Katika somo hili tutatumia mifano kwenye list yetu hii ['bongoclass', 'facebook', 'google', 'youtube', 'microsoft'].
List properties
Hizi ni sifa ambazo kila list lazima ziwe nazo.
First hii itatuonyesha item ya mwanzo kabisa mwa hiyo list.
fun main() {
val list1 = listOf("bongoclass", "facebook", "google", "youtube", "microsoft")
println(list1.first())
}
Hii itakupa bongoclass
isEmpty hii itupa majibu true kama list haina kitu ama false kama ina kitu.
fun main() {
val list1 = listOf("bongoclass", "facebook", "google", "youtube", "microsoft")
println(list1.isEmpty())
}
Hii itakupa jibu false.
isNotEmpty hii itaangalia kama list haina kitu itatupa jibu true na kama ina kitu itatupa jibu
false.
fun main() {
val list1 = listOf("bongoclass", "facebook", "google", "youtube", "microsoft")
println(list1.isNotEmpty())
}
Hii itakupa jiu true
size hii itaangalia idadi ya item kwenye hiyo list kwa mfano hapo itatupa jibu 5.
fun main() {
val list1 = listOf("bongoclass", "facebook", "google", "youtube", "microsoft")
println(list1.size)
}
Hii itakupa jibu 5
last hii itatuonyesha item ya mwisho.
fun main() {
val list1 = listOf("bongoclass", "facebook", "google", "youtube", "microsoft")
println(list1.last())
}
Hapo itakupa jibu microsoft
reversed hii itapangilia tena list kutoka mwisho kuja mwanzo.
fun main() {
val list1 = listOf("bongoclass", "facebook", "google", "youtube", "microsoft")
println(list1.reversed())
}
single hii itafanya kazi tu kama item kwenye list ni moja, itadisplay item hiyo, kama ni zaidi ya moja haitafanya kazi.
fun main() {
val list1 = listOf("bongoclass", "facebook", "google", "youtube", "microsoft")
println(list1.isNotEmpty())
println(list1.size)
println(list1.last())
println(list1.reversed())
println(list1.singleOrNull())
}
Kuongeza item kwenye list
add() hii hutumika kuongeza item moja mwishoni mwa list.
fun main() {
val list1 = mutableListOf("bongoclass", "facebook", "google", "youtube", "microsoft")
list1.add("github")
println(list1)
}
addAll hii hutumika kuongeza item zaidi ya moja kwenye list.
fun main() {
val list1 = mutableListOf("bongoclass", "facebook", "google", "youtube", "microsoft")
list1.addAll(listOf("github", "instagram", "telegram"))
println(list1)
}
insert hii hutumika kuongeza item kwenye list sehemu unapotaka kwa kutumia index.
fun main() {
val list1 = mutableListOf("bongoclass", "facebook", "google", "youtube", "microsoft")
list1.add(2, "apple")
println(list1)
}
insertAll hii ni sawa na insert ila inaongeza item zaidi ya moja.
fun main() {
val list1 = mutableListOf("bongoclass", "facebook", "google", "youtube", "microsoft")
list1.addAll(2, listOf("apple", "tesla"))
println(list1)
}
Kubadili (update) item kwenye list
Kwa kutumia index.
fun main() {
val list1 = mutableListOf("bongoclass", "facebook", "google", "youtube", "microsoft")
list1[2] = "WhatsApp"
println(list1)
}
replaceRange hii ni kama tulivyoona hapo juu hutumika ku update item kwenye list, ila hii ina update item zaidi ya moja kulingana na range.
fun main() {
val list1 = mutableListOf("bongoclass", "facebook", "google", "youtube", "microsoft")
list1.subList(1, 4).clear()
list1.addAll(1, listOf("whatsapp", "samsung", "techno"))
println(list1)
}
Kuondosha item kwenye list
Remove hii hutumika kuondoa item moja kwenye list.
fun main() {
val list1 = mutableListOf("bongoclass", "facebook", "google", "youtube", "microsoft")
list1.remove("youtube")
println(list1)
}
Hii itakupa [bongoclass, facebook, google, microsoft]
removeAt hii huondoa item moja kwa kuangalia index yake.
fun main() {
val list1 = mutableListOf("bongoclass", "facebook", "google", "youtube", "microsoft")
list1.removeAt(3)
println(list1)
}
Hii itakupa [bongoclass, facebook, google, microsoft]
removeLast hii hutumika kuondoa item ya mwisho.
fun main() {
val list1 = mutableListOf("bongoclass", "facebook", "google", "youtube", "microsoft")
list1.removeAt(list1.size - 1)
println(list1)
}
removeRange hii hutumika kuondoa item kwa kuangalia range.
fun main() {
val list1 = mutableListOf("bongoclass", "facebook", "google", "youtube", "microsoft")
list1.subList(1, 4).clear()
println(list1)
}
Kufanya iteration kwa kutumia forEach
Kwa kutumia forEach unaweza kuifanyia kazi kila item moja katika list. Hii ni njia ya kufanya loop kwenye list.
fun main() {
val list1 = listOf("bongoclass", "facebook", "google", "youtube", "microsoft")
list1.forEachIndexed { index, element ->
println("$index: $element")
}
}
fun main() {
val list1 = listOf("bongoclass", "facebook", "google", "youtube", "microsoft")
list1.forEach { element ->
println("Jina la website: $element")
}
}
import kotlin.math.sqrt
fun main() {
val list1 = listOf(4, 9, 25, 36, 49, 64, 81, 100)
list1.forEach { element ->
println(sqrt(element.toDouble()))
}
}
Mwisho:
Katika somo linalofuata tutakwenda kujifunza method zinazofanya kazi kwenye set kwenye Kotlin.
