How can i Implement a reward system in android programatically? [closed] - android

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I am planning on implementing a reward system in my android application where users of the application can gain 100 points each day for opening the app. Users can only get 100 points at one given day no matter how many times more then once they open the app. I am not sure how I can go about doing this, for example, a application called WhatsChat, give users credits for opening the app each day:
I am trying to implement a similar system but instead only give users 100 points for opening the app each day. I understand I will need to keep track of the day and maybe store this in local storage using SharedPreferences and keep record of the dates of each day and then increments the variable that records points by 100.
In pseudo code it would look something like this:
Set CreditsGained to 0
IF app launched for the first time on Current date THEN
CreditsGained = CreditsGained + 100
Else
Do nothing
How can I implement a such system in my application?

You do it on the server. The first time they make a network request every day, add 100 points to their total. There's no way to do this securely client side.

I recommend you not use Shared Preferences to save data like you want. Cos they can modify it.
Only 1 way you can secure it, you have to have your own server to keep it. Local storage is not safe too.
But if you want to know how to check that, for studying, you can use Shared Preferences as well.
Step1: get your current time in string:
SimpleDateFormat sdf = new SimpleDateFormat("d-m-Y");
Calendar cal = Calendar.getInstance();
String dateInStr = sdf.format(cal.getTime());
Step2: Check at startup activity.
After onCreate()
SharedPreferences pre=getSharedPreferences("my_sp", MODE_PRIVATE);
SharedPreferences.Editor edit=pre.edit();
if (pre.getBoolean(dateInStr, false)){
//they checked today
}else{
//not today
// use check function here
edit.putBoolean(dateInStr, true);
edit.commit();
}
Okay, put step 1 code above step 2 code, i only separate it for easier understanding.
Step3: After you can check if they have check point more than 1 time or not. Let's add them 100points if that is the first time of the day they check out.
Put this inside else statement, above edit.putBoolean(dateInStr, true);
//get prev_score from SP
long previous_score = pre.getLong("score", 0);
//add 100
previous_score = previous_score + 100;
//save back to SP
edit.putLong("score", previous_score);

I may be late answering to your question..but for others seeking for the reward system and do not want the servers to handle this stuff -->
You can
check whether the Automatic Date and time option is enabled or not in
the user's device
**. Then according to the response, you can give reward to the user.
eg.
calendar= Calendar.getInstance();
year=calendar.get(Calendar.YEAR);
month=calendar.get(Calendar.MONTH);
day=calendar.get(Calendar.DAY_OF_MONTH);
todaystring= year+ "" + month + "" + day + "";
timepref=context.getSharedPreferences("REWARD",0);
currentday=timepref.getBoolean(todaystring,false);
//Daily reward
if (!currentday && isZoneAutomatic(context) && isTimeAutomatic(context)) { //currentday =false
btnrwrd.setEnabled(true);
btnrwrd.setText("Collect your daily reward!");
btnrwrd.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Toast.makeText(context, "Daily reward granted!", Toast.LENGTH_SHORT).show();
// Do your stuff here
// saving the date
SharedPreferences sharedPreferences = context.getSharedPreferences("SAVING", Context.MODE_PRIVATE);
SharedPreferences.Editor edt = sharedPreferences.edit();
edt.putInt("mypoints", Integer.valueOf(points.getText().toString()));
edt.apply();
Toast.makeText(context, String.valueOf(daily), Toast.LENGTH_SHORT).show();
SharedPreferences.Editor timedaily = timepref.edit();
timedaily.putBoolean(todaystring, true);
timedaily.apply();
btnrwrd.setText("Wait for 24 hrs");
btnrwrd.setEnabled(false);
}
});
}
else {
Toast.makeText(context, "Your daily reward is over!", Toast.LENGTH_SHORT).show();
}
public static boolean isTimeAutomatic(Context c) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
return Settings.Global.getInt(c.getContentResolver(), Settings.Global.AUTO_TIME, 0) == 1;
} else {
return android.provider.Settings.System.getInt(c.getContentResolver(), android.provider.Settings.System.AUTO_TIME, 0) == 1;
}
}
public static boolean isZoneAutomatic(Context c) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
return Settings.Global.getInt(c.getContentResolver(), Settings.Global.AUTO_TIME_ZONE, 0) == 1;
} else {
return android.provider.Settings.System.getInt(c.getContentResolver(), android.provider.Settings.System.AUTO_TIME, 0) == 1;
}
}
I hope it helps you! Upvote the answer and Good luck :)

Whenever the user opens the app, check if any last credit date is available in the local storage and if it does, verify the current date is one more than the stored date, then you credit the user for next day.
If the date is not available in storage, then you can assume it's the first day. And yes you can do it in MainActivity for this use case because you are not making any time consuming api calls.
I just shared the idea, figure out the code. It's easy.

Related

How to show AlertDialog within Override function?

