Goings on app android

How to detect Android application open and close: Background and Foreground events.

Dec 17, 2017 · 4 min read

This question seems to come up a lot. Especially if you are just starting out with Android developme n t. It’s simply because there is nothing obvious built into the Android SDK enabling developers to hook into application lifecycle events. Activities and Fragments have all the callbacks under the sun to detect lifecycle change, but there is nothing for the whole application. So how do you detect when a user backgrounds and foregrounds your app. This is an example of how your could detect Application lifecycle events. Feel free to adjust and enhance it to suit your needs, but this idea should be enough to work for most applications with one caveat, it will only work for Android API level 14+(IceCreamSandwich 🍦🥪).

Detecting App Lifecycle Evnts

Backgrounding

ComponentCallbacks2 — Looking at the documentation is not 100% clear on how you would use this. However, take a closer look and you will noticed the onTrimMemory method passes in a flag. These flags are typically to do with the memory availability but the one we care about is TRIM_MEMORY_UI_HIDDEN. By checking if the UI is hidden we can potentially make an assumption that the app is now in the background. Not exactly obvious but it should work.

Foregrounding

ActivityLifecycleCallbacks — We can use this to detect foreground by overriding onActivityResumed and keeping track of the current application state (Foreground/Background).

Implementing a Foreground and Background Handler

First, lets create our interface that will be implemented by a custom Application class. Something as simple as this:

Next, we need a class that is going to implement the ActivityLifecycleCallbacks and ComponentCallbacks2 we discussed earlier. So lets create an AppLifecycleHandler and implement those interfaces and override the methods required. And lets take an instance of the LifecycleDelegate as a constructor parameter so we can call the functions we defined on the interface when we detect a foreground or background event.

We outlined earlier that we could use onTrimMemory and the TRIM_MEMORY_UI_HIDDEN flag to detect background events. So lets do that now.

Add this into the onTrimMemory method callback body

So now we have the background event covered lets handle the foreground event. To do this we are going to use the onActivityResumed. This method gets called every time any Activity in your app is resumed, so this could be called multiple times if you have multiple Activities. What we will do is use a flag to mark it as resumed so subsequent calls are ignored, and then reset the flag when the the app is backgrounded. Lets do that now.

So here we create a Boolean to flag the application is in the foreground. Now, when the application onActivityResumed method is called we check if it is currently in the foreground. If not, we set the appInForeground to true and call back to our lifecycle delegate ( onAppForegrounded()). We just need to make one simple tweak to our onTrimMemory method to make sure that sets appInForeground to false.

Now we are ready to use our AppLifecycleHandler class.

AppLifecycleHandler

Now all we need to do is have our custom Application class implement our LifecycleDelegate interface and register.

And there you go. You now have a way of listening to your app going into the background and foreground.

This is only supposed to be used as an idea to adapt from. The core concept using onTrimMemory and onActivityResumed with some app state should be enough for most applications, but take the concept, expand it and break things out it to fit your requirements. For the sake of brevity I won’t go into how we might do multiple listeners in this post, but with a few tweaks you should easily be able to add a list of handlers or use some kind of observer pattern to dispatch lifecycle events to any number of observers. If anyone would like me to expand on this and provide a multi listener solution let me know in the comments and I can set something up in the example project on GitHub.

Update: Using Android Architecture Components

Thanks to Yurii Hladyshev for the comment.

If you are using the Android Architecture Components library you can use the ProcessLifecycleOwner to set up a listener to the whole application process for onStart and onStop events. To do this, make your application class implement the LifecycleObserver interface and add some annotations for onStop and onStart to your foreground and background methods. Like so:

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Running Apps on Your Device

When building an Android app, it’s important that you always test your application on a real device in addition to emulators. This page describes how to set up your development environment and Android-powered device for testing and debugging on the device.

If you want an ideal SIM-unlocked phone to test on, then you might consider a Pixel phone.

Plug in your device to your computer with a USB cable. If you’re developing on Windows, you might need to install this universal ADB USB driver or find your specific USB driver for your device.

