One of the main changes in this version has to do with the permissions for apps. Before Android M, we were used to accepting the permissions of an app when we were about to download it; the play store showed us a list of permissions that an app has, and we needed to accept them in order to download and install it.

Runtime permissions

This has changed with the introduction of runtime permissions. The idea here is to accept the permission only when you need it. For instance, WhatsApp might not need access to your microphone until your make a call or leave a voice message.

This is something we need to take into account when we develop an app; it is a change for the developer who now needs to control what is to be done if the user doesn't accept the permission. Previously, we didn't have to do any controlling because it was an all-or-none choice at installation time; now, we have to consider the decision of the user at runtime.

Tip

Downloading the example code

You can download the example code files from your account at http://www.packtpub.com for all the Packt Publishing books you have purchased. If you purchased this book elsewhere, you can visit http://www.packtpub.com/support and register to have the files e-mailed directly to you.

Power-saving optimizations

There is another improvement regarding the battery life of our phones since Lollipop; this time, Google has introduced two new states: doze mode and app standby.

Doze mode improves the sleep efficiency of idle devices. If we turn off the screen and are not using the phone, we enter the idle state. Previously, applications could do network operations and continue working in the background; now, with the introduction of doze mode, the system periodically allows our apps to work in the background and perform other pending operations for a brief period of time. Again, this brings in some consideration while developing; for instance, in this mode, our apps can't access the network.

App standby is an induced idle mode for an app that has not been used for a while and doesn't have any processes running in the background. It is used for an app if it does not show any notifications and if the user has not explicitly asked it to be exempt from optimization. This idle mode prevents the app from accessing the network and executing pending jobs. When the power cable is connected, all apps in a standby state are released, and the idle restrictions are removed.

Text selection

In the previous versions, when a user selected text, a set of actions appeared on the action bar, such as copy, cut, and paste. With this version, we can show these actions and more, in a floating bar that will be presented above the selection:

Fingerprint authentication

In this version of Android, we can authenticate the use of our fingerprint. The authentication can be at a device level to unlock the phone, not just to unlock a specific app; so, we can authenticate users in our app based on how recently they unlocked their device.

We have a new object available, FingerprintManager, which will be in charge of the authentication and allow us to show a dialog requesting the fingerprint. We would need a device with a fingerprint sensor in order to use this feature.

Direct share

Direct share is a new addition to simplify the content sharing process. Previously, if we were in the gallery and wanted to share a picture to a contact in WhatsApp, we had to click on Share, find WhatsApp in the list of apps, and then find a contact inside WhatsApp to share this content. This process will be simplified, showing a list of contacts with whom you can share the information directly:

These are the main new features that have been released with Android 6 Marshmallow; the complete list can be seen at http://developer.android.com/preview/index.html.

Now that we've seen the main features of the latest Android version, we can introduce the app that we are going to develop during the book. This app will include most of these features, but we will also spend time in the components widely used in previous Android versions.

To master Android, we should be prepared to understand legacy code; for instance, we might have to work on an app that still uses ListView instead of RecyclerView, which is new. We will not always create apps from scratch with the latest components, especially if we are professional Android developers. Also, looking at previous components will help us understand the natural evolution of these components to have a better idea of how they are now.

We will start creating this app totally from scratch, starting with the initial design, having a look at the most used design and navigation patterns in Android, such as tabs at the top, a sliding menu on the left side, and so on.

The app that we will develop, MasteringAndroidApp, is one with server-side interaction. This app will show information that is stored in the cloud, and we will create the cloud component, making our app communicate with it. The topic we have chosen for the app is a job listing board, where we will create job offers on the server side, and the users of the app can read these offers and receive notifications.

You can easily customize the topic; this will be an example where you can change the information and create your own app with the same structure. In fact, it's better if you think of your own idea because we will discuss how to publish the app in Play Store and how to monetize it; we will add adverts, which will generate revenue when the users click on it. So, if you apply what you learn using your idea, by the time you finish the book, you will have an app ready to be distributed.

We will develop the app explaining the programming patterns that are most used in Android as well as concurrency techniques and different methods to connect to rest APIs or servers.

We'll not only be focusing on the backend, but also on the UI; by displaying the information in an efficient way, using lists and grids, downloading images from the Internet, and customizing fonts and views with the latest material design features.

We will learn the mechanism for debugging our apps, managing logs, and consider the memory usage while learning how to identify and prevent memory leaks.

Our app will have an offline mode based on a database, where we will store the content from the cloud. So, if the mobile loses connection, we can still show the information available when we were last online.

To complete our app, we will add extra features such as push notifications, crash reports, and analytics.

To finish, we will see how the Android build system works, exporting our app in different versions as well as obfuscating the code to protect it and prevent decompiling.

We have compressed a huge amount of information that will help you to master Android by the end of the book; however, before starting with our app, let's get the tools ready.

The tools that we will need during the book are the latest version of Android Studio, an Android SDK updated to Android M or later. It is also recommended that you have Genymotion, an emulator to test the app.

At the top of the website, you will have a link to download it depending on your OS version.

Once it's installed, we need to download an Android M SDK, which will provide all the classes and resources necessary to develop an app for a specific Android version. This is done through SDK Manager, a tool included inside Android Studio.

We can click on Tools | Android | SDK Manager or find a shortcut in the uppermost bar of Android Studio.

Once we open SDK manager, we will see a list of the available SDK platforms and SDK tools. We need to ensure that the latest version available is installed.

With this, we have all that we need to develop our app. In order to test it, it would be ideal to have Genymotion, which is an Android emulator that will help us test our app on different devices.

The reason we use this emulator instead of the Android default one is primarily the speed. Deploying an app in Genymotion is even quicker than using a physical device. Apart from this, we benefit from other features, such as resizable windows, copying and pasting from our computer, and other smaller details that are time consuming with the default emulator. It can be downloaded from https://www.genymotion.com.

All we need to do is install it, and once opened, we can add emulators with the same features included with existing devices.

In this chapter, we went through the important changes in the latest versions of Android, highlighting Android Marshmallow and Material Design.

We explained what we will do in the app that we'll be building through the course of this book and the tools that we'll need to create it.

In the next chapter, we will look at the existing design patterns in Android and start designing our app.