如何设计一个复杂的类，其中包含一些类，以便将来在Kotlin中轻松扩展? [英] How to design a complex class which incude some classes to make expansion easily in future in Kotlin?

问题描述

我是Kotlin的初学者，我使用代码A定义复杂的类MDetail，并使用代码B创建对象aMDetail1，它可以正常工作.

I'm a beginner of Kotlin, I use Code A to define a complex class MDetail, and use Code B to create a object aMDetail1, it can work.

但是数据结构很难扩展，如果像代码C那样在MDetail中包含新的数据类(例如ScreenDef)，则必须重写所有旧代码.

But the data construction is too bad to expand, if I include a new data class such as ScreenDef in MDetail just like Code C, all old code have to be rewriten.

对于包含某些类的复杂类，是否有良好的数据构造?希望将来数据结构可以轻松扩展！

Is there a good data construction for a complex class which include some classes ? I hope to the data construction can be expansion easily in future!

代码A

data class BluetoothDef(val Status:Boolean=false)
data class WiFiDef(val Name:String, val Status:Boolean=false)

data class MDetail (
        val _id: Long,
        val bluetooth: BluetoothDef,
        val wiFi:WiFiDef
)

代码B

var mBluetoothDef1= BluetoothDef()
var mWiFiDef1= WiFiHelper(this).getWiFiDefFromSystem()
var aMDetail1= MDetail(7L,mBluetoothDef1,mWiFiDef1)

代码C

data class BluetoothDef(val Status:Boolean=false)
data class WiFiDef(val Name:String, val Status:Boolean=false)
data class ScreenDef(val Name:String, val size:Long)
... 

data class MDetail (
        val _id: Long,
        val bluetooth: BluetoothDef,
        val wiFi:WiFiDef
        val aScreenDef:ScreenDef        
        ...
)

以下代码基于 s1m0nw1 所说的内容，我认为将来很容易扩展.谢谢！

The following code is based what s1m0nw1 said, I think it's easy to extend for future. Thanks!

还有其他更好的方法吗?

Is there other more better way?

版本1代码

interface DeviceDef

data class BluetoothDef(val Status: Boolean = false) : DeviceDef
data class WiFiDef(val Name: String, val Status: Boolean = false) : DeviceDef
data class ScreenDef(val Name: String, val size: Long) : DeviceDef

class MDetail(val _id: Long, val devices: MutableList<DeviceDef>) {
    inline fun <reified T> getDevice(): T {
        return devices.filterIsInstance(T::class.java).first()
    }
}

class UIMain : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.layout_main)

        val btD = BluetoothDef(true)
        val wfD = WiFiDef("MyWifi")
        val xSc = ScreenDef("MyScreen", 1)
        val m = MDetail(7L, mutableListOf(btD, wfD, xSc))


        handleBluetoothDef(m.getDevice<BluetoothDef>())
        handleWiFiDef(m.getDevice<WiFiDef>())
        handleScreenDef(m.getDevice<ScreenDef>())
    }

    fun handleBluetoothDef(mBluetoothDef:BluetoothDef){ }    
    fun handleWiFiDef(mWiFiDef:WiFiDef){ }    
    fun handleScreenDef(mScreenDef:ScreenDef){ }
}

第2版代码(扩展)

interface DeviceDef

data class BluetoothDef(val Status: Boolean = false) : DeviceDef
data class WiFiDef(val Name: String, val Status: Boolean = false) : DeviceDef
data class ScreenDef(val Name: String, val size: Long) : DeviceDef

data class TimeLine(val Name: String): DeviceDef  //Extend

class MDetail(val _id: Long, val devices: MutableList<DeviceDef>) {
    inline fun <reified T> getDevice(): T {
        return devices.filterIsInstance(T::class.java).first()
    }
}

class UIMain : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.layout_main)

        val btD = BluetoothDef(true)
        val wfD = WiFiDef("MyWifi")
        val xSc = ScreenDef("MyScreen", 1)

        val aTe = TimeLine("MyTimeline")  //Extend

        val m = MDetail(7L, mutableListOf(btD, wfD, xSc,aTe)) //Modified


        handleBluetoothDef(m.getDevice<BluetoothDef>())
        handleWiFiDef(m.getDevice<WiFiDef>())
        handleScreenDef(m.getDevice<ScreenDef>())

        handleTimeLine(m.getDevice<TimeLine>()) //Extend
    }

    fun handleBluetoothDef(mBluetoothDef:BluetoothDef){}    
    fun handleWiFiDef(mWiFiDef:WiFiDef){ }    
    fun handleScreenDef(mScreenDef:ScreenDef){ }           
    fun handleTimeLine(mTimeLine:TimeLine){}  //Extend

帮助

我必须用开放类替换接口，因为我无法从json字符串GSON中反序列化MDetail对象.

I have to replace interface with open class because I can't unserialize MDetail object from json string GSON.

但是有趣的inline fun <reified T> getDevice(): T{ }无法返回正确的结果，我该如何修改?谢谢！

but the fun inline fun <reified T> getDevice(): T{ } can't return correct result, how can I modify? Thanks!

open class DeviceDef

data class BluetoothDef(val status:Boolean=false):  DeviceDef()
data class WiFiDef(val name:String, val status:Boolean=false) : DeviceDef()

data class MDetail(val _id: Long, val deviceList: MutableList<DeviceDef>)
{
    inline fun <reified T> getDevice(): T {        
        return deviceList.filterIsInstance(T::class.java).first()
    }
}

推荐答案

我建议您执行以下操作:您的设备(Wifi，蓝牙等)应通过接口(至少作为标记)进行抽象，可以是名为DeviceDef.

I suggest to do the following: Your units (Wifi, Bluetooth etc.) should be abstracted by an interface (at least as a marker), which could be named DeviceDef.

interface DeviceDef
data class BluetoothDef(val Status: Boolean = false) : DeviceDef
data class WiFiDef(val Name: String, val Status: Boolean = false) : DeviceDef
data class ScreenDef(val Name: String, val size: Long) : DeviceDef 

可以使用这些设备的变量列表实例化MDetail类，以便在添加新设备(例如ScreenDef)时无需修改:

The MDetail class can be instantiated with a variable list of these devices, so that no modifications are needed when new devices, such as ScreenDef, are added:

class MDetail(val _id: Long, val devices: List<DeviceDef>)

在MDetail内，您可以提供一种过滤这些设备的方法:

Inside MDetail, you can provide a method for filtering these devices:

class MDetail(val _id: Long, val devices: List<DeviceDef>) {

    inline fun <reified T> getDevice(): T {
        return devices.filterIsInstance(T::class.java).first()
    }
}

现在，使用WifiDef非常简单，例如:

Now, it's pretty simple to work with the WifiDef for example:

fun main(args: Array<String>) {
    val btD = BluetoothDef()
    val wfD = WiFiDef("")
    val m = MDetail(7L, listOf(btD, wfD, ScreenDef("", 1)))
    println(m.getDevice<WiFiDef>())
}

我希望这会有所帮助.如果不是，则可能有必要提供有关MDetail应该如何工作的更多详细信息.

I hope this helps. If not, it might be necessary that you provide more details on how MDetail is supposed to work.

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