Develop Reference

Running a background service which never stops (or always restarts)

I'm building an Android Wear service which runs in the background and logs device data every three minutes. For this logging, I am using a Handler, which records the values and then has an interval of three minutes. This will be used to monitor user behaviour for one month, and as such it should not randomly stop.
I have also used android.intent.action.BOOT_COMPLETED in my manifest and this successfully runs the application whenever the watch is booted.
My issue is that the service can run correctly for 12 hours...and then just suddenly stop. The amount of time appears to be non-deterministic, as sometimes it will stop after 40 minutes. I suspect it's being killed by Android, but in this case I would like it to restart. I have included return START_STICKY in my service and this should minimise the chance of it being killed.
In some solutions, I have seen onDestroy() overridden and a refresh broadcast being sent to the service. While this appears to work, the onDestroy() function is being called every time the Handler completes one piece of work. This leads to the service restarting every three minutes, rather than when the application is actually killed by Android.
I have also looked at the intent actions to see whether my service could be called at regular intervals. However, aside from android.intent.action.BOOT_COMPLETED, all the useful ones cannot be registered in the Manifest file. Since the service will not be running, registerReceiver() would serve little purpose.
Does anybody know of a technique to either a) guarantee a service will not be killed by Android; or b) guarantee that a service will always be restarted after it has been killed. Any help would be greatly appreciated, as I've even started considering writing a Cron job on the device and setting it to execute my app every three minutes! I've also looked at the AlarmManager class, but I fear it is as likely to be killed if running for long periods.
Please find my code below: (AndroidManifest.xml)
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.study">
<uses-feature android:name="android.hardware.type.watch" />
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:supportsRtl="true"
android:theme="#android:style/Theme.DeviceDefault">
<receiver android:name="com.example.study.MyServiceManager" android:enabled="true">
<intent-filter>
<action android:name="com.example.study.RestartAction" />
<action android:name="android.intent.action.BOOT_COMPLETED" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</receiver>
<activity
android:name="com.example.study.MainActivity"
android:label="#string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<service
android:name="com.example.study.RecordService"
android:exported="false" />
</application>
</manifest>
RecordService.java
package com.example.study;
import android.Manifest;
import android.app.AlarmManager;
import android.app.IntentService;
import android.app.KeyguardManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.location.Location;
import com.google.android.gms.location.LocationServices;
import android.os.Build;
import android.os.Handler;
import android.os.PowerManager;
import android.provider.Settings;
import android.support.annotation.Nullable;
import android.support.v4.app.ActivityCompat;
import android.text.TextUtils;
import com.google.android.gms.location.*;
import com.google.android.gms.tasks.OnSuccessListener;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.concurrent.ExecutionException;
public class RecordService extends IntentService {
private static Context context;
private final static int INTERVAL = 1000 * 5; // 1 minutes
Handler handler = new Handler();
Location myLocation;
private FusedLocationProviderClient mFusedLocationClient;
SensorManager sensorManager;
SensorManager gyroSensorManager;
SensorManager compassSensorManager;
SensorEventListener sensorEventListener;
float[] accValues;
float[] gyroValues;
float[] compassValues;
Runnable handlerTask = new Runnable() {
#Override
public void run() {
try {
recordData();
} catch (ExecutionException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
handler.postDelayed(handlerTask, INTERVAL);
}
};
public RecordService() {
super("RecordService");
}
#Override
protected void onHandleIntent(#Nullable Intent intent) {
handlerTask.run();
}
public int onStartCommand(Intent intent, int flags, int startId) {
super.onStartCommand(intent, flags, startId);
return START_STICKY;
}
public void recordData() throws ExecutionException, InterruptedException {
mFusedLocationClient = LocationServices.getFusedLocationProviderClient(MainActivity.getAppContext());
boolean fineLocationGranted = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED;
boolean coarseLocationGranted = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED;
boolean isLocationEnabled = isLocationEnabled(this);
if(fineLocationGranted && coarseLocationGranted && isLocationEnabled) {
long startTime = System.currentTimeMillis();
long timeWaiting = 0L;
mFusedLocationClient.getLastLocation()
