A Gradle plugin for Android which generates both Java and XML constants as part of the build process.
In short: To define constants that are accessible from everywhere in your Android app.
In long: There are two ways to define constants in Android. Both have their limitations.
- Creating constants using
buildConfigFieldonly adds entries toBuildConfig.javawhich means you cannot access them via XML. - Creating a custom
constants.xmlresource file with entries like<string name="constant">constant_value</string>lets you easily reference the constant via@string/constantin XML, but requires you to have aContextobject on the Java side to get the value usinggetResources().getString(R.string.constant).
None of the above solutions is ideal. This plugin lets you specify constants in your build.gradle file
that will be translated into both a Java and an XML-based version with the same constant value.
The plugin creates a new task per build type, e.g. generateDebugBuildConstants. It hooks into the build process ahead of the processDebugResources task so it will be executed every time you assemble your project. It supports incremental builds, i.e. if none of the inputs or outputs have changed, Gradle can skip the task (up-to-date).
The plugin currently supports Integer, Boolean and String data types.
You can specify the constants using a closure in your build.gradle file like this:
buildConstants {
constants {
aBoolean = true
aString = 'string'
aNumber = 123
}
}The plugin will then generate both a Java and an XML version of the constants like so:
Java:
public final class BuildConstants {
public static final boolean ABOOLEAN = true;
public static final String ASTRING = "string";
public static final int ANUMBER = 123;
private BuildConstants() {
throw new AssertionError("No instances.");
}
}XML:
<resources>
<bool name="aboolean">true</bool>
<string name="astring">string</string>
<integer name="anumber">123</integer>
</resources>Alternatively, you can define the constants using a map:
buildConstants {
constants = [
aBoolean : true,
aString : 'string',
aNumber : 123
]
}Or specify just a single constant (similar to buildConfigField):
buildConstants {
constant 'single_constant', 'single_string'
}The default generated file names are BuildConstants.java and build_constants.xml.
You can change them like this:
buildConstants {
javaFileName 'SampleBuildConstants'
xmlFileName 'sample_build_constants'
}Check out the sample project for an example implementation.
Build script snippet for use in all Gradle versions:
buildscript {
repositories {
maven {
url 'https://plugins.gradle.org/m2/'
}
}
dependencies {
classpath 'gradle.plugin.com.jenzz:buildconstants:1.1.0'
}
}
apply plugin: 'com.jenzz.buildconstants'Build script snippet for new, incubating, plugin mechanism introduced in Gradle 2.1:
plugins {
id 'com.jenzz.buildconstants' version '1.1.0'
}This project is licensed under the MIT License.
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