Last week I started learning Android as I needed to create an application for one of the projects at Uni.
The application is a simple barcode/QRcode scanner and it should scan the code, compare its result with the database (I'm using Firebase) and either return other data from database if the barcode is found or ask the user if he wants to add the barcode to the database if it's not found.
I thought the easiest way to do it would be to use AlertDialog, but the app crashes every single time I scan the code.
I debugged the app and checked the Logcat, what I get is:
You need to use a Theme.AppCompat theme (or descendant) with this activity.
This is exactly where I get the error and where I wanted to use AlertDialog - based on the value in the variable details.
private BarcodeCallback callback = new BarcodeCallback() {
#Override
public void barcodeResult(final BarcodeResult result) {
barcodeView.decodeSingle(callback);
dbRef.child("Items").addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
Iterator<DataSnapshot> item = dataSnapshot.getChildren().iterator();
Boolean isFound = false;
while (!isFound || item == null) {
DataSnapshot i = item.next();
String check = i.child("ID").getValue().toString();
if (result.getText().equals(check)) {
isFound = true;
details = "Consumption: " + i.child("Consumption").getValue().toString()
+ "\nCost: " + i.child("Cost").getValue().toString()
+ "\nName: " + i.child("Name").getValue().toString();
} else {
details = "Not found";
}
}
new AlertDialog.Builder(getApplicationContext())
.setMessage("This is just an example for the purpose of the question.")
.create()
.show();
}
I get the error exactly on the line with .show();.
In the previous posts I found that you can't display AlertDialog in this place, and you need to use runOnUiThread function or Handler, none of those options worked for me, and I was getting the error in the same place.
Do you guys have any advice or suggestions?
Also, I'm sorry for the way this post looks like or for any missing but required information. I know it's not an excuse, but this is my first post here.
Thanks in advance for any replies.
The problem is here:
new AlertDialog.Builder(getApplicationContext())
You can't build a Dialog using the application context. To reach this you need an Activity Context.
Read this question or this article for further understanding

Google play services leader board not showing

I have it showing fine for one leader board, whatever board, I call it by itself. When I want to show all of the boards I make the call below. It shows the last board called only. I understand this, what I want to know is there a way to just call the leader boards without calling one at a time so the user can compare the scores to each other?
private void signToLeaderBoard() {
if (mGoogleApiClient.isConnected()) {
startActivityForResult(Games.Leaderboards.getLeaderboardIntent(mGoogleApiClient,
context.getString(R.string.leaderboard_game_high_score)), 1);
startActivityForResult(Games.Leaderboards.getLeaderboardIntent(mGoogleApiClient,
context.getString(R.string.leaderboard_total_high_score)),1);
startActivityForResult(Games.Leaderboards.getLeaderboardIntent(mGoogleApiClient,
context.getString(R.string.leaderboard_grab_a_word_count)), 1);
} else {
// make dialog asking to sign in
}
}
Ok, I guess if I spent more time researching for an answer I'd saved myself time asking the question. I have made the changes to the code below. and it works great.
private static final int RC_UNUSED = 5001;
private void signToLeaderBoard() {
if (mGoogleApiClient.isConnected()) {
startActivityForResult(Games.Leaderboards.getAllLeaderboardsIntent(mGoogleApiClient),
RC_UNUSED);
// startActivityForResult(Games.Leaderboards.getLeaderboardIntent(mGoogleApiClient,
// context.getString(R.string.leaderboard_game_high_score)), 1);
} else {
// make dialog asking to sign in
}
}

how to make an android app expire after a fixed amount of time?

Hi I want that the application that I have developed to stop working after like 5 days. In short I want to time bomb my android app Can someone tell me how to do this programmatically in android studio? Any possible codes to suit this?
Thanks..
Use the following method to get the timestamp of the moment, when the app was installed for the first time:
private static long getFirstInstallTime(Context context) throws
PackageManager.NameNotFoundException {
PackageManager pm = context.getPackageManager();
PackageInfo info = pm.getPackageInfo(context.getPackageName(), 0);
return info.firstInstallTime;
}
Now you can calculate the elapsed time and compare it with your desired app lifetime:
long now = System.currentTimeMillis();
if (now - getFirstInstallTime(getApplicationContext()) >
TimeUnit.DAYS.toMillis(5)) {
sendPoisonPill();
}
Note: sendPoisonPill method is your implementation of 'time bomb'
Well,
if you know the time of publications then you can do something (silly) as
class MainActivity extends Activity {
public static final long DESTROY_APP_TH = 432000000;
#Override
protected void onCreate(Bundle savedInstanceState){
PackageManager pm = context.getPackageManager();
PackageInfo pi= pm.getPackageInfo(context.getPackageName(), 0);
long publishTimeInMilli = pi.firstInstallTime;
long now = System.currentTimeMillis();
if(now - publishTimeInMilli) > DESTROY_APP_TH) {
//just finish the the activity (and thus the app) or do something else
finish();
}
}
I am using this code to expire trial version after 26th March.
String currentTime = new SimpleDateFormat("yyyyMMdd").format(Calendar.getInstance().getTime());
Log.d("timeStamp", currentTime);
Calendar date = new GregorianCalendar(2016, Calendar.MARCH, 26);
date.add(Calendar.DAY_OF_WEEK, 0);
String expireTime = new SimpleDateFormat("yyyyMMdd").format(date.getTime());
int intcurrentTime = Integer.parseInt(currentTime);
int intexpireTime = Integer.parseInt(expireTime);
if(intcurrentTime == intexpireTime || intcurrentTime > intcurrentTime ) {
//logic to set off the features of app
tvJ2.setText("Trial period expired!!");
}
You can use AlarmManager to send an intent to your app at the specified time. Have that intent handler close your app.
Please bear in mind, however, that depending on what exactly you want to do, this is, likely, not a good thing. An Android app running (i.e. - has a process that gets scheduled by the kernel), open (i.e. - has a view that the user can change to) or active (i.e. - it is the foreground view) are almost independent states. You need to specify which is what you want to expire.
You could create app with subscription, such that after 5 days subscription expires and app becomes useless (can't be started)
In my implementation, I will add 1 variable to SharedPreference.
for example firstRun timestamp. Each time the app launch, I will get that variable and check it with the current time of the app. It is longer than 5 days (your setting), so terminate the app. But this way can't help if users change system time in their device.
The safer way is you should send this variable firstRun to your server. And each launching time, the app will request server and check condition inside your server.
Hope it helps!
I don't understand why do you want to do that, but anyway, you could create a String with a date and save it to SharedPreferences. In your main activity, before doing anything you compare the actual date with the date that you have saved in SharedPreferences (the saved date could be the first time that the application was opened or a prefixed date) and if the actual date is 5 days or more after your saved date, you can display a blank activity or whatever you want.
I have erite for you a code, where the first time you open the app the system saves the date and adds 5 days more. Then every time you open again the app you compare the saved date with the actual date, and if the actual date is after your saved date (it means that it has passed 5 days) you do whatever you want
class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState){
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
if (!prefs.getBoolean("firstRun", true) {
SharedPreferences.Editor editor = prefs.edit();
Calendar c = Calendar.getInstance();
c.setTime(new Date());
c.add(Calendar.DATE, 5); // number of days to add
String date = sdf.format(c.getTime()); // dt is now the new date
editor.putBoolean("firstRun", true);
editor.putString("valid_until", date).apply();
}
else if(new Date().after(sdf.parse(prefs.getString("valid_until","")))) {
//Show whatever you want. Or finish the activity calling to finish();
}
}