.addOnSuccessListener(MainActivity.getActivity(), new OnSuccessListener<Location>() {
#Override
public void onSuccess(Location location) {
if (location != null) {
myLocation = location;
} else {
System.out.print("");
}
}
});
do {
timeWaiting = System.currentTimeMillis() - startTime;
} while (myLocation == null && timeWaiting < 200);
}
List<PackageInfo> packages = getPackageManager().getInstalledPackages(PackageManager.GET_PERMISSIONS);
KeyguardManager kg = (KeyguardManager) getSystemService(Context.KEYGUARD_SERVICE);
boolean isLocked = kg.isDeviceSecure();
sensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
gyroSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
compassSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
sensorEventListener = new SensorEventListener() {
#Override
public void onSensorChanged(SensorEvent sensorEvent) {
if(sensorEvent.sensor.getType() == Sensor.TYPE_ACCELEROMETER) {
accValues = sensorEvent.values;
} else if(sensorEvent.sensor.getType() == Sensor.TYPE_GYROSCOPE){
gyroValues = sensorEvent.values;
} else if(sensorEvent.sensor.getType() == Sensor.TYPE_ORIENTATION) {
compassValues = sensorEvent.values;
}
}
#Override
public void onAccuracyChanged(Sensor sensor, int i) {}
};
try {
sensorManager.registerListener(sensorEventListener, sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_NORMAL);
gyroSensorManager.registerListener(sensorEventListener, sensorManager.getDefaultSensor(Sensor.TYPE_GYROSCOPE), SensorManager.SENSOR_DELAY_NORMAL);
compassSensorManager.registerListener(sensorEventListener, sensorManager.getDefaultSensor(Sensor.TYPE_ORIENTATION), SensorManager.SENSOR_DELAY_NORMAL);
} catch(SecurityException e) {
e.printStackTrace();
}
long startTime2 = System.currentTimeMillis();
long timeWaiting2 = 0L;
do {
timeWaiting2 = System.currentTimeMillis() - startTime2;
} while((accValues == null || gyroValues == null || compassValues == null) && timeWaiting2 < 200);
StringBuilder builder = new StringBuilder();
builder.append("G" + (isLocationEnabled ? 1 : 0));
builder.append(" L" + (isLocked ? 1 : 0));
if(accValues != null && gyroValues != null && compassValues != null) {
builder.append(" ACX" + accValues[0]);
builder.append(" ACY" + accValues[1]);
builder.append(" ACZ" + accValues[2]);
builder.append(" GYX" + gyroValues[0]);
builder.append(" GYY" + gyroValues[1]);
builder.append(" GYZ" + gyroValues[2]);
builder.append(" CMX" + gyroValues[0]);
builder.append(" CMY" + gyroValues[1]);
builder.append(" CMZ" + gyroValues[2]);
}
if(myLocation != null) {
builder.append(" LT" + myLocation.getLatitude());
builder.append(" LN" + myLocation.getLongitude());
}
builder.append("\n");
for(PackageInfo info: packages) {
int lastDot = info.packageName.lastIndexOf('.');
builder.append(info.packageName + "\n");
if(info.requestedPermissions != null) {
for (String rqprm : info.requestedPermissions) {
int dot = rqprm.lastIndexOf('.');
builder.append(rqprm.substring(dot != -1 ? dot + 1 : 0) + " ");
}
builder.append("\n");
for (int permflag : info.requestedPermissionsFlags) {
builder.append("" + permflag + " ");
}
builder.append("\n");
}
}
SimpleDateFormat sdf = new SimpleDateFormat("yy-MM-dd--HH-mm-ss");
String currentDateString = sdf.format(new Date());
File log = new File("/sdcard/Recordings/" + currentDateString);
try {
if (!log.exists()) {
log.createNewFile();
}
BufferedWriter writer = new BufferedWriter(new FileWriter(log, true));
writer.append(builder.toString());
writer.newLine();
writer.close();
} catch (IOException e) {
e.printStackTrace();
}
}
public static boolean isLocationEnabled(Context context) {
int locationMode = 0;
String locationProviders;
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT){
try {
locationMode = Settings.Secure.getInt(context.getContentResolver(), Settings.Secure.LOCATION_MODE);
} catch (Settings.SettingNotFoundException e) {
e.printStackTrace();
return false;
}
return locationMode != Settings.Secure.LOCATION_MODE_OFF;
} else {
locationProviders = Settings.Secure.getString(context.getContentResolver(), Settings.Secure.LOCATION_PROVIDERS_ALLOWED);
return !TextUtils.isEmpty(locationProviders);
}
}
MainActivity.java
package com.example.study;
import android.app.Activity;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;
public class MainActivity extends Activity {
private TextView mTextView;
private static Context context;
private static MainActivity activity;
Intent serviceIntent;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
MainActivity.context = getApplicationContext();
activity = this;
serviceIntent = new Intent(this, RecordService.class);
startForegroundService(serviceIntent)
startService(serviceIntent);
}
public static Context getAppContext() {
return MainActivity.context;
}
public static MainActivity getActivity() {
return activity;
}
}
MyServiceManager.java
package com.example.study;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
public class MyServiceManager extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
Intent myIntent = new Intent(context, MainActivity.class);
myIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(myIntent);
}
}
}

