Develop Reference

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

Verify if user is logged in or not, issues using Intent in Android

I am attempting to verify if a user is logged in or not, and if not sending them to a log in page. I am using the log in page template from Android Dev. and trying to use an Intent to send either a Boolean or a value ( 1 for logged in 0 for not). Here is the part of the code in LoginActivity with the Intent:
for (String credential : DUMMY_CREDENTIALS) {
String[] pieces = credential.split(":");
if (pieces[0].equals(mEmail)) {
// Account exists, return true if the password matches.
return pieces[1].equals(mPassword);
final boolean logged_in = true;
Intent intent = new Intent(LoginActivity.this, MainActivity.class);
intent.putExtra("log", logged_in);
startActivity(intent);
}
here I am trying as a Boolean and I am getting the error Unreachable code for the line with final boolean Logged_in = true. When I try as an int
int logged_in =1;
I get the same error. All the questions asked on SO state that I needed to use the current class, LoginActivity.this, instead of just this. When I did use just this, I got another error entirely.
How do I send a value to my MainActivity class to show whether they are logged in or not?

return pieces[1].equals(mPassword);
return ends the method routine so everything after is not reachable.

Trying to get an Android jabber app to check for a string in new messages and return a toast message

I have been able to create the if statement that checks for the string and it returns the toast message that i created but it keeps showing the toast message every time i open the chat. even if the most recent message doesn't contain the string I am looking for so i am assume it isn't checking to see if it is the last message received and it doesn't check to see if it is unread. the code is below. the reason i am trying to do this is because my parents share a facebook account and i want an easy way to display if the message is signed mom or dad. the code below only has the check for mom once it works i will be adding the check for dad signature. I am using the open source message client Xabber. Thank you for help.
public void setVisibleChat(String account, String user) {
final boolean remove = !AccountManager.getInstance()
.getArchiveMode(account).saveLocally();
AbstractChat chat = getChat(account, user);
if (chat == null)
chat = createChat(account, user);
else {
// Mark messages as read and them delete from db if necessary.
final ArrayList<MessageItem> messageItems = new ArrayList<MessageItem>();
for (MessageItem messageItem : chat.getMessages()) {
if (!messageItem.isRead()) {
messageItem.markAsRead();
messageItems.add(messageItem);
}
if (chat.getLastText().contains("Mom") && (!messageItem.isRead()));{
Toast.makeText(Application.getInstance(), "Message from Mom!", Toast.LENGTH_SHORT).show();
}
}
Application.getInstance().runInBackground(new Runnable() {
#Override
public void run() {
Collection<Long> ids = getMessageIds(messageItems, remove);
if (remove)
MessageTable.getInstance().removeMessages(ids);
else
MessageTable.getInstance().markAsRead(ids);
}
});
}
visibleChat = chat;
}

You've got an extra semi-colon here
if (chat.getLastText().contains("Mom") && (!messageItem.isRead())); <------
So your next block of code containing the Toast show statement will always be executed.
Remove the semi-colon

Can not get Registration ID in Emulator

Hi I am running ADMMessenger sample application provided with SDK.
in which I am not able to get Registration ID in register() method of MainActivity.
Method is like this.
private void register()
{
final ADM adm = new ADM(this);
if (adm.isSupported())
{
if(adm.getRegistrationId() == null)
{
adm.startRegister();
} else {
// final MyServerMsgHandler srv = new MyServerMsgHandler();
// srv.registerAppInstance(getApplicationContext(), adm.getRegistrationId());
}
Log.v("log_tag","Reg_id:: "+adm.getRegistrationId());
}
}
in Log cat I am always getting Reg_id:: null
and onRegistrationError() method of SampleADMMessageHandler is calling.
and error at there is ERROR_SERVICE_NOT_AVAILABLE
I can not understand what is problem, please help me.

For the service to work correctly you need to be using the Kindle image (not a generic Android one) and also make sure you have logged into your account on the device (pull down the status bar at the top and ensure you have selected an account)

Android billing - how to set up a buy buttons and correctly read whether the user canceled or bought?

