Difference between build.xml and project_name.xml

Question

I’ve been trying to understand the Android build process for several hours now.

I am using IntelliJ Idea for Android (this is a great tool). I opened a test project called IntelliJ "Hello Android". The project has this build.xml file name, the code below

 <?xml version="1.0" encoding="UTF-8"?> <project name="HelloAndroid" default="help"> <!-- The local.properties file is created and updated by the 'android' tool. It contains the path to the SDK. It should *NOT* be checked into Version Control Systems. --> <property file="local.properties" /> <!-- The ant.properties file can be created by you. It is only edited by the 'android' tool to add properties to it. This is the place to change some Ant specific build properties. Here are some properties you may want to change/update: source.dir The name of the source directory. Default is 'src'. out.dir The name of the output directory. Default is 'bin'. For other overridable properties, look at the beginning of the rules files in the SDK, at tools/ant/build.xml Properties related to the SDK location or the project target should be updated using the 'android' tool with the 'update' action. This file is an integral part of the build system for your application and should be checked into Version Control Systems. --> <property file="ant.properties" /> <!-- if sdk.dir was not set from one of the property file, then get it from the ANDROID_HOME env var. This must be done before we load project.properties since the proguard config can use sdk.dir --> <property environment="env" /> <condition property="sdk.dir" value="${env.ANDROID_HOME}"> <isset property="env.ANDROID_HOME" /> </condition> <!-- The project.properties file is created and updated by the 'android' tool, as well as ADT. This contains project specific properties such as project target, and library dependencies. Lower level build properties are stored in ant.properties (or in .classpath for Eclipse projects). This file is an integral part of the build system for your application and should be checked into Version Control Systems. --> <loadproperties srcFile="project.properties" /> <!-- quick check on sdk.dir --> <fail message="sdk.dir is missing. Make sure to generate local.properties using 'android update project' or to inject it through the ANDROID_HOME environment variable." unless="sdk.dir" /> <!-- Import per project custom build rules if present at the root of the project. This is the place to put custom intermediary targets such as: -pre-build -pre-compile -post-compile (This is typically used for code obfuscation. Compiled code location: ${out.classes.absolute.dir} If this is not done in place, override ${out.dex.input.absolute.dir}) -post-package -post-build -pre-clean --> <import file="custom_rules.xml" optional="true" /> <!-- Import the actual build file. To customize existing targets, there are two options: - Customize only one target: - copy/paste the target into this file, *before* the <import> task. - customize it to your needs. - Customize the whole content of build.xml - copy/paste the content of the rules files (minus the top node) into this file, replacing the <import> task. - customize to your needs. *********************** ****** IMPORTANT ****** *********************** In all cases you must update the value of version-tag below to read 'custom' instead of an integer, in order to avoid having your file be overridden by tools such as "android update project" --> <!-- version-tag: 1 --> <import file="${sdk.dir}/tools/ant/build.xml" /> </project> 

Then I did the following in IntelliJ Idea Build -> Generate Ant Build and selected the following options

• Creating a file with multiple Ant build files
• Output File Name: helloandroid
• Enabling compilation of user interface forms
• Use JSDK definitions from project files.

This led to the creation of three additional files

• helloandroid.properties
• helloandroid.xml
• module_helloandroid.xml

helloandroid.properties

 path.variable.maven_repository=C\:\\Users\\abc\\.m2\\repository jdk.home.android_4.1_platform=C\:/Program Files (x86)/Android/android-sdk 

helloandroid.xml

 <?xml version="1.0" encoding="UTF-8"?> <project name="HelloAndroid" default="help"> <!-- The local.properties file is created and updated by the 'android' tool. It contains the path to the SDK. It should *NOT* be checked into Version Control Systems. --> <property file="local.properties" /> <!-- The ant.properties file can be created by you. It is only edited by the 'android' tool to add properties to it. This is the place to change some Ant specific build properties. Here are some properties you may want to change/update: source.dir The name of the source directory. Default is 'src'. out.dir The name of the output directory. Default is 'bin'. For other overridable properties, look at the beginning of the rules files in the SDK, at tools/ant/build.xml Properties related to the SDK location or the project target should be updated using the 'android' tool with the 'update' action. This file is an integral part of the build system for your application and should be checked into Version Control Systems. --> <property file="ant.properties" /> <!-- if sdk.dir was not set from one of the property file, then get it from the ANDROID_HOME env var. This must be done before we load project.properties since the proguard config can use sdk.dir --> <property environment="env" /> <condition property="sdk.dir" value="${env.ANDROID_HOME}"> <isset property="env.ANDROID_HOME" /> </condition> <!-- The project.properties file is created and updated by the 'android' tool, as well as ADT. This contains project specific properties such as project target, and library dependencies. Lower level build properties are stored in ant.properties (or in .classpath for Eclipse projects). This file is an integral part of the build system for your application and should be checked into Version Control Systems. --> <loadproperties srcFile="project.properties" /> <!-- quick check on sdk.dir --> <fail message="sdk.dir is missing. Make sure to generate local.properties using 'android update project' or to inject it through the ANDROID_HOME environment variable." unless="sdk.dir" /> <!-- Import per project custom build rules if present at the root of the project. This is the place to put custom intermediary targets such as: -pre-build -pre-compile -post-compile (This is typically used for code obfuscation. Compiled code location: ${out.classes.absolute.dir} If this is not done in place, override ${out.dex.input.absolute.dir}) -post-package -post-build -pre-clean --> <import file="custom_rules.xml" optional="true" /> <!-- Import the actual build file. To customize existing targets, there are two options: - Customize only one target: - copy/paste the target into this file, *before* the <import> task. - customize it to your needs. - Customize the whole content of build.xml - copy/paste the content of the rules files (minus the top node) into this file, replacing the <import> task. - customize to your needs. *********************** ****** IMPORTANT ****** *********************** In all cases you must update the value of version-tag below to read 'custom' instead of an integer, in order to avoid having your file be overridden by tools such as "android update project" --> <!-- version-tag: 1 --> <import file="${sdk.dir}/tools/ant/build.xml" /> </project> 

module_helloandroid.xml

 <copy todir="${helloandroid.output.dir}"> <fileset dir="${module.helloandroid.basedir}/src"> <patternset refid="compiler.resources"/> <type type="file"/> <patternset refid="excluded.from.compilation.helloandroid"/> </fileset> <fileset dir="${module.helloandroid.basedir}/gen"> <patternset refid="compiler.resources"/> <type type="file"/> <patternset refid="excluded.from.compilation.helloandroid"/> </fileset> </copy> 

My question

• Why do we have different build.xml and helloandroid.xml files and two other files?
• Can these files be used during the build process?
• Can we edit these files to add another Ant build script?
• Why is build.xml showing an error in env.ANDROID_HOME ?
• What does helloandroid.xml show an error in jdk.home.1.6 ?

Answer 1

• Assembly files may contain other assembly files, this is common practice. your helloandroid.xml project helloandroid.xml exactly identical to the build.xml file, you can change any of them that you like and drop another. The build.xml file is the preferred convention for Ant. Your properties file is intended only to set properties, and the module file does not appear to be callable, but it probably exists, so you can include it and copy the file as it indicates.

• Yes, just turn them on. The helloandroid.properties file can be used instead of calling the general project.properties file, or you can leave it as is.

• Yes, please edit them, although they should be enough for an easy start.

• It looks like the ANDROID_HOME environment variable is not set. You can install it through IntelliJ, but I would recommend doing it at the level of your OS.

• It looks like your JAVA_HOME environment variable has not been set. You can install it through IntelliJ, but I would recommend doing it at the level of your OS.