around the MessageClient:
import java.util.List;
class MessageSender extends Thread {
private static final String TAG = "MessageSender";
String path;
String message;
Context context;
MessageSender(String path, String message, Context context) {
this.path = path;
this.message = message;
this.context = context;
}
public void run() {
try {
Task<List<Node>> nodeListTask = Wearable.getNodeClient(context.getApplicationContext()).getConnectedNodes();
List<Node> nodes = Tasks.await(nodeListTask);
byte[] payload = message.getBytes();
for (Node node : nodes) {
String nodeId = node.getId();
Task<Integer> sendMessageTask = Wearable.getMessageClient(context).sendMessage(nodeId, this.path, payload);
try {
Tasks.await(sendMessageTask);
} catch (Exception exception) {
// TODO: Implement exception handling
Log.e(TAG, "Exception thrown");
}
}
} catch (Exception exception) {
Log.e(TAG, exception.getMessage());
}
}
}
The other option is to create a nested hierarchy of data items in the Data Layer and implement DataClient.OnDataChangedListener on both sides, such that changes that are written in on one side are automatically synchronized with the other. You can find a good walkthrough on how to do that here.
For your specific case, just packing it in a JSON object would probably be the simplest. The writing out to your preferred file format you can then implement on the handheld side without needing to involve the wear side.

Android studio connectivity with postgresql

I'm new to android and not much aware about it. I though have been through tutorial but still didn't get any solution. How to connect Android Studio with postgressql? Step by step!
I wrote this code in my MainActitvity.java. Is this correct? Or should I write it else where?
static final String JDBC_DRIVER = "org.postgresql.Driver";
static final String DB_URL = "jdbc:postgresql://localhost:5432/user1";
// Database credentials
static final String USER = "root";
static final String PASS = "root";
public static void main(String[] args)
{
Connection conn = null;
Statement st = null;
try{
//STEP 2: Register JDBC driver
Class.forName("org.postgresql.Driver");
//STEP 3: Open a connection
System.out.println("Connecting to database...");
conn = DriverManager.getConnection("jdbc:postgresql://localhost:5432/","root","root");
//STEP 4: Execute a query
System.out.println("Creating statement...");
st = conn.createStatement();
String sql;
sql = "SELECT first, last FROM Employees";
ResultSet rs = st.executeQuery(sql);
//STEP 5: Extract data from result set
while(rs.next()){
//Retrieve by column name
String first = rs.getString("first");
String last = rs.getString("last");
//Display values
System.out.print(", First: " + first);
System.out.println(", Last: " + last);
}
//STEP 6: Clean-up environment
rs.close();
st.close();
conn.close();
}catch(SQLException se){
//Handle errors for JDBC
se.printStackTrace();
}catch(Exception e){
//Handle errors for Class.forName
e.printStackTrace();
}
finally
{
//finally block used to close resources
try{
if(st!=null)
st.close();
}catch(SQLException se2){
}// nothing we can do
try{
if(conn!=null)
conn.close();
}
catch(SQLException se){
se.printStackTrace();
}//end finally try
}
}

use 10.0.2.2 instead of localhost, it works for me.

You cannot directly use java.sql.DriverManger, Connection, etc in Android. Android support SQLite DB, if you want to use DB in android you have to go with SQLite database. For Postgres you have to develop server side application and api services which you can the call from Android

Okay, this may be obsolete but still helpful for users (it was helpful for me)
I copied your example and worked with it because I also need to get postgres running on android. And it works!
conn = DriverManager.getConnection("jdbc:postgresql://localhost:5432/","root","root");
This will result in an error because you need to enter the database name without a slash at the and, like:
conn = DriverManager.getConnection("jdbc:postgresql://domain.com:5432/databaseName", "username", "password");
Network connections (like connection to database) must be done in an AsyncTask using doInBackground(). I did it inside an activity
public class dbactivity extends AppCompatActivity { //sry code formatting just broke
String message = null;
String conmsg = null;
private class pgsqlcon extends AsyncTask<Void, Void, Void>
{
public pgsqlcon()
{
super();
}
#Override
protected Void doInBackground(Void... voids) {
Connection conn = null;
Statement st = null;
try
{
//STEP 2: Register JDBC driver
Class.forName("org.postgresql.Driver");
//STEP 3: Open a connection
System.out.println("Connecting to database...");
message = "Connecting to database...";
conn = DriverManager.getConnection("jdbc:postgresql://serverdomain.com:5432/databasename",
"dbusername", "password");
//and so on
If you need to make UI changes like setText, you must use runOnUiThread like so ():
//using quote because code formatting doesn't work anymore for me xD
private void setAsyncText(final TextView text,final String value){
runOnUiThread(new Runnable() {
#Override
public void run() {
if (value == null)
text.setText("null");
else
text.setText(value);
}
});
}
Oh yeah and last but not least, since I wrote this inside an Activiy, I have to trigger the trouble by calling my asynctask in OnCreate() of my Activity.
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_dbactivity);
pgsqlcon pgcon = new pgsqlcon();
pgcon.execute();
}
}
I am not that experienced by myself so you can use this only for getting a connection at all to your postgresdb using JDBC only. Although I managed to get successful query results that way.
And again, sorry for the wrong code formatting. I did what they wanted (4 space rule etc.) and it didn't work. I hope you can read it anyway, good luck.
And if nothing of this does work, maybeeee you want to take a look at these little hints: https://jdbc.postgresql.org/documentation/head/prepare.html
(I assume you did that anyway since you have done a lot of almost correct code)