UDP Client on Android

I have made an UDP Server on a Wi-Fi demo board and test it using and android App (UDP Sender).
I created my own UDP client apps on Android, but it doesn't work.
I created and configured well the socket port and the IPaddress but the app doesn't work and I don't know why.
PS : In the manifest I added the uses-permission to access to the Wi-Fi
her is my simple code
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class Udp_Client extends Activity {
/** Called when the activity is first created. */
TextView txt5,txt1;
byte[] send_data = new byte[1024];
Button hello;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
txt1 = (TextView)findViewById(R.id.textView1);
txt5 = (TextView)findViewById(R.id.textView5);
hello = (Button) findViewById(R.id.button1);
hello.setOnClickListener(new View.OnClickListener(){
public void onClick(View v) {
try {
client();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});
}
public void client() throws IOException{
String str="Hello";
int port = 50000;
DatagramSocket client_socket = new DatagramSocket(port);
InetAddress IPAddress = InetAddress.getByName("192.168.0.1");
send_data = str.getBytes();
DatagramPacket send_packet = new DatagramPacket(send_data,str.length(), IPAddress, port);
//client_socket.setBroadcast(true);
client_socket.send(send_packet);
client_socket.close();
}
}
[1]: http://i.stack.imgur.com/aXPhf.png

I found the solution for the problem
The problem was in the manifest
Here is my new code and my manifest
The main in wich I call the UDP_Client :
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends ActionBarActivity implements View.OnClickListener {
private TextView sceen = null;
private Button launch = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
sceen = (TextView)findViewById(R.id.textView1);
launch = (Button)findViewById(R.id.udpbutton);
launch.setOnClickListener(this);
launch.setOnClickListener((OnClickListener) this);
}
public void onClick(View v) {
//UDP Client erstellen
UDP_Client Client = new UDP_Client();
Client.Message = "Your message";
Client.NachrichtSenden();
}
}
The code of my UDP_Client
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import android.annotation.SuppressLint;
import android.os.AsyncTask;
import android.os.Build;
public class UDP_Client
{
private InetAddress IPAddress = null;
private String message = "Hello Android!" ;
private AsyncTask<Void, Void, Void> async_cient;
public String Message;
#SuppressLint("NewApi")
public void NachrichtSenden()
{
async_cient = new AsyncTask<Void, Void, Void>()
{
#Override
protected Void doInBackground(Void... params)
{
DatagramSocket ds = null;
try
{
byte[] ipAddr = new byte[]{ (byte) 192, (byte) 168,43, (byte) 157};
InetAddress addr = InetAddress.getByAddress(ipAddr);
ds = new DatagramSocket(5000);
DatagramPacket dp;
dp = new DatagramPacket(Message.getBytes(), Message.getBytes().length, addr, 50000);
ds.setBroadcast(true);
ds.send(dp);
}
catch (Exception e)
{
e.printStackTrace();
}
finally
{
if (ds != null)
{
ds.close();
}
}
return null;
}
protected void onPostExecute(Void result)
{
super.onPostExecute(result);
}
};
if (Build.VERSION.SDK_INT >= 11) async_cient.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
else async_cient.execute();
}
}
The manifest :
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.udp_server"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="21" />
<uses-permission android:name="android.permission.INTERNET" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
I added the part of code in my manifest
hope that it will help someone in the future ;)

I think you miss this:
public void connect (InetAddress address, int port)
Of the DataGramSocket Object.
Try:
client_socket.connect(IPAddress, port);
client_socket.send(send_packet);

Download and install android app [duplicate]

