Task 1: Create a new project

What you'll learn

How to create a project in Android Studio.
How to create an emulated Android device.
How to run your app on the emulator.
How to run your app on your own physical device, if you have one.

In this step, you will create a new Android project for your first app. This simple app displays the string "Hello World" on the screen of an Android virtual or physical device.

Here's what the finished app will look like:

Step 1: Create a new project

1. Open Android Studio.

2. In the Welcome to Android Studio dialog, click Start a new Android Studio project.

3. Select Basic Activity (not the default). Click Next.

5. Give your application a name such as My First App.

6. Make sure the Language is set to Java.

7. Leave the defaults for the other fields.

8. Click Finish.

After these steps, Android Studio:

Creates a folder for your Android Studio project called MyFirstApp. This is usually in a folder called AndroidStudioProjects below your home directory.
Builds your project (this may take a few moments). Android Studio uses Gradle as its build system. You can follow the build progress at the bottom of the Android Studio window.
Opens the code editor showing your project.
At this point, your screen should look a bit less cluttered, similar to the screenshot shown below.

Step 2: Explore the project structure and layout

The upper left of the Android Studio window should look similar to the following diagram:

Based on you selecting the Basic Activity template for your project, Android Studio has set up a number of files for you. You can look at the hierarchy of the files for your app in multiple ways, one is in Project view. Project view shows your files and folders structured in a way that is convenient for working with an Android project. (This does not always match the file hierarchy! To see the file hierarchy, choose the Project files view by clicking (3).)

1. Double-click the app (1) folder to expand the hierarchy of app files. (See (1) in the screenshot.)

2. If you click Project (2), you can hide or show the Project view. You might need to select View > Tool Windows to see this option.

3. The current Project view selection (3) is Project > Android.

In the Project > Android view you see three or four top-level folders below your app folder: manifests, java, java (generated) and res. You may not see java (generated) right away.

1. Expand the manifests folder.

This folder contains AndroidManifest.xml. This file describes all the components of your Android app and is read by the Android runtime system when your app is executed.

2. Expand the java folder. All your Java language files are organized here. The java folder contains three subfolders:

com.example.myfirstapp: This folder contains the Java source code files for your app.
com.example.myfirstapp (androidTest): This folder is where you would put your instrumented tests, which are tests that run on an Android device. It starts out with a skeleton test file.
com.example.myfirstapp (test): This folder is where you would put your unit tests. Unit tests don't need an Android device to run. It starts out with a skeleton unit test file.

3. Expand the res folder. This folder contains all the resources for your app, including images, layout files, strings, icons, and styling. It includes these subfolders:

drawable: All your app's images will be stored in this folder.
layout: This folder contains the UI layout files for your activities. Currently, your app has one activity that has a layout file called activity_main.xml. It also contains content_main.xml, fragment_first.xml, and fragment_second.xml.
menu: This folder contains XML files describing any menus in your app.
mipmap: This folder contains the launcher icons for your app.
navigation: This folder contains the navigation graph, which tells Android Studio how to navigate between different parts of your application.
values: This folder contains resources, such as strings and colors, used in your app.

Step 4: Create a virtual device (emulator)

In this task, you will use the Android Virtual Device (AVD) manager to create a virtual device (or emulator) that simulates the configuration for a particular type of Android device.

The first step is to create a configuration that describes the virtual device.

1. In Android Studio, select Tools > AVD Manager, or click the AVD Manager icon in the toolbar.

2. Click "+Create Virtual Device". (If you have created a virtual device before, the window shows all of your existing devices and the "+Create Virtual Device" button is at the bottom.) The Select Hardware window shows a list of pre-configured hardware device definitions.

3. Choose a device definition, such as "Pixel 2", and click Next. (For this codelab, it really doesn't matter which device definition you pick).

4. In the System Image dialog, from the Recommended tab, choose the latest release. (This does matter.)

5. If a Download link is visible next to a latest release, it is not installed yet, and you need to download it first. If necessary, click the link to start the download, and click Next when it's done. This may take a while depending on your connection speed.

