CODEWITHSUNDEEP
androidkotlin
Surendar
Surendar

Reputation: 279

Kotlin mutableMap automatically changing in android?

I'm setting kotlin mutable map in my viewModel like this,

// In ViewModel
var mapData= mutableMapOf<Int, String>()

in my fragment i'm referring this map as below,

//In fragment
lateinit var _mapData: MutableMap<Int, String>

// in oncreate View
_mapData[1] = "one"

When i run above code, this _mapData is automatically updated to my viewModel mapData. I don't want that,

Where I'm having real problem is in the below code,

// initiallizing 
if(!_mapData.contains(2)){
_mapData[2] = _mapData[1]
}

//doing some process to get the actual _mapData[2]

_mapData[2] = "Two"

After running the above code my _mapData[1] is also changing to "Two".

What is this behaviour and why is it happening

Upvotes: 0

Views: 454

Answers (1)

xinaiz
xinaiz

Reputation: 7788

Not sure how you assign _mapData from mapData, but if you simply write:

_mapData = viewModel.mapData

then both variables store reference to the same exact map object. Thus, if you change anything via mapData reference, _mapData content will also change (because it's the same object).

If you want to have separate entities of map in viewModel and fragment, you should copy the map:

_mapData = viewModel.mapData.toMutableMap()

Upvotes: 3

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