This question already has answers here:
Install Application programmatically on Android
(18 answers)
Closed 9 years ago.
In my android app i have 1 button to download the .apk and and then im adding another to install the .apk, when you click the download button it downloads the .apk from my website and puts it in the root of your sdcard storage! what do i have to add so when the user clicks the button named "install" it takes them to the install screen??
MainActvity.java
package cydia.jb.download;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import android.app.Activity;
import android.app.Dialog;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.view.Window;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity {
ProgressBar pb;
Dialog dialog;
int downloadedSize = 0;
int totalSize = 0;
TextView cur_val;
String dwnload_file_path = "http://diordnakclab.net23.net/cydia/Cydia.apk";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button b = (Button) findViewById(R.id.button1);
b.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
showProgress(dwnload_file_path);
new Thread(new Runnable() {
public void run() {
downloadFile();
}
}).start();
}
});
}
void downloadFile(){
try {
URL url = new URL(dwnload_file_path);
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.setDoOutput(true);
//connect
urlConnection.connect();
//set the path where we want to save the file
File SDCardRoot = Environment.getExternalStorageDirectory();
//create a new file, to save the downloaded file
File file = new File(SDCardRoot,"Cydia.apk");
FileOutputStream fileOutput = new FileOutputStream(file);
//Stream used for reading the data from the internet
InputStream inputStream = urlConnection.getInputStream();
//this is the total size of the file which we are downloading
totalSize = urlConnection.getContentLength();
runOnUiThread(new Runnable() {
public void run() {
pb.setMax(totalSize);
}
});
//create a buffer...
byte[] buffer = new byte[1024];
int bufferLength = 0;
while ( (bufferLength = inputStream.read(buffer)) > 0 ) {
fileOutput.write(buffer, 0, bufferLength);
downloadedSize += bufferLength;
// update the progressbar //
runOnUiThread(new Runnable() {
public void run() {
pb.setProgress(downloadedSize);
float per = ((float)downloadedSize/totalSize) * 100;
cur_val.setText("Downloaded " + downloadedSize + "KB / " + totalSize + "KB (" + (int)per + "%)" );
}
});
}
//close the output stream when complete //
fileOutput.close();
runOnUiThread(new Runnable() {
public void run() {
// pb.dismiss(); // if you want close it..
}
});
} catch (final MalformedURLException e) {
showError("Error : MalformedURLException " + e);
e.printStackTrace();
} catch (final IOException e) {
showError("Error : IOException " + e);
e.printStackTrace();
}
catch (final Exception e) {
showError("Error : Please check your internet connection " + e);
}
}
void showError(final String err){
runOnUiThread(new Runnable() {
public void run() {
Toast.makeText(MainActivity.this, err, Toast.LENGTH_LONG).show();
}
});
}
void showProgress(String file_path){
dialog = new Dialog(MainActivity.this);
dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
dialog.setContentView(R.layout.myprogressdialog);
dialog.setTitle("Download Progress");
TextView text = (TextView) dialog.findViewById(R.id.tv1);
text.setText("Downloading file from ... " + file_path);
cur_val = (TextView) dialog.findViewById(R.id.cur_pg_tv);
cur_val.setText("Starting download...");
dialog.show();
pb = (ProgressBar)dialog.findViewById(R.id.progress_bar);
pb.setProgress(0);
pb.setProgressDrawable(getResources().getDrawable(R.drawable.green_progress));
}
}
CydiaManafest
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="cydia.jb.download"
android:versionCode="4"
android:versionName="4.0" >
<uses-sdk
android:minSdkVersion="16"
android:targetSdkVersion="17" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="cydia.jb.download.MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>

here is the code
button1 = (Button) findViewById(R.id.button1);
button1.setOnClickListener(new OnClickListener()
{
public void onClick(View v1)
{
Intent promptInstall = new Intent(Intent.ACTION_VIEW)
.setData(Uri.parse("file:///path/to/your.apk"))
.setType("application/vnd.android.package-archive");
startActivity(promptInstall);
}
}