Note: System images can take up a large amount of disk space, so just download what you need.

6. In the next dialog box, accept the defaults, and click Finish.

The AVD Manager now shows the virtual device you added.

7. If the Your Virtual Devices AVD Manager window is still open, go ahead and close it.

Step 5: Run your app on your new emulator

1. In Android Studio, select Run > Run ‘app' or click the Run icon in the toolbar. The icon will change when your app is already running.

If you get a dialog box stating "Instant Run requires that the platform corresponding to your target device (Android N...) is installed" go ahead and click Install and continue.

2. In Run > Select Device, under Available devices, select the virtual device that you just configured. This menu also appears in the toolbar.

The emulator starts and boots just like a physical device. Depending on the speed of your computer, this may take a while. You can look in the small horizontal status bar at the very bottom of Android Studio for messages to see the progress.

Messages that might appear briefly in the status bar:

Gradle build running
Waiting for target device to come on line
Installing APK
Launching activity

Once your app builds and the emulator is ready, Android Studio uploads the app to the emulator and runs it. You should see your app as shown in the following screenshot.

Note: It is a good practice to start the emulator at the beginning of your session. Don't close the emulator until you are done testing your app, so that you don't have to wait for the emulator to boot again. Also, don't have more than one emulator running at once, to reduce memory usage.

Step 6: Run your app on a device (if you have one)

What you need:

An Android device such as a phone or tablet.
A data cable to connect your Android device to your computer via the USB port.
If you are using a Linux or Windows OS, you may need to perform additional steps to run your app on a hardware device. Check the Run Apps on a Hardware Device documentation. On Windows, you may need to install the appropriate USB driver for your device. See OEM USB Drivers.

Run your app on a device

To let Android Studio communicate with your device, you must turn on USB Debugging on your Android device.

On Android 4.2 and higher, the Developer options screen is hidden by default. To show Developer options and enable USB Debugging:

1. On your device, open Settings > About phone and tap Build number seven times.

2. Return to the previous screen (Settings). Developer options appears at the bottom of the list. Tap Developer options.

3. Enable USB Debugging.

Now you can connect your device and run the app from Android Studio.

1. Connect your device to your development machine with a USB cable. On the device, you might need to agree to allow USB debugging from your development device.

2. In Android Studio, click Run in the toolbar at the top of the window. (You might need to select View > Toolbar to see this option.) The Select Deployment Target dialog opens with the list of available emulators and connected devices.

3. Select your device, and click OK. Android Studio installs the app on your device and runs it.

Note: If your device is running an Android platform that isn't installed in Android Studio, you might see a message asking if you want to install the needed platform. Click Install and Continue, then click Finish when the process is complete.

Troubleshooting

If you're stuck, quit Android Studio and restart it.

If Android Studio does not recognize your device, try the following:

1. Disconnect your device from your development machine and reconnect it.

2. Restart Android Studio.

If your computer still does not find the device or declares it "unauthorized":

1. Disconnect the device.

2. On the device, open Settings->Developer Options.

3. Tap Revoke USB Debugging authorizations.

4. Reconnect the device to your computer.

5. When prompted, grant authorizations.

If you are still having trouble, check that you installed the appropriate USB driver for your device. See the Using Hardware Devices documentation.

Check the troubleshooting section in the Android Studio documentation.

Step 7: Explore the app template

When you created the project and selected Basic Activity, Android Studio set up a number of files, folders, and also user interface elements for you, so you can start out with a working app and major components in place. This makes it easier to build your application.

Looking at your app on the emulator or your device, in addition to the Next button, notice the floating action button with an email icon. If you tap that button, you'll see it has been set up to briefly show a message at the bottom of the screen. This message space is called a snackbar, and it's one of several ways to notify users of your app with brief information.

At the top right of the screen, there's a menu with 3 vertical dots. If you tap on that, you'll see that Android Studio has also created an options menu with a Settings item. Choosing Settings doesn't do anything yet, but having it set up for you makes it easier to add user-configurable settings to your app.

Later in this codelab, you'll look at the Next button and modify the way it looks and what it does.

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