CODEWITHSUNDEEP
javaandroidarrayskotlin
Arsen Saruhanyan
Arsen Saruhanyan

Reputation: 173

ArrayList.filter won't work

So, I have this code for Android:

parkingList.removeIf { parking-> parking.city != pr.city }
parkingList.removeIf { parking-> parking.price.toDouble() <= pr.priceFrom }
parkingList.removeIf { parking-> parking.price.toDouble() >= pr.priceTo }
parkingList.removeIf { parking-> parking.daysBusy.contains(daysSet.split("|").toString()) }

This is code I have right now. I can't use anything else, because when I'm using filter to my arraylist parkingList, it won't work. And I don't know why. This is how I use it:

parkingList.filter { parking-> parking.city === pr.city }
parkingList.filter { parking-> parking.price.toDouble() >= pr.priceFrom }
parkingList.filter { parking-> parking.price.toDouble() <= pr.priceTo }
parkingList.filter { parking-> !parking.daysBusy.contains(daysSet.split("|").toString()) }

But for some reason it won't work. P.S. I need only API19, so, this is the reason, why I must use only filter (Or no?)

CODE:

val filteredList = parkingList.filter { parking-> parking.city === pr.city
        parking.price.toDouble() >= pr.priceFrom
        parking.price.toDouble() <= pr.priceTo
        !parking.daysBusy.contains(daysSet.split("|").toString())
    } as ArrayList

filteredList.forEach { println(it) }
val adapter = CustomAdapter(filteredList)

Upvotes: 4

Views: 275

Answers (2)

SRS
SRS

Reputation: 1

You can use this code to filter out the element from array, by using this code:

    var day: List = arrayListOf("Sunday", "Monday", "Tuesday","Wednesday")


// to get the result as list


      var dayList: List = day.filter { s -> s == "Monday" }

// to get a a string

    var selectedDay: String = day.filter { s -> s == "`enter code here`Monday" }.single() 


     println("the value  is $dayList")
println("the value is $selectedDay")

Upvotes: 0

lelloman
lelloman

Reputation: 14173

removeIf will envetually remove elements from the list on which you call it, it works in-place.

val originalList = arrayListOf(1,2,3,4)
originalList.removeIf { it % 2 == 0 }
// originalList.size is 2

filter on the other hand, will return a new list, so you need to use the returned value.

val originalList = listOf(1,2,3,4)
val filteredList = originalList.filter { it % 2 == 0 }
// originalList.size is 4
// filteredList.size is 2

Also, when you check for equality with parking.city === pr.city, that will return true only if parking.city and pr.city are the same object, it will return false even if the 2 objects have equal values, that is, if equals(Any) returns true

update

In your code you have 4 boolean expressions but only the last one is returned, you need to chain them with an operator, I added && as an example but you need adjust that based on your business logic

filter { parking ->
    parking.city === pr.city &&
    parking.price.toDouble() >= pr.priceFrom &&
    parking.price.toDouble() <= pr.priceTo &&
    !parking.daysBusy.contains(daysSet.split("|").toString())
}

For instance, if you try to filter with

.filter {
    false
    true
}

All elements will be kept be cause the first false is going to be completely ignored, if you instead do

.filter {
    false &&
    true
}

The filtered list will have 0 elements because the filtering expression is now false && true

Upvotes: 5

Related Questions