Build Your First Android App (With No Step Skipped)
Have you ever wanted to start learning how to build android applications?. Cool, Simply sit tight and I will take you through all the steps. (With no step skipped.)
# Create an Android Project
- In the Welcome to Android Studio window, click Start a new Android
Studio
project.
- Otherwise, If Android Studio is already open or if you already have an open
project, Click File > New > New Project...
- Otherwise, If Android Studio is already open or if you already have an open
project, Click File > New > New Project...
- In the Choose your project window, select Empty Activity and
click Next.
- In the Configure your project window:
- Type a name for your app. i.e Name: My Android App
- Type a package name for your app. It's typically your website domain name in reverse order plus the app name in lowercase. i.e Package name: com.stevenmwesigwa.myandroidapp
- Choose where you want to save your app if you want to save it in a different directory. i.e Save location: F:\ANDROID\learn
- Choose the programming language you want to use to write this app. In my case, I'll go with Java from the dropdown menu i.e Language: Java
- Choose the minimum android version you want your app to support. i.e Minimum API level: API 16: Android 4.1 (Jelly Bean)
- Click the Finish button.
- It may take some time as Android Studio prepares your app for the first time. Once it's done,
you
should see your editor appear like the one below.
- Open the Project window (View > Tool Windows > Project). Or use a keyboard
shortcut (ALT + 1)
.
- In the Project window, we have a couple of important files we will put more focus on namely :-
- app > java > com.stevenmwesigwa.myandroidapp
>
MainActivity
- This file acts as the main entry point for our app.
- app > res > layout >
activity_main.xml
- This is where the layout of the activity's user interface is defined.
- app > manifest >
AndroidManifest.xml
- This is where we define each component as where as define the main attributes about our app.
- Gradle Scripts > build.gradle
- As you may well notice, we have 2 build.gradle files. One for "app
Project" and another for "app Module".
- We'll use these files to configure 'build settings' to provide custom packaging options.
- As you may well notice, we have 2 build.gradle files. One for "app
Project" and another for "app Module".
- Let's now run our app. Here we have a couple of options namely:
-
# Running The App On An Actual Device (SECTION A).
- Connect your smart phone to your laptop or Desktop that you're currently working with using a USB cable. Make sure that your computer can recognize your phone. i.e That it is visible among the connected devices. If you're using Windows as your main operating system and your computer can't recognize your phone, you may need to install the appropriate USB driver for your smart phone.
-
# Enable USB Debugging on your smart phone.
- Depending on your phone's android version, how to achieve this may vary. These steps have been tested on "Android v7.0" or higher.
- Open Settings app.
- If your device uses Android v8.0 or higher, select System. Otherwise, proceed to the next step.
- Scroll down until you reach and select About phone.
- Scroll until you reach and select Build number 7 times
repeatedly.
- A tool tip may appear for a few seconds stating that "You are now a developer"
- To confirm, Tapping Build Number again may show a tooltip stating that "No need, you are already a developer".
- Tap your smart phone's "back" button once(previous screen), then scroll
up
or
down and select Developer options.
- In the Developer options window,Turn
On
the
top most button slider to allow "development settings".
- Scroll down or
up
till
you find USB debugging and turn On the
bottom
slider to allow "USB debugging".
-
# Running The App On Your Device(Smart phone) (SECTION B)
-
Once you've set your phone in debugging mode as explained above and your physical smart phone is still connected to your Computer / Laptop, make sure that the
Notification
window states that "Android system. USB debugging connected."
- Now we will edit the run/debug configuration settings to make sure that when we click the Run button in Android Studio, our app will run on our smart phone.
-
In Android Studio's tool bar, click Run > Edit Configurations...
- In the Run/Debug Configurations window, under
Deployment
Target Options, select "Open Select Deployment
Target
Dialog" .Then click the Ok button. This will allow us to have a window automatically opened up for us when we click the
Run
button in the tool bar for more Run options.
- Now click the Run button in the tool bar. Then click
Run
'app' to open up a Select Deployment Target
dialog box where we can click the connected smart phone to run our app.