How to use datetime in android?

I have android app as I call html files one of these files page for play sound as user can
manage when the sound play as:
Saturday on
Sunday off
Monday on
and so on. I did my code well, but when I manage select input
option values to on and off it return back to its default when I close
the app or go to another page. So the question is how can keep with
select options values for first time as user selected? Also, if I want
to play sound in specific time as:
Saturday on
5.30am how can I do it?
<play sound method>
public class WebAppInterface {
Context mContext;
public MediaPlayer mp = null;
public static boolean checked = false;
/** Instantiate the interface and set the context */
WebAppInterface(Context c) {
mContext = c;
mp = MediaPlayer.create(mContext,R.raw.sound);
}
#JavascriptInterface
public void playsound(String value ) {
if (value.equals("on")){
checked = true;
mp.setLooping(true);
mp.start();
}
else
{
checked = false;
mp.stop();
}
}
}
HTML code:
<html>
<form >
<select name="flip-1" id="flip-1" data-role="slider" onchange="getAzan(this)" >
<option value="off" >play</option>
<option value="on">off</option>
</select>
</form>
<script type="text/javascript">
function getAzan(sel) {
var value = sel.options[sel.selectedIndex].value;
Android.playsound(value);
}
</script>
Note: I did play sound when user select on value at the code up
I'd say it would be better to save those things into SharedPrefences instead of storing it on a file.
To use SharedPreferences it's pretty simple. When you get the value (i.e.: on or off), just open the SharedPreferences, and put those values in it.
private void editPlayMonday(boolean shouldIPlay) {
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
prefs.edit().putBoolean("PlayMonday", shouldIPlay).commit();
}
Once your values are in place, if you want to know if you have to play a song, just check the SharedPreferences, and look what's in it that way:
private void playSong() {
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
boolean shouldIPlay = prefs.getBoolean("PlayMonday", false);//false being the default value
if(shouldIPlay) {
//play song or whatever
}
}
Now, you can have a boolean in your preferences for each days, and just check if these values or on or off for today's date.
I hope it helps!
EDIT:
So, up there I gave you the keys to manage your player, and when the sound needs to be played. The editPlayMonday function let you register on your application when you need to play your sound, and playSong lets you check the preferences to know if you have to play your song.
Now, in your application, you need to use those functions and link them to the javascript. I'll let you do it, I'm pretty sure there is a lot of tutorials and help about that (i.e.: http://developer.android.com/guide/webapps/webview.html)
The part that I didn't give the details //play song or whatever, in the playSong functions would be a bit more trickier and you should detail a bit more what you want to do with it. What I would advise you to do is to check out the AlarmManager class. It lets you schedule events from your app easily. See the doc for more information or this tutorial on how to implement it.
So to summarize, what you need to do with your application:
Link your HTML switch to the Android editPlay... function so that you can register when you need to play a song.
When you open your webview, check if the SharedPreference corresponding to each days is true or false. This way you can modify the different HTML switch to be on "on" or "off".
In the editPlay... function, and using the AlarmManager, you should schedule an alarm for the next day scheduled, which will link to your song. Remember to check in the SharedPreference if the boolean for the given day is still true. You don't want to play a song the wrong day...
Why don't you keep these values in a database? Or if it's only a few settings you want to remember then just save a file locally and read from it upon starting the application every time.
With regards to your timing question, I think this post should help you Binding MediaPlayer to be played at a specific time .
EDIT
PrintWriter writer = new PrintWriter("nameTheFile.txt", "UTF-8");
writer.println(name);
writer.println(value);
writer.close();
Should write in the file.
Read using:
String name;
Boolean value;
BufferedReader reader = new BufferedReader(new FileReader("/path/to/file.txt"));
String line = null;
while ((line = reader.readLine()) != null) {
name=line;
value=Boolean.Parse(line);
}
As described by #MagicMicky you can use SharedPreferences to store the values in onPause() method
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
prefs.edit().putBoolean("Monday", true).commit();
and then retrieve the values in onResume().
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
boolean check_monday=prefs.getBoolean("Monday",false); //false being default value
Now your data will be saved even if a user exits the app or move to new activity. As far as Alarm is concerned use AlarmManager different example here to schedule an alarm by checking SharedPreferences for any need for alarm i.e schedule alarm if check_monday==true.