The next step is to enable USB debugging so your phone can interact with your computer in a developer mode.

The following steps are needed:

1. (Windows Only) Install this ADB Driver
2. Plug-in your Android Device to Computer via USB
3. Open the «Settings» App on the Device
4. Scroll down to bottom to find «About phone» item
5. Scroll down to bottom to find «Build number» section
6. Tap on «Build Number» 7 times in quick succession
7. You should see the message «You are now a developer!»
8. Go back to main «Settings» page
9. Scroll down bottom to find «Developer options» item
10. Turn on «USB Debugging» switch and hit «OK»
11. Unplug and re-plug the device
12. Dialog appears «Allow USB Debugging?»
13. Check «Always allow from this computer» and then hit «OK»

Watch this video tutorial for a visual guide to getting USB debugging enabled.

Now, we can launch apps from Android Studio onto our device:

1. Select one of your projects and click «Run» from the toolbar.
2. In the «Choose Device» window that appears, select the «Choose a running device» radio button, select the device, and click OK.

Once Gradle finishes building, Android Studio should install the app on your connected device and start it.

Not seeing your device in the «Choose Device» window? Try the following:

• Unplug your device from the USB port on the computer
• Restart the device by powering off and back on
• Verify that Settings => Developer options => USB Debugging is enabled
• Quit and re-launch Android Studio
• Force restart ADB from the «Android Device Monitor»
• Plug your device back into the USB port on the computer
• Unlock the device and press «OK» on any dialog displayed

Now the phone should work as a debugging device as expected!

Still Not Working?

If after plugging the device into the computer and you don’t see any message about authorizing the device, then you may need to purchase another USB cable. Not all USB cables are enabled for data transfer. If there’s a chance that your cable may be a charging only cable, you can purchase a USB-C cable for Pixel or the micro-USB cable for Nexus 6 and prior.

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5 Free Ways to Run Android Apps on Your PC

Want to use Android apps on a PC? These are the apps, services, and OSes that can make it happen.

Ever wish you could run an Android app or game on your PC so you weren’t relegated to a tiny phone screen? Maybe you need to test a feature on Android, but don’t have an Android device handy. Your options will depend on what mobile device you own or what version of Windows you’re running, but here are a few ways to run Android (and its apps) on your computer.

Mirror Your Phone With Windows

For apps installed on your phone, you don’t need anything fancy to get Android on your PC. Microsoft’s Your Phone app allows you to connect your Android mobile device to Windows in order to access apps, view notifications and photos, and send messages. You can even add Android apps to Favorites or pin them directly to the Windows taskbar.

If you want to mirror your phone screen directly, just click the phone screen image in the Your Phone desktop app. Grant permission to the app on your phone, and your phone screen will be displayed in Windows. You can then navigate the phone screen with the click of the mouse.

This isn’t always the ideal solution. While the feature will work with many Android phone manufacturers, it works best with Samsung phones. Some features require a Windows 10 PC running the May 2020 Update or later with at least 8GB of RAM and Android 11. If you’re looking to play games, this may come with some delay and graphical blurriness, and you won’t be able to easily share files from your PC directly to an app in Android. But for quick access to Android apps you already have installed, it definitely works in a pinch.

Run Your Favorite Apps With BlueStacks

If you’re just looking to run a couple apps and don’t need the emulator to look like Android, you should try BlueStacks. Over the years, it’s become the best Android app emulator around, and it’s packed with features that ensure your apps and games run smoothly. Since it uses virtualization to emulate Android, you’ll want to jump into your computer’s BIOS and enable Intel VT-x or AMD-V, if your computer supports it, for best performance.

Install BlueStacks as you would any other Windows or Mac app. BlueStacks 5, the latest version of the software, takes up 5GB of space on your computer (plus any apps you download). Open the app, and you’ll be greeted with a customized home screen and access to the Play Store. Download any apps you want, and they will appear on the BlueStacks home screen and your Windows desktop as their own shortcuts. Just double-click an icon to run the app in question.

