Creating an Android Project

This lesson shows you how to create a new Android project with Android Studio and describes some of the files in the project.

1. In Android Studio, create a new project:
   • If you don't have a project opened, in the Welcome screen, click New Project.
   • If you have a project opened, from the File menu, select New Project. The Create New Project screen appears.
2. Fill out the fields on the screen. For Application Name use "My First App". For Company Domain, use "example.com". For the other fields, use the default values and click Next

   Here's a brief explanation of each field:

   • Application Name is the app name that appears to users.
   • Company domain provides a qualifier that will be appended to the package name; Android Studio will remember this qualifier for each new project you create.
   • Package name is the fully qualified name for the project (following the same rules as those for naming packages in the Java programming language). Your package name must be unique across all packages installed on the Android system. You can Edit this value independently from the application name or the company domain.
   • Project location is the directory on your system that holds the project files.
3. Under Target Android Devices, accept the default values and click Next.

   The Minimum Required SDK is the earliest version of Android that your app supports, indicated using the API level. To support as many devices as possible, you should set this to the lowest version available that allows your app to provide its core feature set. If any feature of your app is possible only on newer versions of Android and it's not critical to the app's core feature set, you can enable the feature only when running on the versions that support it (as discussed in Supporting Different Platform Versions).

4. Under Add an Activity to Mobile, select Empty Activity and click Next.

Activities

An activity is one of the distinguishing features of the Android framework. Activities provide the user with access to your app, and there may be many activities. An application will usually have a main activity for when the user launches the application, another activity for when she selects some content to view, for example, and other activities for when she performs other tasks within the app. See Activities for more information.

5. Under Customize the Activity, accept the default values and click Finish.

Your Android project is now a basic "Hello World" app that contains some default files. Take a moment to review the most important of these:

app/src/main/java/com.example.myfirstapp/MainActivity.java

This file appears in Android Studio after the New Project wizard finishes. It contains the class definition for the activity you created earlier. When you build and run the app, the Activity starts and loads the layout file that says "Hello World!"

app/src/main/res/layout/activity_main.xml

This XML file defines the layout of the activity. It contains a TextView element with the text "Hello world!".

app/src/main/AndroidManifest.xml

The manifest file describes the fundamental characteristics of the app and defines each of its components. You'll revisit this file as you follow these lessons and add more components to your app.

app/build.gradle

Android Studio uses Gradle to compile and build your app. There is a build.gradle file for each module of your project, as well as a build.gradle file for the entire project. Usually, you're only interested in the build.gradle file for the module, in this case the app or application module. This is where your app's build dependencies are set, including the defaultConfig settings:

• compiledSdkVersion is the platform version against which you will compile your app. By default, this is set to the latest version of Android available in your SDK. By default, this is set to the latest version of Android SDK installed on your development machine. You can still build your app to support older versions, but setting this to the latest version allows you to enable new features and optimize your app for a great user experience on the latest devices.
• applicationId is the fully qualified package name for your application that you specified in the New Project wizard.
• minSdkVersion is the Minimum SDK version you specified during the New Project wizard. This is the earliest version of the Android SDK that your app supports.
• targetSdkVersion indicates the highest version of Android with which you have tested your application. As new versions of Android become available, you should test your app on the new version and update this value to match the latest API level and thereby take advantage of new platform features. For more information, read Supporting Different Platform Versions.

See Building Your Project with Gradle for more information about Gradle.

Note also the /res subdirectories that contain the resources for your application:

drawable-<density>/

Directories for drawable resources, other than launcher icons, designed for various densities.

layout/

Directory for files that define your app's user interface like activity_main.xml, discussed above, which describes a basic layout for the MainActivity class.

menu/

Directory for files that define your app's menu items.

mipmap/

Launcher icons reside in the mipmap/ folder rather than the drawable/ folders. This folder contains the ic_launcher.png image that appears when you run the default app.

values/

Directory for other XML files that contain a collection of resources, such as string and color definitions.

To run the app, continue to the next lesson.