Creating an Android trial application that expires after a fixed time period

I have an application which I want to hit the market as a Paid app. I would like to have other version which would be a "trial" version with a time limit of say, 5 days?
How can I go about doing this?
Currently most developers accomplish this using one of the following 3 techniques.
The first approach is easily circumvented, the first time you run the app save the date/time to a file, database, or shared preferences and every time you run the app after that check to see if the trial period has ended. This is easy to circumvent because uninstalling and reinstalling will allow the user to have another trial period.
The second approach is harder to circumvent, but still circumventable. Use a hard coded time bomb. Basically with this approach you will be hard code an end date for the trial, and all users that download and use the app will stop being able to use the app at the same time. I have used this approach because it is easy to implement and for the most part I just didn't feel like going through the trouble of the third technique. Users can circumvent this by manually changing the date on their phone, but most users won't go through the trouble to do such a thing.
The third technique is the only way that I have heard about to truly be able to accomplish what you want to do. You will have to set up a server, and then whenever your application is started your app sends the phones unique identifier to the server. If the server does not have an entry for that phone id then it makes a new one and notes the time. If the server does have an entry for the phone id then it does a simple check to see if the trial period has expired. It then communicates the results of the trial expiration check back to your application. This approach should not be circumventable, but does require setting up a webserver and such.
It is always good practice to do these checks in the onCreate. If the expiration has ended popup an AlertDialog with a market link to the full version of the app. Only include an "OK" button, and once the user clicks on "OK" make a call to "finish()" to end the activity.
I've developed a Android Trial SDK which you can simply drop into your Android Studio project and it will take care of all the server-side management for you (including offline grace periods).
To use it, simply
Add the library to your main module's build.gradle
dependencies {
compile 'io.trialy.library:trialy:1.0.2'
}
Initialize the library in your main activity's onCreate() method
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//Initialize the library and check the current trial status on every launch
Trialy mTrialy = new Trialy(mContext, "YOUR_TRIALY_APP_KEY");
mTrialy.checkTrial(TRIALY_SKU, mTrialyCallback);
}
Add a callback handler:
private TrialyCallback mTrialyCallback = new TrialyCallback() {
#Override
public void onResult(int status, long timeRemaining, String sku) {
switch (status){
case STATUS_TRIAL_JUST_STARTED:
//The trial has just started - enable the premium features for the user
break;
case STATUS_TRIAL_RUNNING:
//The trial is currently running - enable the premium features for the user
break;
case STATUS_TRIAL_JUST_ENDED:
//The trial has just ended - block access to the premium features
break;
case STATUS_TRIAL_NOT_YET_STARTED:
//The user hasn't requested a trial yet - no need to do anything
break;
case STATUS_TRIAL_OVER:
//The trial is over
break;
}
Log.i("TRIALY", "Trialy response: " + Trialy.getStatusMessage(status));
}
};
To start a trial, call mTrialy.startTrial("YOUR_TRIAL_SKU", mTrialyCallback);
Your app key and trial SKU can be found in your Trialy developer dashboard.
This is an old question but anyways, maybe this will help someone.
In case you want to go with the most simplistic approach(which will fail if the app is uninstalled/reinstalled or user changes device's date manually), this is how it could be:
private final SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");
private final long ONE_DAY = 24 * 60 * 60 * 1000;
#Override
protected void onCreate(Bundle state){
SharedPreferences preferences = getPreferences(MODE_PRIVATE);
String installDate = preferences.getString("InstallDate", null);
if(installDate == null) {
// First run, so save the current date
SharedPreferences.Editor editor = preferences.edit();
Date now = new Date();
String dateString = formatter.format(now);
editor.putString("InstallDate", dateString);
// Commit the edits!
editor.commit();
}
else {
// This is not the 1st run, check install date
Date before = (Date)formatter.parse(installDate);
Date now = new Date();
long diff = now.getTime() - before.getTime();
long days = diff / ONE_DAY;
if(days > 30) { // More than 30 days?
// Expired !!!
}
}
...
}
This question and the answer of snctln inspired me to work on a solution based on method 3 as my bachelor thesis. I know the current status is not for productive usage but I would love to hear what you think about it! Would you use such a system? Would you like to see it as a cloud service (not having trouble with configuring a server)? Concerned about security issues or stability reasons?
A soon as I finished the bachelor procedure I want to continue working on the software. So now its the time I need your feedback!
Sourcecode is hosted on GitHub https://github.com/MaChristmann/mobile-trial
Some information about the system:
- The system has three parts, a Android library, a node.js server and a configurator for managing multiple trial apps and publisher/developer accounts.
It only supports time-based trials and it uses your (play store or other) account rather than a phone ID.
