CODEWITHSUNDEEP
androidkotlin
Aarth Tandel
Aarth Tandel

Reputation: 1009

Clone a object in kotlin

I have migrated my application from Java to Kotlin. In Java, the copying was working just fine. However, when migrated to Kotline it was not working. After that, I came to know about copy method in Kotlin

I have tied this, but it seems I am doing something wrong.

Here is my function : 

fun updateSwitchState(deviceName: String, switchNumber: Int): AuraSwitch? {
    val singleDevice = Switch()
    for (c in FourNodeDevice) {
        if (deviceName == c.name) {
            val copyDevice : SwitchClone = SwitchClone(c.state, c.name)
            val state = copyDevice.copy(state = copyDevice.state)
            state.updateState(switchNumber)
            singleDevice.state = state.state
            return singleDevice
        }
    }
    return null
}

Whenever I change data in object state in updateState Method the value in object c also gets changed. Any help will be useful

Upvotes: 0

Views: 8728

Answers (3)

Xenolion
Xenolion

Reputation: 12725

For Kotlin when using the Kotlin Data Class data class you get a function called copy() for you. But If your Class is not a Data Class and your project has Gson and you want to copy the whole object ( probably edit after getting it ), Then if all those conditions are true then this is a solution. This is also a DeepCopy. ( For a data Class you can use the function copy()).

Then if you are using Gson in your project. Add the function copy():

class YourClass () {

// Your class other stuffs here

  fun copy(): YourClass { //Get another instance of YourClass with the values like this!
      val json = Gson().toJson(this)
      return Gson().fromJson(json, YourClass::class.java)
  }
}

If you want to install Gson then get the latest version here.

Upvotes: 1

Aarth Tandel
Aarth Tandel

Reputation: 1009

The copy() did not solve my purpose. However clone() did. I added the following line in my code and it worked as I desired.

val state = c.states.clone()

Upvotes: -1

Pawel
Pawel

Reputation: 17268

You never create a copy of a state object.

This call creates another SwitchClone with values identical to copyDevice itself.

val state = copyDevice.copy(state = copyDevice.state)

copy() only creates a shallow copy, which means all of your objects, in that case c, copyDevice and state point to the same c.state.

You need to explicitly create a deep copy (depending on what properties are mutable) of state object and assign it to copyDevice.state field.

Upvotes: 1

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