Attention! Capitalistic content following!

Since the Android Market has been started it does support free applications in their store market. Though Google announced that we will be able to add commercial products soon — the actual question is: When?

Until now nothing happened at this front and therefore, I guess it might still take a while before developers can earn some money with their applications. However, the Android Market is being used very heavily already — free software is popular everywhere! So users keep downloading applications from the Market massively. In order to make some cents out of this in future (when commercial products can be sold) you must be up with your application already!

My point is: you need to start grabbing potential customers now, even though they do not spend any money on applications — yet.

Of course, I don’t want you to give your developed apps away for free. Most applications took a long time to develop and you (or your company) spent a lot of time and put in quite some effort to create this neat peace of software. This all creates costs on the developer’s side (if you are not a student who is programming for fun without the need to make a living — again: yet) which needs to be compensated at some point.

How you grab potential customers

The application you want to sell might be finished already (don’t forget to sign it!). It is too valuable to give it away for free but you want users already – for selling the full version to them later or just to get some feedback. The best way to get users using your application is the Android Market. Hence, you need to be in there!

Create a demo/trial version of your application. There are plenty of ways on how to create a demo version. However, as we do not know at which date commercial applications will be available on the Android Market I suggest to “cripple” your full version in order to demonstrate your applications capabilities. A time limitation might be possible too but due to the uncertain time line I would just prefer “crippling”. Though, I am not a fan of that, usually.

Once you have done this you can upload your application to the Android Market at: http://market.android.com/publish/

Now you just wait and let the installation / download counter increase minute by minute (image above is 6 hours after program upload!). Once the Android Market supports commercial applications you can upload your full version, change the application’s preferences to “commercial” / “paid” content and charge a little fee like say $2. Let us do some maths here for getting a rough idea on what this can bring. In case you gained 20,000 active installations after 2 months, you are having 20,000 users of your application. Meaning: 20,000 users really like your app – though it is crippled. Let us assume half of them (10,000 users) would really spend $2 on the full version. Once you release your full version you will get $20,000 instantly with the release and you are a happy developer!

To be honest, developing applications is not just about money. It is a lifestyle – an art! However, even artists have to eat sometimes or spend money on Absynthe in the evening; so we need some bucks too. I think $2 for a nice app is nearly nothing and everyone can afford this. Just to honor hard work of programming.

If you want to publish an Android application you first need to write it

The result of your programming will be an .APK file which is the actual program binary of your application. However, the .APK file your compiler creates can only be used with the emulator on your desktop PC or Mac. You cannot use the same .APK file to install and run your app on your Android phone (like the G1, Kogan Agora, or else).

Why is that? Well, Google wants to protect its phone users from installing and running fraudulent software on their devices. Therefore, each and every application needs to be signed with a valid certificate that ensures where the application comes from. Meaning: the developer (you!) signs the application with his/her certificate to make sure it is always traceable where the application comes from. There are a bunch of more reasons to this so lets check out what Google is saying about this topic:

The important points to understand about signing Android applications are:

• All applications must be signed. The system will not install an application that is not signed.
• You can use self-signed certificates to sign your applications. No certificate authority is needed.
• When you are ready to publish your application, you must sign it with a suitable private key. You can not publish an application that is signed with the default key generated by the SDK tools.
• The system tests a signer certificate’s expiration date only at install time. If an application’s signer certificate expires after the application is installed, the application will continue to function normally.
• You can use standard tools — Keytool and Jarsigner — to generate keys and sign your application .apk files.

3 Easy Steps for getting what you need to sign Applications
(this needs to be done once only)

1. Create a keystore with your own keys and certificates
   First of all you need to create a keystore which stores your certificate. A certificate is always created by the developer himself without any interaction from Google. This actually means that Google does not approve certificates before you can use them for signing your application. (Note: other companies like RIM, Nokia/Symbian, Windows Mobile do such things.)

   Once you installed a Java SDK you can use the default keytool application to create your own keystore. A Java SDK is installed by default on Mac OS X machines and can also be installated additionally on your Windows PC or Linux machine. If you have Java SDK running on your system just go to any prompt and type in the following:

   Windows: START»Command
   $ keytool -genkey -v -keystore my-release-key.keystore -alias alias_name -keyalg RSA -validity 10000

   Windows: Mac: Terminal
   $ keytool -genkey -v -keystore my-release-key.keystore -alias alias_name -keyalg RSA -validity 10000

   You will be asked to enter a password for your keystore. Choose it wisely and remember it! You will need it every time you sign an APK file. Follow the instructions and finalize the creation of your keystore.

2. Place the keys at a location that makes sense
   Choosing the right place for your keystore is quite important. Let’s imagine you write more than one application so it would not make that much sense to put this keystore into the project directory of the application you are currently working with. As I am using Mac OS X Leopard and Eclipse I got a project directory like /Users/YOUR_NAME/Documents/workspace/DialANumber. However, as mentioned before a more global approach might make so I copied the keystore to the directory:

   /Users/YOUR_NAME/Documents/workspace/androidkeys

   So we got our keystore prepared for signing now.

3. Write a short script to make your life easier
   Just to make the life easier I wrote a short script which can be used each time to sign your Android APK file. You can download it below and place it in the same directory you placed the keystore at (see point 2).

   Download: Signing Script for Easy .APK Signing

Once you have done this we are ready for signing our application!

3 Easy Steps for getting your Application signed
(this needs to be done each time you build a binary that is going to be published)

1. Build your application

   Right click your Android project in Eclipse and select Android Tools » Export Unsigned Application Package.... Follow the instructions and remember the directory your placed the .APK file at. E.g. cd /Users/YOUR_NAME/Documents/workspace/DialANumber/deploy/

2. Go to your keystore & script directory

   cd /Users/YOUR_NAME/Documents/workspace/androidkeys/

3. Sign your application
   In your androidkeys directory you need to execute:

   ./sign-mac-example.sh ../DialANumber/deploy/DialANumber.apk
Enter passphrase:

   After you entered your passphrase the application should be signed.

You can now upload your app to your server and install it on an Android phone or you can even publish it on the Android Market!

Sources:

• Android Documentation
• Anddev.org howto

P.S.: The complete signing process (the part you need to do each time you sign an app) could be integrated better into Eclipse. I hope Google improves this in future. They could add an entry like Android Tools » Export Signed Application Package... so the developer just needs to enter the passphrase in a GUI dialog. This would make everyone’s life much easier. Perhaps a bored Eclipse PlugIn developer might want to write a plugin for this? It would make many people happy I guess