For Android library it is based on the Google Play licensing verification library. I modified it to connect to the node.js server and additionally the library tries to recognize if a user changed the system date. It also caches a retrieved trial-license in AES encrypted Shared Preferences. You can configure the valid time of the cache with the configurator. If a user "clear data" the library will force a server-side check.
Server is using https and also digital signing the license-check response. It has also an API for CRUD trial apps and users (publisher and developer). Similiar to Licensing Verfication Library developers can test their behaviour implementation in the trial app with test result. So you in the configurator you can explicit set your license response to "licensed", "not licensed" or "server error".
If you update your app with an ass-kicking new feature you might want that everyone can try it again. In the configurator you can renew the trial license for users with expired licenses by setting a versioncode that should trigger this. For example user is running your app on versioncode 3 und you want him to try features of versioncode 4. If he updates the app or reinstall it he is able to use full trial period again because the server knows on which version he has tried it last time.
Everything is under the Apache 2.0 license
The easiest and best way to do this is the implement BackupSharedPreferences.
The preferences are preserved, even if the app is uninstalled and reinstalled.
Simply save the install date as a preference and you are good to go.
Here's the theory:
http://developer.android.com/reference/android/app/backup/SharedPreferencesBackupHelper.html
Here's the example:
Android SharedPreferences Backup Not Working
Approach 4: use the application install time.
Since API level 9 (Android 2.3.2, 2.3.1, Android 2.3, GINGERBREAD) there are firstInstallTime and lastUpdateTime in PackageInfo.
To read more:
How to get app install time from android
After looking at all options in this and other threads, these are my findings
Shared preferences, database
Can be cleared in the android settings, lost after an app reinstall. Can be backed up with android's backup mechanism and will be restored after a reinstall. Backup may not always be available, though should be on most devices
External storage (writing to a file)
Not affected by a clear from the settings or a reinstall if we don't write to the application's private directory. But: requires you to ask the user for their permission at runtime in newer android versions, so this is probably only feasible if you need that permission anyways. Can also be backed up.
PackageInfo.firstInstallTime
Is reset after a reinstall but stable across updates
Sign in to some account
Doesn't matter if it's their Google account via Firebase or one in your own server: the trial is bound to the account. Making a new account will reset the trial.
Firebase anonymous sign in
You can sign in a user anonymously and store data for them in Firebase. But apparently a reinstall of the app and maybe other undocumented events may give the user a new anonymous ID, resetting their trial time. (Google themselves don't provide much documentation on this)
ANDROID_ID
May not be available and may change under certain circumstances, e.g factory reset. The opinions on whether it's a good idea to use this to identify devices seem to differ.
Play Advertising ID
May be reset by the user. May be disabled by the user by opting out of ad tracking.
InstanceID
Reset on a reinstall. Reset in case of a security event. Can be reset by your app.
Which (combination of) methods work for you depends on your app and on how much effort you think the average John will put into gaining another trial period. I would recommend steering clear of using only anonymous Firebase and Advertising ID due to their instability. A multi-factor approach seems like it will yield the best results. Which factors are available to you depends on you app and its permissions.
For my own app I found shared preferences + firstInstallTime + backup of the preferences to be the least intrusive but also effective enough method. You have to make sure you only request a backup after checking and storing the trial start time in the shared preferences. Values in the shared Prefs must have precedence over the firstInstallTime. Then user has to reinstall the app, run it once and then clear the app's data to reset the trial, which is quite a lot of work. On devices without a backup transport the user can reset the trial by simply reinstalling, though.
I've made that approach available as an extensible library.
Now in the recent version of android free trial subscription has been added, you can unlock all your app's features only after buying the subscription within app for a free trial period.
This will let the user to use your app for a trial period , if the app is still uninstalled after the trial period then the subscription money will be transferred to you.
I have not tried , but just sharing an idea.
Here's documentation
In my opinion, the best way to do this is to simply use the Firebase Realtime Database:
1) Add Firebase support to your app
2) Select 'Anonymous authentication' so that the user doesn't have to signup or even know what you're doing. This is guaranteed to link to the currently authenticated user account and so will work across devices.
3) Use the Realtime Database API to set a value for 'installed_date'. At launch time, simply retrieve this value and use this.
I've done the same and it works great. I was able to test this across uninstall / re-installs and the value in the realtime database remains the same. This way your trial period works across multiple user devices. You can even version your install_date so that the app 'resets' the Trial date for each new major release.