- Now, as you can see from the image above, my smart phone was detected, but had a
label
of UNAUTHORIZED. For some reason it wasn't able to know that my phone
was
in debugging mode. I had to turn debugging Off and
On from Settings app > Developer options >
USB
debugging 'Debug mode when USB is connected' . After that,
my
smart phone prompted me with an Allow USB
debugging dialog box with the computer's RSA key fingerprint
Tap the box to 'Always allow from this
computer'.
Then click the Ok button to accept.
- After that, your smart phone should be successfully detected by Android Studio
as
shown in
the diagram below. i.e TECNO TECHNO WX3P (Android 7.0, API 24)
- Click Ok. Android Studio may prompt you with an Instant
Run dialog box. Instant Run allows you to push code changes without building
a
new Android Package (APK). But for our use case, we will keep things
simple
by clicking Proceed without Instant Run button.
- After that Android Studio will build an Android package for your smart phone and
run it. The building process may take some time depending on your machine.(It
took
2 minutes for my case).
- Yes!. This is it. We built our first app that displays "Hello World".
Hooray!!, If all went well, you should be able to see your
first Android app launching on your smart phone as shown in the diagram
below.
- If you made it to this point, am proud of you.
-
Once you've set your phone in debugging mode as explained above and your physical smart phone is still connected to your Computer / Laptop, make sure that the
Notification
window states that "Android system. USB debugging connected."
-
# Running The App On An Emulator
-
Assumptions:
- I assume you have an Android Emulator installed on your machine.
- . The emulator simply simulates (mimics) actual Android devices on your computer so that you can test your application on a variety of devices and Android API levels without needing to have multiple physical devices.
-
# Let's open android studio and try creating an Android Virtual Device (AVD).
- On the toolbar, Click Tools>AVD Manager.
- When the AVD Manager window opens up, Click the Create
Virtual Device... button.
- In the Virtual Device Configuration window on step
Select Hardware , Select Phone as
your category, then choose the virtual phone you plan on creating.
In my case, I went for Pixel 2. Leave other
settings as they are for now and click the Next
button.
- In the Virtual Device Configuration window on step
System Image , Select a system image of your
preference. In my case, I went for the latest at the time of
writing this article which is Q as the release
name with API Level 29. If the system image
wasn't download prior to this step, you will get a warning
A system image must be selected to
continue. To resolve this, click the
Download link next to your preferred system image
to download it.
- From the step above, the SDK Quickfix Installation
window will open up to show you the System Image download progress.
Wait until the download is complete. WARNING: Be prepared to provide
enough disk space for this system image. In my case, the system
image was 1.1 GB.
- Once installation is complete a screen displaying a successful installation process should show up. Click the Finish button.
- As you would notice, we no longer have a Download link next to our chosen System Image. Click Next button to proceed to the next step.
- In the Verify Configuration Window, Type in a name you would love displayed in our newly created system image. In my case, I labelled it "Pixel 2 API 29 Android 10".
- Finally, If all went well, an Android Device Manager window will pop up displaying a list of currently installed virtual devices.
- On the toolbar, Click Tools>AVD Manager.
-
# Run Your App On An Emulator.
Let's click the target device drop-down menu and choose which virtual device we would love to run our app on. In my case, I selected my newly created virtual device.( Pixel 2 API 29 Android 10 )- After selecting a virtual device to run on, Click the green Run button in the toolbar to run your app. Or you may go to the toolbar > Click Run > then Run 'app' which is equivalent to pressing SHIFT + F10 on a Windows machine.
- Android Studio will now install our app on our selected virtual device and will start the Emulator. After the install process is done, you should be able to see your app display "Hello World".
- That's it. You've now been able to build your first Android app. This is your first step to building more complex applications.
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- After selecting a virtual device to run on, Click the green Run button in the toolbar to run your app. Or you may go to the toolbar > Click Run > then Run 'app' which is equivalent to pressing SHIFT + F10 on a Windows machine.
-
-
# Resources:
I hope you learn a thing or two from this blog. Thanks for checking it out.
If anything is unclear or you wish to make any corrections, don't hesitate to leave a comment. Your feedback is greatly appreciated.
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Au revoir!