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Consumers want immediate access to what’s relevant and QR codes are being used to make that possible.

Bar codes are linear one-dimensional codes and can only hold up to 20 numerical digits, whereas QR codes are two-dimensional (2D) matrix barcodes that can hold thousands of alphanumeric characters of information. Their ability to hold more information and their ease of use makes them practical for small businesses.

When you scan or read a QR code with your iPhone, Android or other camera-enabled Smartphone, you can link to digital content on the web; activate a number of phone functions including email, IM and SMS; and connect the mobile device to a web browser.

As part of my job, I ran into memory leaks issues in Android applications and they are most of the time due to the same mistake: keeping a long-lived reference to a Context.

There are two easy ways to avoid context-related memory leaks. The most obvious one is to avoid escaping the context outside of its own scope. The example above showed the case of a static reference but inner classes and their implicit reference to the outer class can be equally dangerous. The second solution is to use the Application context. This context will live as long as your application is alive and does not depend on the activities life cycle. If you plan on keeping long-lived objects that need a context, remember the application object. You can obtain it easily by calling Context.getApplicationContext() or Activity.getApplication().

In summary, to avoid context-related memory leaks, remember the following: Do not keep long-lived references to a context-activity (a reference to an activity should have the same life cycle as the activity itself) Try using the context-application instead of a context-activity Avoid non-static inner classes in an activity if you don't control their life cycle, use a static inner class and make a weak reference to the activity inside. The solution to this issue is to use a static inner class with a WeakReference to the outer class, as done in ViewRoot and its W inner class for instance A garbage collector is not an insurance against memory leaks

It allows third-party application servers to send lightweight messages to their Android applications. The messaging service is not designed for sending a lot of user content via the messages. Rather, it should be used to tell the application that there is new data on the server, so that the application can fetch it. C2DM makes no guarantees about delivery or the order of messages. So, for example, while you might use this feature to tell an instant messaging application that the user has new messages, you probably would not use it to pass the actual messages. An application on an Android device doesn’t need to be running to receive messages. The system will wake up the application via Intent broadcast when the the message arrives, as long as the application is set up with the proper broadcast receiver and permissions.

It uses an existing connection for Google services. This requires users to set up their Google account on their mobile devices.

C2DM imposes the following limitations: The message size limit is 1024 bytes. Google limits the number of messages a sender sends in aggregate, and the number of messages a sender sends to a specific device

The Android Market engineering team has been hard at work on improving the Android Market experience for users and developers. Today, I’m pleased to announce a significant update to the Android Market client. Over the next two weeks, we’ll be rolling out a new Android Market client to all devices running Android 1.6 or higher.This new Market client introduces important features that improve merchandising of applications, streamline the browse-to-purchase experience, and make it easier for developers to distribute their applications.

To make it easier for developers to distribute and manage their products, we will introduce support for device targeting based on screen sizes and densities, as well as on GL texture compression formats. We are also increasing the maximum size for .apk files on Market to 50MB, to better support richer games.

To streamline the browse-to-purchase experience, users can now access all the information about an application on a single page without the need to navigate across different tabs.

This article describes a technique you can use to find out whether the system contains any application capable of responding to the intent you want to use. The example below shows a helper method that queries the system package manager to determine whether there's an app that can respond to a specified intent. Your application can pass an intent to the method and then, for example, show or hide user options that the user would normally use to trigger the intent.

/** * Indicates whether the specified action can be used as an intent. This * method queries the package manager for installed packages that can * respond to an intent with the specified action. If no suitable package is * found, this method returns false. * * @param context The application's environment. * @param action The Intent action to check for availability. * * @return True if an Intent with the specified action can be sent and *         responded to, false otherwise. */public static boolean isIntentAvailable(Context context, String action) {    final PackageManager packageManager = context.getPackageManager();    final Intent intent = new Intent(action);    List<ResolveInfo> list =            packageManager.queryIntentActivities(intent,                    PackageManager.MATCH_DEFAULT_ONLY);    return list.size() > 0;}

@Overridepublic boolean onPrepareOptionsMenu(Menu menu) {    final boolean scanAvailable = isIntentAvailable(this,        "com.google.zxing.client.android.SCAN");    MenuItem item;    item = menu.findItem(R.id.menu_item_add);    item.setEnabled(scanAvailable);    return super.onPrepareOptionsMenu(menu);}

An AppWidgetProvider is a BroadcastReceiver. That gives you two possibilities right off the bat: 1. Have it also handle whatever other Intents you were planning on setting up with a separate BroadcastReceiver, or 2. Send an Intent from whatever component you want to the AppWidgetProvider. In other words, don't worry about trying to talk directly to the app widget (which I suspect is impossible) -- just talk to your code that already talks to the app widget.

I update my widget from within my app, when I delete/add entries to a list. To do this, I have a method (updateWidget) and a static String (UPDATE_ACTION). My updateWidget() method sends a broadcast which is received by the widget class and then calls onUpdate() with the appropriate params: private void updateWidget() {                 Intent i = new Intent(this, TVWidget.class);                 i.setAction(TVWidget.UPDATE_ACTION);                 sendBroadcast(i);         } In TVWidget class: @Override         public void onReceive(Context context, Intent intent) {                 String action = intent.getAction();                 if (action != null && action.equals(UPDATE_ACTION)) {                         final AppWidgetManager manager = AppWidgetManager.getInstance (context);                         onUpdate(context, manager,                                         manager.getAppWidgetIds(new ComponentName(                                                         context, TVWidget.class)                                         )                         );                 }                 else {                         super.onReceive(context, intent);                 }         } This seems to work fine.

