CODESAMPLE

Bridge - Kotlin

Bridge Kotlin

The Bridge pattern is a structural design pattern that lets you split one or several interfaces from their implementation(s), allowing you to vary them independently. It’s beneficial when you have a class that can be configured with different abstractions or implementations without causing tight coupling.

This Kotlin example implements a Bridge with a Device interface (the abstraction) and concrete RemoteControl and DirectControl implementing it. A PowerSupply interface represents the implementation, with Battery and ACAdapter as concrete implementations. The DeviceImpl class bridges the Device and PowerSupply interfaces, allowing different device control methods to work with different power sources without modification. This leverages Kotlin’s interface and class features for a clean, decoupled design, fitting its emphasis on conciseness and readability.

// Abstraction
interface Device {
    fun control(): String
    fun setPowerSupply(powerSupply: PowerSupply)
}

// Refined Abstraction
class RemoteControl(private var powerSupply: PowerSupply) : Device {
    override fun control(): String = "Remote Control: ${powerSupply.powerOn()}"
    override fun setPowerSupply(powerSupply: PowerSupply) {
        this.powerSupply = powerSupply
    }
}

class DirectControl(private var powerSupply: PowerSupply) : Device {
    override fun control(): String = "Direct Control: ${powerSupply.powerOn()}"
    override fun setPowerSupply(powerSupply: PowerSupply) {
        this.powerSupply = powerSupply
    }
}

// Implementation
interface PowerSupply {
    fun powerOn(): String
}

// Concrete Implementations
class Battery : PowerSupply {
    override fun powerOn(): String = "Powered by Battery"
}

class ACAdapter : PowerSupply {
    override fun powerOn(): String = "Powered by AC Adapter"
}

// Bridge
class DeviceImpl(device: Device) {
    private var device: Device

    init {
        this.device = device
    }

    fun operate(): String {
        return device.control()
    }
}

fun main() {
    val battery = Battery()
    val acAdapter = ACAdapter()

    val remoteControl = RemoteControl(battery)
    val directControl = DirectControl(acAdapter)

    val remoteDevice = DeviceImpl(remoteControl)
    val directDevice = DeviceImpl(directControl)

    println(remoteDevice.operate()) // Output: Remote Control: Powered by Battery
    remoteControl.setPowerSupply(acAdapter)
    println(remoteDevice.operate()) // Output: Remote Control: Powered by AC Adapter

    println(directDevice.operate()) // Output: Direct Control: Powered by AC Adapter
}