Making a Signed App with Android Studio

What You Need for This Project


Creating an app is useful so you understand how they are constructed, and essential for the later Trojaning projects, because you will need the self-signed certificate you create during this process.

Writing an App

When the install finishes, Android Studio launches. If it's not already running, launch it.

You should see the "Welcome to Android Studio" screen, as shown below.

On the right side, click "Start a new Android Studio project", as shown below.

In the "New Project" screen, enter an Application name of YOURNAME-hello, as shown below.

Don't use the literal text "YOURNAME" -- replace that with your own name.

Click Next.

The next screen asks which versions of Android you are targeting, as shown below.

Accept the default selection and click Next.

In the "Add an activity to Mobile" screen, accept the default selection of "Blank Activity" as shown below, and click Next.

In the "Choose options for your new file" screen, accept the default selections as shown below, and click Finish.

If you are using Windows, it will spend several minutes "Indexing".

Other messages go by, initializing things and "Building".

When all that stuff is done, a project page appears, as shown below.

If "Windows Firewall" boxes pop up, approve Java to access the Internet.

If a "Tip of the day" pops up, close it.

If a "Rendering problems" box appears, close it.

However, if a "Gradle project sync failed" message appears, as shown above, that means you have errors that matter, probably Java errors.

Resolving Java Errors

On my PC, Java worked! But that is a very rare exception.

Java fails to work most of the time. It is maddening, but there's no way to escape it.

The most common problem is that the Java files are installed in a directory that the application cannot find. It's been this way for many years, and somehow Java never fixes it.

Here's what I did, but your errors will probably be different. Expect this to take time and a lot of Googling.

In my case, there is a yellow bar saying "Gradle project sync failed...", and a pop-up box titled "Language Level Changed", as shown above.

In the pop-up box titled "Language Level Changed", click Yes.

The project reloads. Now the lower pane shows some Java error messages, as shown below.

Open a Terminal window, and execute this command:

The response tells you where Java is installed, as shown below.

On my Mac, Java is installed at


In the lower pane of Android Studio, click "Open SDK Settings".

As you can see below, the "JDK location" is wrong.

Copy and paste in the correct location, as shown below.

Then click OK.

Android Studio displays a yellow bar at the top, saying "Gradle sync in progress".

After that, the "Language Level Changed" box pops up again. Click Yes.

Exploring your App

When the Java problems are fixed, your project loads without errors, as shown below.

The left pane shows the files in your app.

A much easier way to control your app is to use the right pane. Click the activity_main.xml tab.

The center now shows the screen of a phone, showing "Hello world!" in tiny letters, as shown above. This is a graphical view of how your app will look on a phone.

Creating a Signed APK File

Android apps are distributed as signed APK files.

Android Studio should have a project open, such as your "Hello World" app.

In Android Studio, click Build, "Create Signed APK...".

In the "Module" box, accept the default selection of app and click Next.

The next box asks for a "Key store path" box, as shown below.

Click the "Create new..." button.

Fill in this box with the values shown below.

Warning: don't put a comma in any of the fields or it will stop with a Java error message.

Click OK.

Make a note of these items--you will need them later:
  • Key store path
  • alias
  • Key store password

The next box will automatically fill out itself, as shown below.

Click Next.

In the next box, click Finish, as shown below

A box pops up, saying "Signed APK's generated successfully", as shown below.

Running your App in the Genymotion Emulator

Launch a Genymotion emulated phone.

Drag the signed APK onto the emulated phone and drop it there.

The app should install and run :)


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Last modified 7-12-15