📅  最后修改于: 2021-01-05 07:44:03             🧑  作者: Mango
Kotlin ArrayList类用于创建动态数组。这意味着可以根据需要增加或减少ArrayList类的大小。 ArrayList类提供读取和写入功能。
Kotlin ArrayList类遵循插入顺序的顺序。 ArrayList类是不同步的,它可能包含重复的元素。 ArrayList类的元素是按索引工作的,因此可以随机访问。
Constructor | Description |
---|---|
ArrayList |
It is used to create an empty ArrayList |
ArrayList(capacity: Int) | It is used to create an ArrayList of specified capacity. |
ArrayList(elements: Collection |
It is used to create an ArrayList filled from the elements of collection. |
Function | Description |
---|---|
open fun add(element: E): Boolean | It is used to add the specific element into the collection. |
open fun add(index: Int, element: E) | It is used to insert an element at specific index. |
open fun addAll(elements: Collection |
It is used to add all the elements in the specified collection to current collection. |
open fun addAll(index: Int, elements: Collection |
It is used to add all the elements of specified collection into the current list at the specified index. |
open fun clear() | It is used to removes all elements from the collection. |
open fun get(index: Int): E | It is used to return the element at specified index in the list. |
open fun indexOf(element: E): Int | It is used to return the index of first occurrence of specified element in the list or return -1 if the specified element in not present in the list. |
open fun lastIndexOf(element: E): Int | It is used to return the last occurrence of given element from the list or it returns -1 if the given element is not present in the list. |
open fun remove(element: E): Boolean | It is used to remove a single instance of the specific element from current collection, if it is available. |
open fun removeAt(index: Int): E | It is used to remove the specific index element from the list. |
open fun removeRange(startIndex: Int, endIndex: Int) | Its remove the range of elements starting from startIndex to endIndex in which endIndex is not includes. |
open fun set(index: Int, element: E): E | It is used to replaces the element from the specified position from current list with the specified element. |
open fun toArray(): Array |
It is used to return new array of type Array |
open fun toString(): String | It is used to returns a string representation of the object. |
fun trimToSize() | It does nothing in this ArrayList implementation. |
让我们创建一个简单的ArrayList类示例示例,该示例使用String的空ArrayList定义并稍后添加元素。
fun main(args: Array){
val arrayList = ArrayList()//Creating an empty arraylist
arrayList.add("Ajay")//Adding object in arraylist
arrayList.add("Vijay")
arrayList.add("Prakash")
arrayList.add("Rohan")
arrayList.add("Vijay")
println(".......print ArrayList.......")
for (i in arrayList) {
println(i)
}
}
输出:
......print ArrayList......
Ajay
Vijay
Prakash
Rohan
Vijay
让我们创建一个具有初始容量的ArrayList类。 ArrayList类的容量不是固定的,以后可以根据需要在程序中进行更改。
fun main(args: Array){
val arrayList1 = ArrayList(5)
arrayList1.add("Ajay")//Adding object in arraylist
arrayList1.add("Vijay")
arrayList1.add("Prakash")
arrayList1.add("Rohan")
arrayList1.add("Vijay")
println(".......print ArrayList1......")
for (i in arrayList1) {
println(i)
}
println("size of arrayList1 = "+arrayList1.size)
val arrayList2 = ArrayList(5)
arrayList2.add(14)
arrayList2.add(20)
arrayList2.add(80)
println("......print ArrayList2......")
for (i in arrayList2) {
println(i)
}
println("size of arrayList2 = "+arrayList2.size)
}
输出:
.......print ArrayList1......
Ajay
Vijay
Prakash
Rohan
Vijay
size of arrayList1 = 5
......print ArrayList2......
14
20
80
size of arrayList2 = 3
Kotlin ArratList类中的元素也可以使用其他集合添加。对于ArrayList类中的更多特定类,它由其泛型类型声明。 ArrayList类的元素也可以使用iterator()函数遍历。例如:
fun main(args: Array){
val arrayList: ArrayList = ArrayList(5)
var list: MutableList = mutableListOf()
list.add("Ajay")
list.add("Vijay")
list.add("Prakash")
arrayList.addAll(list)
println("......print ArrayList......")
val itr = arrayList.iterator()
while(itr.hasNext()) {
println(itr.next())
}
println("size of arrayList = "+arrayList.size)
}
输出:
.......print ArrayList.......
Ajay
Vijay
Prakash
size of arrayList = 3
ArrayList类的get()函数用于检索给定指定索引处存在的元素。例如:
fun main(args: Array){
val arrayList: ArrayList = ArrayList(5)
arrayList.add("Ajay")
arrayList.add("Vijay")
arrayList.add("Prakash")
arrayList.add("Rohan")
arrayList.add("Vijay")
println(".......print ArrayList.......")
for (i in arrayList) {
println(i)
}
println(".......arrayList.get(2).......")
println( arrayList.get(2))
}
输出:
.......print ArrayList.......