UPDATE: After testing a bit more, it seems anonymous Firebase seems to allocate a different ID in case you've got different devices and is not guaranteed between re-installs :/ The only guaranteed way is to use Firebase but tie it to their google account. This should work, but would require an extra step where the user first needs to login / signup.
I've thus far ended up with a slightly less elegant approach of simply checking against backed-up preferences and a date stored in preferences upon install. This works for data-centric apps where it's pointless for a person to re-install the app and re-enter all the data previously added, but would not work for a simple game.
By definition, all paid Android apps on the market can be evaluated for 24 hours after purchase.
There's an 'Uninstall and Refund' button which changes to 'Uninstall' after 24 hours.
I'd argue this button is way too prominent!
I come across this question while searching for the same problem, i think we can utilize free date api like http://www.timeapi.org/utc/now or some other date api to check for expiry of trail app. this way is efficient if you wish to deliver the demo and worried about payment and require fix tenure demo. :)
find the code below
public class ValidationActivity extends BaseMainActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
#Override
protected void onResume() {
processCurrentTime();
super.onResume();
}
private void processCurrentTime() {
if (!isDataConnectionAvailable(ValidationActivity.this)) {
showerrorDialog("No Network coverage!");
} else {
String urlString = "http://api.timezonedb.com/?zone=Europe/London&key=OY8PYBIG2IM9";
new CallAPI().execute(urlString);
}
}
private void showerrorDialog(String data) {
Dialog d = new Dialog(ValidationActivity.this);
d.setTitle("LS14");
TextView tv = new TextView(ValidationActivity.this);
tv.setText(data);
tv.setPadding(20, 30, 20, 50);
d.setContentView(tv);
d.setOnDismissListener(new OnDismissListener() {
#Override
public void onDismiss(DialogInterface dialog) {
finish();
}
});
d.show();
}
private void checkExpiry(int isError, long timestampinMillies) {
long base_date = 1392878740000l;// feb_19 13:8 in GMT;
// long expiryInMillies=1000*60*60*24*5;
long expiryInMillies = 1000 * 60 * 10;
if (isError == 1) {
showerrorDialog("Server error, please try again after few seconds");
} else {
System.out.println("fetched time " + timestampinMillies);
System.out.println("system time -" + (base_date + expiryInMillies));
if (timestampinMillies > (base_date + expiryInMillies)) {
showerrorDialog("Demo version expired please contact vendor support");
System.out.println("expired");
}
}
}
private class CallAPI extends AsyncTask<String, String, String> {
#Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
}
#Override
protected String doInBackground(String... params) {
String urlString = params[0]; // URL to call
String resultToDisplay = "";
InputStream in = null;
// HTTP Get
try {
URL url = new URL(urlString);
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
in = new BufferedInputStream(urlConnection.getInputStream());
resultToDisplay = convertStreamToString(in);
} catch (Exception e) {
System.out.println(e.getMessage());
return e.getMessage();
}
return resultToDisplay;
}
protected void onPostExecute(String result) {
int isError = 1;
long timestamp = 0;
if (result == null || result.length() == 0 || result.indexOf("<timestamp>") == -1 || result.indexOf("</timestamp>") == -1) {
System.out.println("Error $$$$$$$$$");
} else {
String strTime = result.substring(result.indexOf("<timestamp>") + 11, result.indexOf("</timestamp>"));
System.out.println(strTime);
try {
timestamp = Long.parseLong(strTime) * 1000;
isError = 0;
} catch (NumberFormatException ne) {
}
}
checkExpiry(isError, timestamp);
}
} // end CallAPI
public static boolean isDataConnectionAvailable(Context context) {
ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo info = connectivityManager.getActiveNetworkInfo();
if (info == null)
return false;
return connectivityManager.getActiveNetworkInfo().isConnected();
}
public String convertStreamToString(InputStream is) throws IOException {
if (is != null) {
Writer writer = new StringWriter();
char[] buffer = new char[1024];
try {
Reader reader = new BufferedReader(new InputStreamReader(is, "UTF-8"));
int n;
while ((n = reader.read(buffer)) != -1) {
writer.write(buffer, 0, n);
}
} finally {
is.close();
}
return writer.toString();
} else {
return "";
}
}
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
}
}
its working solution.....
Here is how i went about mine,
I created 2 apps one with trial activity the other without,
i uploaded the one without trial activity to play store as paid app,
and the one with trial activity as free app.
The free app on first launch has options for trial and store purchase,
if the user select store purchase it redirects to the store for the user to purchase
but if the user clicks trial it take them to the trial activity
NB: I used option 3 like #snctln but with modifications
first, i did not depend on the device time, i got my time from the php file that does the trial registration to the db,
secondly, i used the device serial number to uniquely identify each device,
lastly, the app depends on the time value returned from the server connection not its own time so the system can only be circumvented if the device serial number is changed, which is quite stressful for a user.
so here goes my code (for the Trial activity):
package com.example.mypackage.my_app.Start_Activity.activity;
import android.Manifest;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.pm.PackageManager;
import android.graphics.Color;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.telephony.TelephonyManager;
import android.view.KeyEvent;
import android.widget.TextView;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonObjectRequest;
import com.android.volley.toolbox.Volley;
import com.example.onlinewisdom.cbn_app.R;
import com.example.mypackage.my_app.Start_Activity.app.Config;
