Groovy increment versionCode in gradle.properties

increment.groovy

// increment the versionCode in the build.properties file
def incrementBuildPropertiesVersion() {
  // load build.properties file
  def buildProps = new Properties()
  def buildPropsFile = new File('android/build.properties')
  buildProps.load(buildPropsFile.newDataInputStream())

  // get old version code from properties file
  def oldVersionCode = buildProps.getProperty('VERSION_CODE')
  def newVersionCode = Integer.parseInt(oldVersionCode) + 1
  println "Incrementing versionCode from ${oldVersionCode} to ${newVersionCode}"
  buildProps.setProperty('VERSION_CODE', "${newVersionCode}")

  // write properties file back to system
  println "Writing build.properties"
  buildProps.store(buildPropsFile.newWriter(), null)
}