NFC Intent Filter - Sending Message Non-Main Activity

I am sure this is simple but I cannot figure it out. All I am trying to do is send a message via NFC. The code I have work perfectly if I am sending it to the main activity, but I don't know how to send it to a different activity. I have looked over both the NFC and Intent Filter articles on the Android Developer pages but am still not sure exactly how to do this. I am trying to send it to a NFC activity, I will post my manifest and NFC class below.
Manifest:
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.justbaumdev.tagsense"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="16"
android:targetSdkVersion="15" />
<uses-permission android:name="android.permission.NFC" />
<uses-feature android:name="android.hardware.nfc" />
<application
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#android:style/Theme.Holo" >
<activity
android:name=".TagSense"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name="com.justbaumdev.tagsense.NFC" android:exported="false">
<intent-filter>
<action android:name="android.nfc.action.NDEF_DISCOVERED" />
<category android:name="android.intent.category.DEFAULT" />
<data android:mimeType="application/com.justbaumdev.tagsense" />
</intent-filter>
</activity>
</application>
</manifest>
NFC Class:
package com.justbaumdev.tagsense;
import org.json.JSONArray;
import org.json.JSONException;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.net.wifi.WifiManager;
import android.nfc.NdefMessage;
import android.nfc.NdefRecord;
import android.nfc.NfcAdapter;
import android.nfc.NfcAdapter.CreateNdefMessageCallback;
import android.nfc.NfcAdapter.OnNdefPushCompleteCallback;
import android.nfc.NfcEvent;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.os.Parcelable;
import android.widget.Toast;
public class NFC extends Activity implements CreateNdefMessageCallback, OnNdefPushCompleteCallback {
private NfcAdapter mNfcAdapter;
private static final int MESSAGE_SENT = 1;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.nfc);
mNfcAdapter = NfcAdapter.getDefaultAdapter(this); // Check for available NFC Adapter
if (mNfcAdapter == null)
{
Toast.makeText(this, "NFC is not available", Toast.LENGTH_LONG).show();
finish();
return;
}
else
{
mNfcAdapter.setNdefPushMessageCallback(this, this); // Register callback to set NDEF message
mNfcAdapter.setOnNdefPushCompleteCallback(this, this); // Register callback to listen for message-sent success
}
}
#Override
public void onResume() {
super.onResume();
// Check to see that the Activity started due to an Android Beam
if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(getIntent().getAction())) {
processIntent(getIntent());
}
}
#Override
public void onNewIntent(Intent intent) {
// onResume gets called after this to handle the intent
setIntent(intent);
}
#Override
public NdefMessage createNdefMessage(NfcEvent event) {
WifiManager wm = (WifiManager) getSystemService(Context.WIFI_SERVICE);
String mac = wm.getConnectionInfo().getMacAddress();
String newMac = mac.substring(0, 2);
mac = mac.substring(2);
int hex = Integer.parseInt(newMac, 16) + 0x2;
newMac = Integer.toHexString(hex);
String text = newMac + mac;
NdefMessage msg = new NdefMessage(NdefRecord.createMime(
"application/com.justbaumdev.tagsense", text.getBytes()));
return msg;
}
/**
* Implementation for the OnNdefPushCompleteCallback interface
*/
#Override
public void onNdefPushComplete(NfcEvent arg0) {
// A handler is needed to send messages to the activity when this
// callback occurs, because it happens from a binder thread
mHandler.obtainMessage(MESSAGE_SENT).sendToTarget();
}
/** This handler receives a message from onNdefPushComplete */
private final Handler mHandler = new Handler() {
#Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MESSAGE_SENT:
Toast.makeText(getApplicationContext(), "Message sent!", Toast.LENGTH_LONG).show();
break;
}
}
};
/**
* Parses the NDEF Message from the intent and prints to the TextView
*/
//TODO Currently overwrites any previously saved mac addresses. Get FB ID as value. Auto end activity.
void processIntent(Intent intent) {
Parcelable[] rawMsgs = intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
// only one message sent during the beam
NdefMessage msg = (NdefMessage) rawMsgs[0];
// record 0 contains the MIME type, record 1 is the AAR, if present
//textView.setText(new String(msg.getRecords()[0].getPayload()));
String payload = new String(msg.getRecords()[0].getPayload());
Toast.makeText(this, new String(msg.getRecords()[0].getPayload()), Toast.LENGTH_LONG).show();
SharedPreferences appData = getSharedPreferences("appData", Context.MODE_PRIVATE);
SharedPreferences.Editor editor = appData.edit();
String addresses = appData.getString("mac_address", null);
if(addresses==null)
{
JSONArray addressArray = new JSONArray();
addressArray.put(payload);
addresses = addressArray.toString();
}
else
{
try {
if(!addresses.contains(payload))
{
JSONArray addressArray = new JSONArray(addresses);
addressArray.put(payload);
addresses = addressArray.toString();
}
} catch (JSONException e) {
Toast.makeText(this, "Error adding new friend. Please try again.", Toast.LENGTH_SHORT).show();
}
}
editor.putString("mac_address", addresses);
editor.commit();
}
}
Thanks for your help.