BlueStacks is great for apps that don’t have corresponding desktop apps, but the emulator really shines when it comes to games. The emulator features built-in mappings for your mouse and keyboard, which you can customize to the touch controls you find on different Android games.

You can also adjust the resolution, DPI, FPS, and amount of CPU or RAM allocated to the emulator, ensuring you get the best balance between speed and graphical fidelity. (This is useful given that BlueStacks is fairly resource-intensive, as many virtual machines are.)

BlueStacks does, unfortunately, come with some ads and clutter, but it’s not as intrusive as it once was, and it’s a small price to pay for the functionality you get—especially considering the Android version options it offers.

Emulate Full Android Experience With Genymotion

If you’re looking to explore the Android operating system itself—rather than individual apps—Genymotion is a decent emulator. Its main product is designed for developers and costs money to use, but there is a free version of the software you can download for personal use; you just need to first create an account on the website.

Genymotion uses VirtualBox to emulate Android, so you’ll either need to have VirtualBox installed on your PC or download the version with VirtualBox bundled. Install it like you would any other program, ensuring you select the Personal Use version during the wizard. (And, like BlueStacks, you’ll want to enable Intel VT-x or AMD-V from your computer’s BIOS if you have it.)

When you start Genymotion, it’ll present you with a list of device templates you can install—this determines the screen resolution, Android version, and resources allotted to the emulator. Install the template you want and double-click it to enter Android. You’ll be able to navigate around the home screen, launch apps, and emulate certain events like GPS location.

Note that you’ll start with a very barebones version of Android that doesn’t even come with many of Google’s apps or modern features, though you can add the Play Store by clicking the Open Gapps icon in the sidebar to install it.

Also, no matter which template you choose, you won’t get any custom versions of Android—picking the Samsung Galaxy S10 template, for example, won’t get you Samsung’s One UI. It just determines the resolution and specs of the virtual machine. (Genymotion does support Android versions from 4.4 all the way up to 10.0, though.)

Genymotion works well for exploring Android’s settings and other built-in features, though I wouldn’t necessarily use it to run individual apps, as it doesn’t integrate as well with your PC as something like BlueStacks. If Genymotion doesn’t suit your needs, Google’s official Android software development kit also comes with an Android emulator, though setup is more complex.

Run Android Directly on Your PC With Android-x86

If you’re looking for something a bit more full-featured, the Android-x86 project gets you as close as you can get to true Android on your PC. Android-x86 is an open-source project that ports Android to the x86 platform, allowing you to run it on your computer instead of an ARM-based phone or tablet.

To run Android-x86, you have a couple of options. If you want to run Android on its own, as a desktop operating system for your PC, you can download it as an ISO disc image and burn it to a USB drive with a program like Rufus. Then, insert that USB drive into the PC in question, reboot, and enter the boot menu (usually by pressing a key like F12 during the boot process).

By booting from your Android-x86 USB drive, you’ll either be able to run Android in a live environment—without having any effect on your PC—or install it to your PC’s hard drive for permanent usage (and better performance).

Alternatively, if you want to run Android-x86 on top of your existing operating system, you can download the disc image and run it inside VirtualBox. This is, again, a bit more advanced if you aren’t familiar with VirtualBox, but our guide to running Windows on a Mac can get you acquainted with the process.

The official site has some tips for getting Android-x86 up and running in a virtual machine as well. It’s more work than using something like BlueStacks, but it’s also closer to pure Android, which is a nice perk.

Install Android Apps From the Amazon Appstore

With Windows 11, Microsoft adds built-in support for Android apps, but for now it’s limited to those enrolled in the Windows Insider beta program, who can currently play around with 50 apps from the Amazon Appstore. You’ll also need a PC that can run Windows 11.

Windows 11 taps into a feature called Windows Subsystem for Android, which makes Android apps compatible with Microsoft’s own OS. You’ll need to install the Amazon Appstore from the Microsoft Store, which will prompt you to install Windows Subsystem. Here’s a full rundown.

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