Ajay
Vijay
Prakash
Rohan
Vijay
.......arrayList.get(2).......
Prakash
ArrayList类的set()函数用于在给定索引处设置给定元素,如果在给定索引处存在任何元素,则将其替换。例如:
fun main(args: Array){
val arrayList: ArrayList = ArrayList(5)
arrayList.add("Ajay")
arrayList.add("Vijay")
arrayList.add("Prakash")
arrayList.add("Rohan")
arrayList.add("Vijay")
println(".......print ArrayList.......")
for (i in arrayList) {
println(i)
}
println(".......arrayList.set(2,\"Ashu\").......")
arrayList.set(2,"Ashu")
println(".......print ArrayList.......")
for (i in arrayList) {
println(i)
}
}
输出:
.......print ArrayList.......
Ajay
Vijay
Prakash
Rohan
Vijay
.......arrayList.set(2,"Ashu").......
.......print ArrayList.......
Ajay
Vijay
Ashu
Rohan
Vijay
ArrayList类的indexOf()函数用于检索第一次出现的元素的索引值,如果指定的元素不在列表中,则返回-1。例如:
fun main(args: Array){
val arrayList: ArrayList = ArrayList(5)
arrayList.add("Ajay")
arrayList.add("Vijay")
arrayList.add("Prakash")
arrayList.add("Rohan")
arrayList.add("Vijay")
println(".......print ArrayList.......")
for (i in arrayList) {
println(i)
}
println(".......arrayList.indexOf(\"Vijay\").......")
println(arrayList.indexOf("Vijay"))
}
输出:
.......print ArrayList.......
Ajay
Vijay
Prakash
Rohan
Vijay
.......arrayList.indexOf("Vijay").......
1
ArrayList类的lastindexOf()函数用于检索元素的最后一次出现的索引值,如果指定的元素不在列表中,则返回-1。例如:
fun main(args: Array){
val arrayList: ArrayList = ArrayList(5)
arrayList.add("Ajay")
arrayList.add("Vijay")
arrayList.add("Prakash")
arrayList.add("Rohan")
arrayList.add("Vijay")
println(".......print ArrayList.......")
for (i in arrayList) {
println(i)
}
println(".......arrayList.lastIndexOf(\"Vijay\").......")
println(arrayList.lastIndexOf("Vijay"))
}
输出:
.......print ArrayList.......
Ajay
Vijay
Prakash
Rohan
Vijay
.......arrayList.lastIndexOf("Vijay").......
4
ArrayList类的remove()函数用于删除列表中首次出现的元素。例如:
fun main(args: Array){
val arrayList: ArrayList = ArrayList(5)
arrayList.add("Ajay")
arrayList.add("Vijay")
arrayList.add("Prakash")
arrayList.add("Rohan")
arrayList.add("Vijay")
println(".......print ArrayList.......")
for (i in arrayList) {
println(i)
}
println(".......arrayList.remove(\"Vijay\").......")
arrayList.remove("Vijay")
for (i in arrayList) {
println(i)
}
}
输出:
.......print ArrayList.......
Ajay
Vijay
Prakash
Rohan
Vijay
.......arrayList.remove("Vijay").......
Ajay
Prakash
Rohan
Vijay
ArrayList类的removeAt()函数用于从列表中删除指定索引的元素。例如:
fun main(args: Array){
val arrayList: ArrayList = ArrayList(5)
arrayList.add("Ajay")
arrayList.add("Vijay")
arrayList.add("Prakash")
arrayList.add("Rohan")
arrayList.add("Vijay")
println(".......print ArrayList.......")
for (i in arrayList) {
println(i)
}
println(".......arrayList.remove(3).......")
arrayList.removeAt(3)
for (i in arrayList) {
println(i)
}
}
输出:
.......print ArrayList.......
Ajay
Vijay
Prakash
Rohan
Vijay
.......arrayList.remove(3).......
Ajay
Vijay
Prakash
Vijay
ArrayList类的clear()函数用于删除(清除)列表的所有元素。例如:
fun main(args: Array){
val arrayList: ArrayList = ArrayList(5)
arrayList.add("Ajay")
arrayList.add("Vijay")
arrayList.add("Prakash")
arrayList.add("Rohan")
arrayList.add("Vijay")
println(".......print ArrayList.......")
for (i in arrayList) {
println(i)
}
println(".......arrayList.clear().......")
arrayList.clear()
for (i in arrayList) {
println(i)
}
println(".......arrayList.......")
println(arrayList)
}
输出:
.......print ArrayList.......
Ajay
Vijay
Prakash
Rohan
Vijay
.......arrayList.clear().......
.......arrayList.......
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