Here is a solution that uses Ant. I must admit that getting Ant setup was a bit of a hassle, but it seems to be a widely used and powerful adjunct to Eclipse, so I believe it will turn out to be valuable for me in other ways.
Ant is the preferred solution for building Android SDK apps without Eclipse (as described here), but is not part of the ADT so you probably won't have it if you have just been using Eclipse.
So, the first step is to download and install Ant from here.
Next add Ant to your path and make sure that your path also points to the JDK (rather then the JRE). On Windows I found that I also had to create JAVA_HOME and point it to the root of the JDK.
We only need Ant for the auto-increment step - the intention is not to replace Eclipse and use it for the whole build - but it is useful to do a few steps in that direction to ensure that Ant is working. So, go to the root of your project and type
> android update project --path .
This creates a build.xml for your project. Once I had done that I was able to do
> ant release
and Ant built my project. If you want to keep going in that direction I found this article useful.
Next, I edited my project's new build.xml and added the following task (it can go anywhere, just not in the middle of another task/target)
<target name="update.buildnum">
<buildnumber/>
<!-- this task creates (and increments) Ant property 'build.number' which I use below -->
<echo>Current build number:${build.number}</echo>
<echoxml file="res/values/buildnum.xml">
<resources>
<string name="buildnum">${build.number}</string>
</resources>
</echoxml>
</target>
The task used above auto-increments a build number in a file (which it will create) called 'build.number' in your project's root. The rest of the task above puts the current build number into a resource string so that your application can retrieve it with this code:
String build = context.getString( com.your.app.R.string. buildnum );
int appBuild = ( int ) Integer.parseInt( build );
Some people will prefer a solution that writes the build number to the application code in the AndroidManifest.xml. Here is an answer that includes a task to do that, but it requires a 3rd party Ant task (xmltask), and I'm a bit hesitant to have a 3rd party task modifying my manifest (which is now pretty huge) on every build. If you do decide to use that task then the corresponding Android code to get the build number would be:
String packageName = ctx.getPackageName();
PackageInfo pInfo = ctx.getPackageManager().getPackageInfo( packageName, 0);
int appVer = pInfo.versionCode;
Finally, you need to get Eclipse to run this Ant task every time you do a build.
Go to your project's properties, find the Builders, and click the button to add a new Builder. There are tons of options here but you only need to specify a few.
- Give the builder some name by setting the Name: field.
- Select the Buildfile:. I used the 'browse workspace' option to select it, and then it filled the field with "${workspace_loc:/appname/build.xml}"
- Select targets from a list on the targets tab. In my case I had to remove the 'help' task (the default task in the build.mxl generated above), and then add the 'build.number' task. I suggest you only set a target for Manual Build:.
I moved the new Builder to be the first build step.
One issue with this solution is that every time you get Eclipse to deploy (run) your application it is considered to be a new manual build, even if the project hasn't changed. So, if you deploy your application to several devices, each device will have a different build with its own build number. One thing that will ameliorate this problem a bit is that Google says that a future ADT will allow for mutiple deployments in one operation.
This (above) was tested with Ant 1.8.4, Eclipse Indigo SR2 (3.7.2), ADT 20 preview 2 and SDK Tools 20, on Win7 32bit.