I am working from the Dungeons example that the Android provides, and it feels like I almost got it correctly, but I can't figure out how to detect if the person pressed the back button and backed out of the purchase. Here is what I have so far:
Button buy = (Button)findViewById(R.id.buy);
buy.setOnClickListener(new Button.OnClickListener()
{
public void onClick(View v)
{
try
{
if (mBillingService.requestPurchase(issueProductId,
Consts.ITEM_TYPE_INAPP , null))
{
// Not sure what to do here. Has the person been sent to the buy screen yet or no?
// There are these strings I need to check for but not entirely certain how:
if(mBillingService.checkBillingSupported(Consts.ITEM_TYPE_INAPP))
{
// OK
}
else
{
// If billing is not supported, give them the item for free
Intent myIntent = new Intent(ExtraHelpActivity.this, PsychologyActivity.class);
ExtraHelpActivity.this.startActivity(myIntent);
}
try
{
if (mBillingService.requestPurchase(issueProductIdPsych,
Consts.ITEM_TYPE_INAPP , null))
{
// HOW DO I CHECK HERE IF THE USER CANCELED OUT OF THE PURCHASE?
// EVEN ON CANCEL, THEY ARE BEING TAKEN TO THE ITEM THAT THEY NEED TO PAY FOR.
// Send them to the screen of the article.
Intent myIntent = new Intent(ExtraHelpActivity.this, PsychologyActivity.class);
ExtraHelpActivity.this.startActivity(myIntent);
}
}
catch ( Exception e )
{
// Report exception.
}
});
I added some inline comments where I am confused. I am not certain how to read whether the person purchased the item, or cancelled. If someone could help me with this, that would be great.
Right now this code takes the person to the buy screen, and some people buy, but when people press cancel, they still get taken to the item which they didn't buy. :)
EDIT:
By the way, if users already bought the item and want to come back to it, the purchase request state does not change, right? So what method ends up being triggered? I tested with one purchase and I was able to buy access to one screen with an article, but now can not get to it again since the payment screen keeps telling me I already bought that item, and not taking me to the next page.
Here is how my new onStateChanged method looks like:
#Override
public void onPurchaseStateChange(PurchaseState purchaseState, String itemId,
int quantity, long purchaseTime, String developerPayload)
{
if (purchaseState == PurchaseState.PURCHASED)
{
mOwnedItems.add(itemId);
if ( itemId != null && itemId.trim().equals("3") )
{
Intent myIntent = new Intent(ExtraHelpActivity.this, PsychologyActivity.class);
ExtraHelpActivity.this.startActivity(myIntent);
}
if ( itemId != null && itemId.trim().equals("4") )
{
Intent myIntent = new Intent(ExtraHelpActivity.this, NumberOfBusinessesActivity.class);
}
}
else
if (purchaseState == PurchaseState.CANCELED)
{
// purchase canceled
}
else
if (purchaseState == PurchaseState.REFUNDED)
{
// user ask for a refund
}
else
{
if ( itemId != null && itemId.equals("3") )
{
Intent myIntent = new Intent(ExtraHelpActivity.this, PsychologyActivity.class);
ExtraHelpActivity.this.startActivity(myIntent);
}
if ( itemId != null && itemId.equals("4") )
{
Intent myIntent = new Intent(ExtraHelpActivity.this, NumberOfBusinessesActivity.class);
ExtraHelpActivity.this.startActivity(myIntent);
}
}
}
and when I tested it and bought an article, it did get here to the if (purchaseState == PurchaseState.PURCHASED) but not the individual if cases inside it even though the itemId id is "3" or "4"
EDIT:
and this is how I declare the product ids at the beginning of the Activity:
String issueProductIdWebMarketing = "1";
String issueProductIdDonate = "2";
String issueProductIdPsych = "3";
String issueProductIdNumberofBusinesses = "4";
Thanks!!

According to the billing integration guide:
when the requested transaction changes state (for example, the purchase is successfully charged to a credit
card or the user cancels the purchase), the Google Play application sends an IN_APP_NOTIFY broadcast intent.
This message contains a notification ID, which you can use to retrieve the transaction details for the
REQUEST_PURCHASE request.
And the intent com.android.vending.billing.PURCHASE_STATE_CHANGED contains purchaseState
The purchase state of the order. Possible values are 0 (purchased), 1 (canceled), 2 (refunded), or 3
(expired, for subscription purchases only).
source (table 4)
EDIT:
In the dungeons sample, there is an inner class extending PurchaseObserver (see Dungeons activity) that does the job, see especially (onPurchaseStateChange)
EDIT2: some pseudo-code
in the activity (Dungeons class in the sdk sample):
Button buy = (Button)findViewById(R.id.buy);
buy.setEnabled(false);
buy.setOnClickListener(new Button.OnClickListener() {
public void onClick(View v)
{
// show purchase dialog and call mBillingService.requestPurchase() on dialog validation
}
});
// request to see if supported
if (!mBillingService.checkBillingSupported()) {
// not supported
}
in the observer (DungeonsPurchaseObserver in the sample):
public void onBillingSupported(boolean supported, String type) {
if (type == null || type.equals(Consts.ITEM_TYPE_INAPP)) {
if (supported) {
// billing supported: enable buy button
} else {
// billing not supported: disable buy button
}
}
}
public void onPurchaseStateChange(PurchaseState purchaseState, String itemId,
int quantity, long purchaseTime, String developerPayload) {
if (purchaseState == PurchaseState.PURCHASED) {
// item purchased
} else if (purchaseState == PurchaseState.CANCELED) {
// purchase canceled
} else if (purchaseState == PurchaseState.REFUND) {
// user ask for a refund
}
}

The problem is that the call mBillingService.requestPurchase is not synchronous. So you can not check right after if the purchase was successful or not.
I recommend you use the library AndroidBillingLibrary. With it you can easily get all the Google Play's events. For that you can use onRequestPurchaseResponse() and onPurchaseStateChanged() from the helpers AbstractBillingActivity or AbstractBillingFragment.