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I've been trying to run simple programs that I obtained directly from the Source Code download for the book 'Beginning Android 4'. However, I have lots of problems with the build.xml files (see previous questions, which are unanswered). My latest is, which comes from the a simple Label demo program:
# ant debug
Buildfile: /home/me/src/ANDROID/MyProjects/Label/build.xml
BUILD FAILED
Target "debug" does not exist in the project "LabelDemo".
I then checked with other working build.xml files and as fasr as I can tell, grepping thru the text of the file, 'debug' doesn't exist there either. But they work.
So, I obviously must be creating build.xml files incorrectly. What is the correct way to create the build file for an Android project (from the command-line).
Run android update project -p ..., where the ... is the path to the project. This will create or update the build.xml and related command-line build files. This assumes that your SDK's tools/ directory in your PATH; otherwise, you will need to fully-qualify the path to the android command.
来源：https://stackoverflow.com/questions/15718907/how-to-create-build-xml-for-an-android-project