KOTLIN somo la 18: string na method zinazotumika kwenye list data type.

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 ...