My app uses PostgreSQL as backend. Use the retrofit library for connecting to the backend. In my app backend is written in python which will make queries in the database. This will make the front-end codes more smooth and secure. And the more controls can be shifted to the back-end.

You can not connect the database with android studio directly,
you have to make connection with your application and database through api ,
and you can write your api in java, php etc.
?php
$db_connection = pg_connect("host=localhost dbname=record user=postgres password= ''");
//pg query
?>
This is your connect query api.

Android : Listener for incoming UDP messages?

I have an application android who send data to the server (PC) but I don't receive any data from the PC to the application. And, how can I do a listener for incoming UDP messages ?
because I need an app to be running all the time even if the app is closed. How would I ensure that my 'listener' service is always running?
I would like to receive a notification when a message arrive from the server to the smartphone.
Here is my code :
public class MainActivity extends Activity implements TextWatcher, OnClickListener {
Client client;
EnvoyerMess envoyermessage;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
client = new Client();
client.execute();
lancer.setOnClickListener( new OnClickListener() {
#Override
public void onClick(View v) {
envoyermessage=new EnvoyerMess();
envoyermessage.execute();
}
});
}
class Client extends AsyncTask<Void,Void,String>{
DatagramSocket client;
String test ;
public String doInBackground(Void...params){
String result=null;
int port=4000;
DatagramSocket clientSocket = null;
byte[] receiveData = new byte[256];
DatagramPacket packet = new DatagramPacket(receiveData, receiveData.length);
try{
InetAddress adresse = InetAddress.getByName("10.0.2.2");
clientSocket = new DatagramSocket(port);
clientSocket.receive(packet);
result = new String(packet.getData());
Log.d("","Received :) ");
}catch (Exception e) {
e.printStackTrace();
} finally {
if (clientSocket != null) {
clientSocket.close();
}
}
return result;
}
public void onPostExecute(String result){
if (result != null) {
//createNotify();
TextView tv = (TextView) MainActivity.this.findViewById(R.id.textView1);
tv.setText(result);
}
}
thanks in advance..

I would start by ensuring that the PC is in fact sending the packets to the correct IP address. Do this by using wireshark, http://www.wireshark.org/ , or a similar tool.
To ensure that your task is running even though the application is is closed you need a service, http://developer.android.com/guide/components/services.html.
Edit:
I you are using an emulator you must first enable redirection in the avd router. This link provides instructions on how to accomplish this developer.android.com/tools/devices/emulator.html#redirection (I cant publish links so you'll have to copy-paste).
If you are developing in windows you would also need to enable telnet. This link describes the steps to accomplish that social.technet.microsoft.com/wiki/contents/articles/910.windows-7-enabling-telnet-client.aspx (again, copy-paste)

android application hangs when it connects to webservice using 3g connection and works fine with WIFI

I am developing an android application that consumes web service , the service output is XML
I am connecting to the web service using this code
public String converse(String host, int port, String path)
throws IOException, URISyntaxException {
BufferedReader in = null;
String serviceResponse = null ;
try {
HttpClient client = new DefaultHttpClient();
HttpGet request = new HttpGet();
String serviceUrl = "http://"+host+":"+port+path;
System.out.println("service url "+serviceUrl);
request.setURI(new URI(serviceUrl));
System.out.println("Request "+request.toString());
HttpResponse response = client.execute(request);
in = new BufferedReader
(new InputStreamReader(response.getEntity().getContent()));
StringBuffer sb = new StringBuffer("");
String line = "";
String NL = System.getProperty("line.separator");
while ((line = in.readLine()) != null) {
sb.append(line + NL);
}
in.close();
serviceResponse = sb.toString();
} finally {
if (in != null) {
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return serviceResponse;
}
when the application launches with WI-FI every thing works fine and when I restart the application with 3G connection it hangs and displays a the following dialog
In addition to this code I am using this method inside another method
public void fillAdapter() {
//calling web service using the mentioned method
}
And this function used inside an async task to fill ListView adapter
protected class AsyncLoading extends AsyncTask<Void,Void, BaseModel[]>{
#Override
protected void onPreExecute(){
pd =ProgressDialog.show(BaseListActivity.this, "loading in progress", "waiting .");
}
#Override
protected BaseModel[] doInBackground(Void... params) {
fillAdapter();
return listItems;
}
#Override
protected void onPostExecute(BaseModel[] doc){
//list.setAdapter(doc);
if(doc != null) {
if(doc.length > 0 ) {
if(doc[0] instanceof Activity)
adapter = new OffersListAdapter(getApplicationContext(),doc);
else if (doc[0] instanceof Offer)
adapter = new OffersListAdapter(getApplicationContext(),doc);
else if (doc[0] instanceof Branch) {
adapter = new BranchListAdapter(getApplicationContext(),doc);
Log.i("Branch"," Added Branch");
}else if (doc[0] instanceof Consolation) {
adapter = new ListAdapter(getApplicationContext(),doc);
adapter.setDisplayImage(false);
}else if ( doc[0] instanceof Event) {
adapter = new EventListAdapter(getApplicationContext(),doc);
}
else
adapter = new ListAdapter(getApplicationContext(),doc);
}//end if doc != null
list.setAdapter(adapter);
}
handler.sendEmptyMessage(0);
}
I saw this post but I don't have a good result I'm working on this problem for 2 days
with my thanks in advance .
Note : this problem often appears the first time the application connects to the service after that if I pressed wait and the application continued then al other activities consuming the web service will work fine