Remove the attribute android:exported="false". See also https://stackoverflow.com/a/12719621/1202968

how to create Socket connection in Android?

I have an application in which I need to create a socket connection. My requirement is: once my socket connection is established it needs to be alive until I personally close it. And every 3 minutes I have to send data packets to the other end. Can anyone provide me some code samples that will help me to do this?

Socket connections in Android are the same as in Java: http://www.oracle.com/technetwork/java/socket-140484.html
Things you need to be aware of:
If phone goes to sleep your app will no longer execute, so socket will eventually timeout. You can prevent this with wake lock. This will eat devices battery tremendously - I know I wouldn't use that app.
If you do this constantly, even when your app is not active, then you need to use Service.
Activities and Services can be killed off by OS at any time, especially if they are part of an inactive app.
Take a look at AlarmManager, if you need scheduled execution of your code.
Do you need to run your code and receive data even if user does not use the app any more (i.e. app is inactive)?

Here, in this post you will find the detailed code for establishing socket between devices or between two application in the same mobile.
You have to create two application to test below code.
In both application's manifest file, add below permission
<uses-permission android:name="android.permission.INTERNET" />
1st App code: Client Socket
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TableRow
android:id="#+id/tr_send_message"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_marginTop="11dp">
<EditText
android:id="#+id/edt_send_message"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:layout_marginRight="10dp"
android:layout_marginLeft="10dp"
android:hint="Enter message"
android:inputType="text" />
<Button
android:id="#+id/btn_send"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginRight="10dp"
android:text="Send" />
</TableRow>
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_below="#+id/tr_send_message"
android:layout_marginTop="25dp"
android:id="#+id/scrollView2">
<TextView
android:id="#+id/tv_reply_from_server"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical" />
</ScrollView>
</RelativeLayout>
MainActivity.java
import android.os.Bundle;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.Socket;
/**
* Created by Girish Bhalerao on 5/4/2017.
*/
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private TextView mTextViewReplyFromServer;
private EditText mEditTextSendMessage;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button buttonSend = (Button) findViewById(R.id.btn_send);
mEditTextSendMessage = (EditText) findViewById(R.id.edt_send_message);
mTextViewReplyFromServer = (TextView) findViewById(R.id.tv_reply_from_server);
buttonSend.setOnClickListener(this);
}
#Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.btn_send:
sendMessage(mEditTextSendMessage.getText().toString());
break;
}
}
private void sendMessage(final String msg) {
final Handler handler = new Handler();
Thread thread = new Thread(new Runnable() {
#Override
public void run() {
try {
//Replace below IP with the IP of that device in which server socket open.
//If you change port then change the port number in the server side code also.
Socket s = new Socket("xxx.xxx.xxx.xxx", 9002);
OutputStream out = s.getOutputStream();
PrintWriter output = new PrintWriter(out);
output.println(msg);
output.flush();
BufferedReader input = new BufferedReader(new InputStreamReader(s.getInputStream()));
final String st = input.readLine();
handler.post(new Runnable() {
#Override
public void run() {
String s = mTextViewReplyFromServer.getText().toString();
if (st.trim().length() != 0)
mTextViewReplyFromServer.setText(s + "\nFrom Server : " + st);
}
});
output.close();
out.close();
s.close();
} catch (IOException e) {
e.printStackTrace();
}
}
});
thread.start();
}
}
2nd App Code - Server Socket
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button
android:id="#+id/btn_stop_receiving"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="STOP Receiving data"
android:layout_alignParentTop="true"
android:enabled="false"
android:layout_centerHorizontal="true"
android:layout_marginTop="89dp" />
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="#+id/btn_stop_receiving"
android:layout_marginTop="35dp"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true">
<TextView
android:id="#+id/tv_data_from_client"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical" />
</ScrollView>
<Button
android:id="#+id/btn_start_receiving"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="START Receiving data"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="14dp" />
</RelativeLayout>
MainActivity.java
import android.os.Bundle;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
/**
* Created by Girish Bhalerao on 5/4/2017.
*/
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
final Handler handler = new Handler();
private Button buttonStartReceiving;
private Button buttonStopReceiving;
private TextView textViewDataFromClient;
private boolean end = false;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
buttonStartReceiving = (Button) findViewById(R.id.btn_start_receiving);
buttonStopReceiving = (Button) findViewById(R.id.btn_stop_receiving);
textViewDataFromClient = (TextView) findViewById(R.id.tv_data_from_client);
buttonStartReceiving.setOnClickListener(this);
buttonStopReceiving.setOnClickListener(this);
}
private void startServerSocket() {
Thread thread = new Thread(new Runnable() {
private String stringData = null;
#Override
public void run() {
try {
ServerSocket ss = new ServerSocket(9002);
while (!end) {
//Server is waiting for client here, if needed
Socket s = ss.accept();
BufferedReader input = new BufferedReader(new InputStreamReader(s.getInputStream()));
PrintWriter output = new PrintWriter(s.getOutputStream());
stringData = input.readLine();
output.println("FROM SERVER - " + stringData.toUpperCase());
output.flush();
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
updateUI(stringData);
if (stringData.equalsIgnoreCase("STOP")) {
end = true;
output.close();
s.close();
break;
}
output.close();
s.close();
}
ss.close();
} catch (IOException e) {
e.printStackTrace();
}
}
});
thread.start();
}
private void updateUI(final String stringData) {
handler.post(new Runnable() {
#Override
public void run() {
String s = textViewDataFromClient.getText().toString();
if (stringData.trim().length() != 0)
textViewDataFromClient.setText(s + "\n" + "From Client : " + stringData);
}
});
}
#Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.btn_start_receiving:
startServerSocket();
buttonStartReceiving.setEnabled(false);
buttonStopReceiving.setEnabled(true);
break;
case R.id.btn_stop_receiving:
//stopping server socket logic you can add yourself
buttonStartReceiving.setEnabled(true);
buttonStopReceiving.setEnabled(false);
break;
}
}
}