I’ve run into the following generalized question a lot recently: I have an event that occurs in the background. I want to update my activity, if the activity is on the screen. Otherwise, I want to raise a Notification.

Hence, the recipe for the activity-or-Notification pattern is: Define an action string you will use when the event occurs that you want to go to the activity or notification (e.g., com.commonsware.java.packages.are.fun.EVENT). Dynamically register a BroadcastReceiever in your activity, with an IntentFilter set up for the aforementioned action string and with a positive priority (the default priority for a filter is 0). This receiver should then have the activity do whatever it needs to do to update the UI based on this event. The receiver should also call abortBroadcast() to prevent others from getting it. Be sure to register the receiver in onStart() or onResume() and unregister the receiver in the corresponding onStop or onPause() method. Register in your manifest a BroadcastReceiver, with an <intent-filter> set up for the aforementioned action string. This receiver should raise the Notification. In your service (e.g., an IntentService), when the event occurs, call sendOrderedBroadcast(). And that’s it. If the activity is on-screen, its receiver will be registered, so it will get the event, process it, and cancel the broadcast. If the activity is not on-screen, its receiver will not be registered, so the event will go to the default handler, in the form of your manifest-registered BroadcastReceiver, which will raise the Notification.

On an HTC Hero, this EXTRA_OUTPUT doesn't even work. It doesn't put your picture in the file you specify, but it hands it to you thru a Mediastore uri. Apparently, the only way to get a full size picture is to do all camera handling in your app instead of using the IMAGE_CAPTURE intent.

I think Google have missed a trick on this one. They have defined standard intents for media capture, but not specified standard responses (ie. the "data" parameter in the onActivityResult Activity callback method). Other Android vendors (e.g. HTC Hero) have created their own Camera applications that handle the standard IMAGE_CAPTURE intent, but return different data & have different ways to save/return the image information. All I want is to be able to fire a IMAGE_CAPTURE intent from my own app, and get back a Uri reference to the captured image. Simple. I have no requirement to further manipulate the image .. I just need the Uri to store in my app's database for future reference.

Additionally, you can feel free to use the Search bar selection mechanism as a replacement for tabs since it’s really just a fast pivot on a data set. If you have more than 3 data sets, tabs become problematic since no more than 3 can be onscreen at once. For example, look at how we implemented the Profile switching mechanism below:

The good news for developers is you get this highly functional contacts feature for free if users choose to sync contact information into your app

The good news for developers is you get this highly functional contacts feature for free if users choose to sync contact information into your app. QuickContact for Android provides instant access to a contact's information and communication modes.

> Now I just want to update the GUI from this method. > Can I somehow call a method in PushEndpointDemo.java? No, for two reasons: 1. Because C2DMReceiver is a manifest-registered BroadcastReceiver and therefore has no access to any activities 2. There might not be an activity, since you have no control over the timing of when the C2DM message is received (e.g., the user pressed BACK, the user pressed HOME) > Do I need a Broadcast Intent to do this? Possibly. -- If you want to update an activity or else ignore the message, have C2DMReceiver send out a private broadcast, picked up by a receiver registered via registerReceiver() in the activity -- If you want to update an activity or else raise a notification, have C2DMReceiver send out an ordered broadcast, as described here: http://commonsware.com/blog/2010/08/11/activity-notification-ordered-... -- If you want to update a database, call startActivity() on an IntentService, and have it do the database I/O, plus possibly broadcast an Intent to update an activity/raise a notification.

I am just getting started with Android development and I have created a nice little widget that displays some info on my home screen. However, I now want to implement a Button on my widget that updates the info in my widget TextView.

Solved - I can confirm that an Activity is NOT needed if you want create a Button to update an Android AppWidget. I have been able to implement my AppWidgetProvider class such that it registers an android.appwidget.action.APPWIDGET_UPDATE intent-filter with the Broadcast receiver in the AndroidManifest.xml, which then fires the onUpdate event in the AppWidgetProvider class (which in turn then runs the UpdateService).

The UpdateService in my AppWidgetProvider class then uses onHandleIntent to run a private buildUpdate method - which registers the onClick event with a call to setOnClickPendingIntent as follows:

Their conclusion is that Android 2.1′s new speech-to-text thing works, just about, although there’s a delay of a few seconds while the phone crunches your spoken words and tries to get the gist of what you’re saying – and a few errors sneak in, particularly when dealing with those smaller words we tend to hurry over. Basically, it looks like you have an awkward choice to make – speak your messages then spend a bit of time awkwardly tidying up the few errors that will inevitably sneak in, or carry on as normal with traditional text input methods.

$ sudo gedit /etc/udev/rules.d/99-android.rules

$ sudo restart udev

$ adb kill-server $ adb start-server

Moreover I am not one of top developers nor any of my apps have been promoted by Android Market. I am just an one among of thousands of Android developers with not to well known apps. And what may be really surprising all my apps are free as Google do not allow developers from my country (Poland) to sell apps via Android Market!

So keep in mind these facts: None of my apps has been ever promoted in Top of Android Market I am providing only free apps (mostly due of Android Market limitations) Even if I would be able to sell apps I would not use it as main income source… (I believe that you still can make more from ads…)

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