import com.example.mypackage.my_app.Start_Activity.data.TrialData;
import com.example.mypackage.my_app.Start_Activity.helper.connection.Connection;
import com.google.gson.Gson;
import org.json.JSONObject;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import cn.pedant.SweetAlert.SweetAlertDialog;
public class Trial extends AppCompatActivity {
Connection check;
SweetAlertDialog pDialog;
TextView tvPleaseWait;
private static final int MY_PERMISSIONS_REQUEST_READ_PHONE_STATE = 0;
String BASE_URL = Config.BASE_URL;
String BASE_URL2 = BASE_URL+ "/register_trial/"; //http://ur link to ur API
//KEY
public static final String KEY_IMEI = "IMEINumber";
private final SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");
private final long ONE_DAY = 24 * 60 * 60 * 1000;
SharedPreferences preferences;
String installDate;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_trial);
preferences = getPreferences(MODE_PRIVATE);
installDate = preferences.getString("InstallDate", null);
pDialog = new SweetAlertDialog(this, SweetAlertDialog.PROGRESS_TYPE);
pDialog.getProgressHelper().setBarColor(Color.parseColor("#008753"));
pDialog.setTitleText("Loading...");
pDialog.setCancelable(false);
tvPleaseWait = (TextView) findViewById(R.id.tvPleaseWait);
tvPleaseWait.setText("");
if(installDate == null) {
//register app for trial
animateLoader(true);
CheckConnection();
} else {
//go to main activity and verify there if trial period is over
Intent i = new Intent(Trial.this, MainActivity.class);
startActivity(i);
// close this activity
finish();
}
}
public void CheckConnection() {
check = new Connection(this);
if (check.isConnected()) {
//trigger 'loadIMEI'
loadIMEI();
} else {
errorAlert("Check Connection", "Network is not detected");
tvPleaseWait.setText("Network is not detected");
animateLoader(false);
}
}
public boolean onKeyDown(int keyCode, KeyEvent event) {
//Changes 'back' button action
if (keyCode == KeyEvent.KEYCODE_BACK) {
finish();
}
return true;
}
public void animateLoader(boolean visibility) {
if (visibility)
pDialog.show();
else
pDialog.hide();
}
public void errorAlert(String title, String msg) {
new SweetAlertDialog(this, SweetAlertDialog.ERROR_TYPE)
.setTitleText(title)
.setContentText(msg)
.show();
}
/**
* Called when the 'loadIMEI' function is triggered.
*/
public void loadIMEI() {
// Check if the READ_PHONE_STATE permission is already available.
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_PHONE_STATE)
!= PackageManager.PERMISSION_GRANTED) {
// READ_PHONE_STATE permission has not been granted.
requestReadPhoneStatePermission();
} else {
// READ_PHONE_STATE permission is already been granted.
doPermissionGrantedStuffs();
}
}
/**
* Requests the READ_PHONE_STATE permission.
* If the permission has been denied previously, a dialog will prompt the user to grant the
* permission, otherwise it is requested directly.
*/
private void requestReadPhoneStatePermission() {
if (ActivityCompat.shouldShowRequestPermissionRationale(this,
Manifest.permission.READ_PHONE_STATE)) {
// Provide an additional rationale to the user if the permission was not granted
// and the user would benefit from additional context for the use of the permission.
// For example if the user has previously denied the permission.
new AlertDialog.Builder(Trial.this)
.setTitle("Permission Request")
.setMessage(getString(R.string.permission_read_phone_state_rationale))
.setCancelable(false)
.setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
//re-request
ActivityCompat.requestPermissions(Trial.this,
new String[]{Manifest.permission.READ_PHONE_STATE},
MY_PERMISSIONS_REQUEST_READ_PHONE_STATE);
}
})
.setIcon(R.drawable.warning_sigh)
.show();
} else {
// READ_PHONE_STATE permission has not been granted yet. Request it directly.
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_PHONE_STATE},
MY_PERMISSIONS_REQUEST_READ_PHONE_STATE);
}
}
/**
* Callback received when a permissions request has been completed.
*/
#Override
public void onRequestPermissionsResult(int requestCode, #NonNull String[] permissions, #NonNull int[] grantResults) {
if (requestCode == MY_PERMISSIONS_REQUEST_READ_PHONE_STATE) {
// Received permission result for READ_PHONE_STATE permission.est.");
// Check if the only required permission has been granted
if (grantResults.length == 1 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
// READ_PHONE_STATE permission has been granted, proceed with displaying IMEI Number
//alertAlert(getString(R.string.permision_available_read_phone_state));
doPermissionGrantedStuffs();
} else {
alertAlert(getString(R.string.permissions_not_granted_read_phone_state));
}
}
}
private void alertAlert(String msg) {
new AlertDialog.Builder(Trial.this)
.setTitle("Permission Request")
.setMessage(msg)
.setCancelable(false)
.setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
// do somthing here
}
})
.setIcon(R.drawable.warning_sigh)
.show();
}
private void successAlert(String msg) {
new SweetAlertDialog(this, SweetAlertDialog.SUCCESS_TYPE)
.setTitleText("Success")
.setContentText(msg)
.setConfirmText("Ok")
.setConfirmClickListener(new SweetAlertDialog.OnSweetClickListener() {
#Override
public void onClick(SweetAlertDialog sDialog) {
sDialog.dismissWithAnimation();
// Prepare intent which is to be triggered
//Intent i = new Intent(Trial.this, MainActivity.class);
//startActivity(i);
}
})
.show();
}
public void doPermissionGrantedStuffs() {
//Have an object of TelephonyManager
TelephonyManager tm =(TelephonyManager)getSystemService(Context.TELEPHONY_SERVICE);
//Get IMEI Number of Phone //////////////// for this example i only need the IMEI
String IMEINumber = tm.getDeviceId();
/************************************************
* **********************************************
* This is just an icing on the cake
* the following are other children of TELEPHONY_SERVICE
