Bridge Design Pattern - Kotlin

BridgeDesignPattern.kt

class BridgeDesignPattern {
    companion object {
        @JvmStatic
        fun main(args: Array<String>) {
            // Send new text message
            val textMessageSender: MessageSender = TextMessageSender()
            val textMessage: Message = TextMessage(textMessageSender)
            textMessage.send()

            // Send new email message
            val emailMessageSender: MessageSender = EmailMessageSender()
            val emailMessage: Message = EmailMessage(emailMessageSender)
            emailMessage.send()
        }
    }
}

/**
 * Base class to send message.
 * [Message] takes [MessageSender] instance as a parameter by following ** Has-A Relationship ** and ** Composition **.
 *
 * @param sender [MessageSender] instance to send message.
 */
abstract class Message(internal val sender: MessageSender) {
    abstract fun send()
}

/**
 * Impl of [Message] to send Text Message.
 *
 * @param messageSender, [MessageSender] instance to send message.
 */
class TextMessage(messageSender: MessageSender) : Message(messageSender) {
    override fun send() {
        sender.sendMessage()
    }
}

/**
 * Impl of [Message] to send Email Message.
 *
 * @param messageSender, [MessageSender] instance to send message.
 */
class EmailMessage(messageSender: MessageSender) : Message(messageSender) {
    override fun send() {
        sender.sendMessage()
    }
}

/**
 * Base of message sending implementation.
 */
interface MessageSender {
    fun sendMessage()
}

/**
 * Impl of [MessageSender], is responsible to send Text Message.
 */
class TextMessageSender : MessageSender {
    override fun sendMessage() {
        println("TextMessageSender: Sending text message...")
    }
}

/**
 * Impl of [MessageSender], is responsible to send Email Message.
 */
class EmailMessageSender : MessageSender {
    override fun sendMessage() {
        println("EmailMessageSender: Sending email message...")
    }
}