Simple socket server app example
I've already posted a client example at: https://stackoverflow.com/a/35971718/895245 , so here goes a server example.
This example app runs a server that returns a ROT-1 cypher of the input.
You would then need to add an Exit button + some sleep delays, but this should get you started.
To play with it:
install the app
get your phone and PC on a LAN
find your phone's IP with https://android.stackexchange.com/a/130468/126934
run netcat $PHONE_IP 12345
type some lines
Android sockets are the same as Java's, except we have to deal with some permission issues.
src/com/cirosantilli/android_cheat/socket/Main.java
package com.cirosantilli.android_cheat.socket;
import android.app.Activity;
import android.app.IntentService;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.net.ServerSocket;
import java.net.Socket;
public class Main extends Activity {
static final String TAG = "AndroidCheatSocket";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.d(Main.TAG, "onCreate");
Main.this.startService(new Intent(Main.this, MyService.class));
}
public static class MyService extends IntentService {
public MyService() {
super("MyService");
}
#Override
protected void onHandleIntent(Intent intent) {
Log.d(Main.TAG, "onHandleIntent");
final int port = 12345;
ServerSocket listener = null;
try {
listener = new ServerSocket(port);
Log.d(Main.TAG, String.format("listening on port = %d", port));
while (true) {
Log.d(Main.TAG, "waiting for client");
Socket socket = listener.accept();
Log.d(Main.TAG, String.format("client connected from: %s", socket.getRemoteSocketAddress().toString()));
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
PrintStream out = new PrintStream(socket.getOutputStream());
for (String inputLine; (inputLine = in.readLine()) != null;) {
Log.d(Main.TAG, "received");
Log.d(Main.TAG, inputLine);
StringBuilder outputStringBuilder = new StringBuilder("");
char inputLineChars[] = inputLine.toCharArray();
for (char c : inputLineChars)
outputStringBuilder.append(Character.toChars(c + 1));
out.println(outputStringBuilder);
}
}
} catch(IOException e) {
Log.d(Main.TAG, e.toString());
}
}
}
}
We need a Service or other background method or else: How do I fix android.os.NetworkOnMainThreadException?
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.cirosantilli.android_cheat.socket"
android:versionCode="1"
android:versionName="1.0">
<uses-sdk android:minSdkVersion="22" />
<uses-permission android:name="android.permission.INTERNET" />
<application android:label="AndroidCheatsocket">
<activity android:name="Main">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<service android:name=".Main$MyService" />
</application>
</manifest>
We must add: <uses-permission android:name="android.permission.INTERNET" /> or else: Java socket IOException - permission denied
On GitHub with a build.xml: https://github.com/cirosantilli/android-cheat/tree/92de020d0b708549a444ebd9f881de7b240b3fbc/socket