*
//Get Subscriber ID
String subscriberID=tm.getDeviceId();
//Get SIM Serial Number
String SIMSerialNumber=tm.getSimSerialNumber();
//Get Network Country ISO Code
String networkCountryISO=tm.getNetworkCountryIso();
//Get SIM Country ISO Code
String SIMCountryISO=tm.getSimCountryIso();
//Get the device software version
String softwareVersion=tm.getDeviceSoftwareVersion()
//Get the Voice mail number
String voiceMailNumber=tm.getVoiceMailNumber();
//Get the Phone Type CDMA/GSM/NONE
int phoneType=tm.getPhoneType();
switch (phoneType)
{
case (TelephonyManager.PHONE_TYPE_CDMA):
// your code
break;
case (TelephonyManager.PHONE_TYPE_GSM)
// your code
break;
case (TelephonyManager.PHONE_TYPE_NONE):
// your code
break;
}
//Find whether the Phone is in Roaming, returns true if in roaming
boolean isRoaming=tm.isNetworkRoaming();
if(isRoaming)
phoneDetails+="\nIs In Roaming : "+"YES";
else
phoneDetails+="\nIs In Roaming : "+"NO";
//Get the SIM state
int SIMState=tm.getSimState();
switch(SIMState)
{
case TelephonyManager.SIM_STATE_ABSENT :
// your code
break;
case TelephonyManager.SIM_STATE_NETWORK_LOCKED :
// your code
break;
case TelephonyManager.SIM_STATE_PIN_REQUIRED :
// your code
break;
case TelephonyManager.SIM_STATE_PUK_REQUIRED :
// your code
break;
case TelephonyManager.SIM_STATE_READY :
// your code
break;
case TelephonyManager.SIM_STATE_UNKNOWN :
// your code
break;
}
*/
// Now read the desired content to a textview.
//tvPleaseWait.setText(IMEINumber);
UserTrialRegistrationTask(IMEINumber);
}
/**
* Represents an asynchronous login task used to authenticate
* the user.
*/
private void UserTrialRegistrationTask(final String IMEINumber) {
JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.GET, BASE_URL2+IMEINumber, null,
new Response.Listener<JSONObject>() {
#Override
public void onResponse(JSONObject response) {
Gson gson = new Gson();
TrialData result = gson.fromJson(String.valueOf(response), TrialData.class);
animateLoader(false);
if ("true".equals(result.getError())) {
errorAlert("Error", result.getResult());
tvPleaseWait.setText("Unknown Error");
} else if ("false".equals(result.getError())) {
//already created install/trial_start date using the server
// so just getting the date called back
Date before = null;
try {
before = (Date)formatter.parse(result.getResult());
} catch (ParseException e) {
e.printStackTrace();
}
Date now = new Date();
assert before != null;
long diff = now.getTime() - before.getTime();
long days = diff / ONE_DAY;
// save the date received
SharedPreferences.Editor editor = preferences.edit();
editor.putString("InstallDate", String.valueOf(days));
// Commit the edits!
editor.apply();
//go to main activity and verify there if trial period is over
Intent i = new Intent(Trial.this, MainActivity.class);
startActivity(i);
// close this activity
finish();
//successAlert(String.valueOf(days));
//if(days > 5) { // More than 5 days?
// Expired !!!
//}
}
}
},
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
animateLoader(false);
//errorAlert(error.toString());
errorAlert("Check Connection", "Could not establish a network connection.");
tvPleaseWait.setText("Network is not detected");
}
})
{
protected Map<String, String> getParams() {
Map<String, String> params = new HashMap<String, String>();
params.put(KEY_IMEI, IMEINumber);
return params;
}
};
RequestQueue requestQueue = Volley.newRequestQueue(this);
requestQueue.add(jsonObjectRequest);
}
}
My php file looks like this (its a REST-slim technology):
/**
* registerTrial
*/
public function registerTrial($IMEINumber) {
//check if $IMEINumber already exist
// Instantiate DBH
$DBH = new PDO_Wrapper();
$DBH->query("SELECT date_reg FROM trials WHERE device_id = :IMEINumber");
$DBH->bind(':IMEINumber', $IMEINumber);
// DETERMINE HOW MANY ROWS OF RESULTS WE GOT
$totalRows_registered = $DBH->rowCount();
// DETERMINE HOW MANY ROWS OF RESULTS WE GOT
$results = $DBH->resultset();
if (!$IMEINumber) {
return 'Device serial number could not be determined.';
} else if ($totalRows_registered > 0) {
$results = $results[0];
$results = $results['date_reg'];
return $results;
} else {
// Instantiate variables
$trial_unique_id = es_generate_guid(60);
$time_reg = date('H:i:s');
$date_reg = date('Y-m-d');
$DBH->beginTransaction();
// opening db connection
//NOW Insert INTO DB
$DBH->query("INSERT INTO trials (time_reg, date_reg, date_time, device_id, trial_unique_id) VALUES (:time_reg, :date_reg, NOW(), :device_id, :trial_unique_id)");
$arrayValue = array(':time_reg' => $time_reg, ':date_reg' => $date_reg, ':device_id' => $IMEINumber, ':trial_unique_id' => $trial_unique_id);
$DBH->bindArray($arrayValue);
$subscribe = $DBH->execute();
$DBH->endTransaction();
return $date_reg;
}
}
then on the main activity i use the shared preference (installDate created in trial activity) to monitor the number of days remaining and if the days are over i block the main activity UI with a message that takes them to the store to purchase.
The only down side i see here is that if a Rogue user buys the paid app and decides to share with apps like Zender, file share or even host the apk file directly on a server for people to download for free. But am sure i will soon edit this answer with a solution to that or a link to the solution.
Hope this saves a soul...some day
Happy Coding...
#snctln option 3 can be easily done adding a php file to a web server with php and mysql installed as many of them have.
From the Android side an identifier (the device ID, google account o whatever you want) is passed as argument in the URL using HttpURLConnection and the php returns the date of the first install if it exist in the table or it inserts a new row and it return the current date.
It works fine for me.
If I have time I will post some code !
Good Luck !

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