I have a list of objects like this:
[
{
"Price": 2100000,
"Id": "5f53787e871ebc4bda455927"
},
{
"Price": 2089000,
"Id": "5f7da4ef7a0ad2ed730416f8"
},
{
"Price": 0,
"Id": "5f82b1189c333dab0b1ce3c5"
}
]
How can I sort this list by price value of objects and then pass it to my adapter?
If you have an object like this:
class YourClass(
val price: Int,
val id: String
)
You can sort by price in two ways:
Mutable
val yourMutableList: MutableList<YourClass> = mutableListOf()
yourMutableList.sortBy { it.price }
// now yourMutableList is sorted itself
Not mutable
val yourList: List<YourClass> = listOf()
val yourSortedList: List<YourClass> = yourList.sortedBy { it.price }
As you can see, in the second sample, you have to save the result in a new list. Because List is immutable, therefore it cannot be altered and it is necessary to create a new list.
Happy coding! :)
Here's a very simple example to sort by your choice of order:
class Pizza(
val price: Double
)
val regularSlice = Pizza(price = 2.75)
val extraCheeseSlice = Pizza(price = 3.75)
val pepperoniSlice = Pizza(price = 4.75)
val list = ArrayList<Pizza>()
list.add(extraCheeseSlice)
list.add(pepperoniSlice)
list.add(regularSlice)
This is the same exact list sorted in place:
list.sortBy { it.price } // lowest to highest - result is: regularSlice, extraCheeseSlice, pepperoniSlice
list.sortByDescending { it.price } // highest to lowest - result is: pepperoniSlice, extraCheeseSlice, regularSlice
If you want a new list just use sortedBy:
val newListFromLowestToHighest = list.sortedBy { it.price } // result is: regularSlice, extraCheeseSlice, pepperoniSlice
val newListFromHighestToLowest = list.sortByDescending { it.price } // result is: pepperoniSlice, extraCheeseSlice, regularSlice
Assuming you have a class that represents your elements like this:
data class Element (
val price: Int,
val id: String
)
And given a list of those from your deserializer:
val listOfElements: List<Element> = ...
You can obtain a new list sorted by price as follows:
val sortedByPrice = listOfElements.sortedBy { it.price }
Try it in the Kotlin Playground: https://pl.kotl.in/TBIdxsaoi
