Kotlin - Use an object of ListOf List as an element in another Object w/ListOf List-CodePudding

I have a class that describes an object such that:

data class Item(
    var productName: String = "",
    var productId: String = "", 
    var productDesc: String = "", 
    var productPrice: String = ""
)

and an object which holds a variable of a ListOf Item(s):

object Items {
    var myItems = listOf<Item>(

        Item(
          productName:  "Item #1",
          productId: "com.example.website.products.item1",
          productDesc: "This is a description for Item #1",
          productPrice: "$5.99"
         ),

        Item(
          productName:  "Item #2",
          productId: "com.example.website.products.item2",
          productDesc: "This is a description for Item #2",
          productPrice: "$0.99"
         )

    )
}

This works great, I can access the List with:

for (myItem in Items.myItems) {
  //do this
}

or other similar methods.

What I have run into lately is that the list of items has grown too big and the file is becoming too large for AndroidStudio to process.

I would like to be able to make a few separate objects and then merge them into one object with a reference to each object. Not sure I am explaining this correctly, but this is what I imagine it would look like:

data class Item(
    var productName: String = "",
    var productId: String = "", 
    var productDesc: String = "", 
    var productPrice: String = ""
)

//Master Object with references to "sub" objects below:
object Items {
   var myItems = listOf<Item>(
      ItemsForUSA.myItems,
      ItemsForCAN.myItems
   )
}


//Object #1
object ItemsForUSA {
    var myItems = listOf<Item>(

        Item(
          productName:  "Item #1",
          productId: "com.example.website.products.item1",
          productDesc: "This is a description for Item #1",
          productPrice: "$5.99"
         ),

        Item(
          productName:  "Item #2",
          productId: "com.example.website.products.item2",
          productDesc: "This is a description for Item #2",
          productPrice: "$0.99"
         )

    )
}


//Object #2
object ItemsForCAN {
    var myItems = listOf<Item>(

        Item(
          productName:  "Item #3",
          productId: "com.example.website.products.item3",
          productDesc: "This is a description for Item #3",
          productPrice: "$2.99"
         ),

        Item(
          productName:  "Item #4",
          productId: "com.example.website.products.item4",
          productDesc: "This is a description for Item #4",
          productPrice: "$1.99"
         )

    )
}

This way, I could reference Items.myItems and get everything in both ItemsForUSA and ItemsForCAN etc..

Is this possible?

Any insight appreciated.

CodePudding user response：

You can combine collections with a.plus(b) - since that's an operator, you can just do a b.

Just bear in mind that this produces a new collection, so if you're under memory constraints, this isn't the way to go! And you'd want something like a database instead, so you can select or stream data as needed instead of holding it all in memory.

If it's just a case of your file having a huge number of lines and making Android Studio choke, you might want to consider storing your data in a text file instead (e.g. a CSV file) and place it in assets. Then you can read from that file at runtime and parse it into Items for your list, or use it to initialise a database, etc. It'll be way easier (and more performant) to work with as a plain text file too.

(You're working with Lists by the way, not Arrays! They're not the same thing - there can be some overlap in how you interact with them though, plus is defined for both)