I think you have low speed connection of 3G compared to Wi-Fi.So Use Asynctask to load data from server in seperate thread rather than main thread.It is good idea to show ProgressDialog while fetching the data.
And In some cases Apis will work in Wi-Fi and may not in 3G connection.So test Your url in Device browser also to make it confirm

You should use an AsyncTask for every task that could take some time to be executed. See http://developer.android.com/reference/android/os/AsyncTask.html

The problem i am seeing with your code is you are not doing network operation in Thread.
So if you perform asynchronous operation on Main thread,application will display above dialog if it don't receive response in 5 seconds.In your case 3g connection may be taking more than 5 seconds to return response.
Best bet is include above code in Thread!!

I have solved the problem , that I have a splash screen activity inside which I use C2DM and register the device in that activity using service
registrationIntent.putExtra("app", PendingIntent.getBroadcast(getApplicationContext(), 0, new Intent(), 0));
registrationIntent.putExtra("sender", "someemailaddress#gmail.com");
startService(registrationIntent);
I put this code inside an asyncTask and didn't block the UI
Thanks for every one who tried to help me

android-json-rpc, receiving invalid response

I am trying to get responses from a JSON-RPC Service on Android, I'm currently developing on 3.0 Honeycomb.
This is the library I am using:
http://code.google.com/p/android-json-rpc/
and I am using this JSON-RPC service page for testing:
http://www.raboof.com/projects/jayrock/demo.ashx
The connection seems to work, but I keep getting this Exception
org.alexd.jsonrpc.JSONRPCException: Invalid JSON response
I've tried different methods and survey pages, but I always get the same Exception. Where am I going wrong?
The relevant code is below. AsyncTask is used because since 3.0 Android doesn't allow network connections in the main stream. Thanks in advance.
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
JSONHandler task = new JSONHandler();
task.execute(new String[] {"http://www.raboof.com/projects/jayrock/demo.ashx"});
}
private class JSONHandler extends AsyncTask<String, Void, String> {
#Override
protected String doInBackground(String... urls) {
for (String url : urls) {
JSONRPCClient client = JSONRPCClient.create(url);
client.setConnectionTimeout(2000);
client.setSoTimeout(2000);
try {
client.call("counter");
} catch (JSONRPCException e) {
e.printStackTrace(); //Invalid JSON Response caught here
}
}
return null;
}
}

I have tested your system using the last version of the library. It work great. You need to us callInt("counter") and it will be ok.
There is the code I used:
public JSONRPCClient client = JSONRPCClient.create("http://www.raboof.com/projects/jayrock/demo.ashx", JSONRPCClient.Versions.VERSION_2);
try{
int resInt = client.callInt("counter");
} catch (JSONException e) {
Log.i("JSON-RPC Client", e.toString());
}
I hope this can help.
PS: with this new version, you use parameters send as an array, or using a JSONObject to send named parameters. This is only possible if using the version 2.0 of the JSON-RPC protocol.

This is the only JSON-RPC client I've been able to get to work with Zend_Json_Server on Android (and I've tried a few).
Make sure to set the version to 2.0 also, as this client doesn't work unless your server is explicitly using the 2.0 spec:
$server = new Zend_Json_Server();
$server->setClass('My_Class');
$server->getRequest()->setVersion("2.0");
if ('GET' == $_SERVER['REQUEST_METHOD']) {
// Indicate the URL endpoint, and the JSON-RPC version used:
$server->setTarget('/ajax.php')
->setEnvelope(Zend_Json_Server_Smd::ENV_JSONRPC_2);
// Grab the SMD
$smd = $server->getServiceMap();
// Return the SMD to the client
header('Content-Type: application/json');
echo $smd;
return;
}
$server->handle();