Sometimes you need to send adb commands to all connected devices/emulators from your gradle script. This function will do that for you. Create a closure that takes a serial id (string) as an argument and call sendToDevices().

sendToDevices.gradle

/*
  Example:
  task tapPowerButton() {
    group = 'device'
    description = 'Tap the power button on all devices/emulators'
    doLast {
        def action = { serial ->
            def adb = android.getAdbExe().toString()
            exec {
                commandLine "$adb -s $serial shell input keyevent 26".split(' ')
            }
        }
        sendToDevices(action)
    }
  }
*/

/**
 * Call closure for each connected device or emulator.
 * Any exception thrown by the closure will be collected and the *first* one will be thrown
 * once the closure has been called for all devices/emulators.
 * @param closure the serialid
 */
def sendToDevices(def closure) {
    def adb = android.getAdbExe().toString()
    def output = "${adb} devices".execute().text
    Throwable caughtThrowable = null
    output.eachLine { line ->
        line = line.toLowerCase()
        def processLine = line.contains("emulator") || (line.contains("device") && !line.contains("devices"))
        if (processLine) {
            def serial = line.split().first()
            println("Calling closure with serial '${serial}'")
            try {
                closure(serial)
            } catch (Throwable t) {
                // Do not crash if we get an exception from one device
                // Store the throwable so we can rethrow it at the end
                if (caughtThrowable == null) {
                    caughtThrowable = t
                }
                t.printStackTrace()
            }
        }
    }
    if (caughtThrowable != null) {
        throw caughtThrowable
    }
}