A gradle function to read properties from a file

read_properties.gradle

def getProperty(String filename, String propName) {
    def propsFile = rootProject.file(filename)
    if (propsFile.exists()) {
        def props = new Properties()
        props.load(new FileInputStream(propsFile))
        if (props[propName] != null) {
            return props[propName]
        } else {
            print("No such property " + propName + " in file " + filename)
        }
    } else {
        print(filename + " does not exist!")
    }
}

Sample usage inside an android's app module gradle file

android {
    defaultConfig {
        .....
        buildConfigField "String", "NEWS_API_KEY", "\"${getProperty("local.properties", "news_api_key")}\""
        .....
    }
}

def getProperty(String filename, String propName) {
    def propsFile = rootProject.file(filename)
    if (propsFile.exists()) {
        def props = new Properties()
        props.load(new FileInputStream(propsFile))
        if (props[propName] != null) {
            return props[propName]
        } else {
            print("No such property " + propName + " in file " + filename)
        }
    } else {
        print(filename + " does not exist!")
    }
}