一起来学Kotlin:概念:1. Kotlin ArrayListOf 的使用案例
概念:1. Kotlin ArrayListOf 的使用案例
arrayList()
是 Kotlin
ArrayList
类的函数,用于创建一个新的 ArrayList
。 ArrayList
是可变的(mutable),这意味着我们可以修改 ArrayList
的内容。
文章目录
- 概念:1. Kotlin ArrayListOf 的使用案例
- @[TOC](文章目录)
- 例子1:new empty ArrayList
- 例子2:new ArrayList with String elements
- 例子3:new ArrayList with elements of any data type
- 例子4:add new element into ArrayList
- 例子5:clear element of ArrayList
- 例子6:contains/containsAll
文章目录
- 概念:1. Kotlin ArrayListOf 的使用案例
- @[TOC](文章目录)
- 例子1:new empty ArrayList
- 例子2:new ArrayList with String elements
- 例子3:new ArrayList with elements of any data type
- 例子4:add new element into ArrayList
- 例子5:clear element of ArrayList
- 例子6:contains/containsAll
例子1:new empty ArrayList
var arrList = arrayListOf<String>()
println(arrList.isEmpty()) // true
println("ArrayList : ${arrList}") // ArrayList : []
例子2:new ArrayList with String elements
var arrList = arrayListOf<String>("Java", "Python", "JavaScript")
println(arrList.isEmpty()) // false
println("ArrayList : ${arrList}") // ArrayList : [Java, Python, JavaScript]
例子3:new ArrayList with elements of any data type
var arrList = arrayListOf<Any>(1, 2, 3, "GeeksforGeeks", 100.0)
println(arrList.isEmpty()) // false
println("ArrayList : ${arrList}") // ArrayList : [1, 2, 3, GeeksforGeeks, 100.0]
println(arrList.size) // 5
例子4:add new element into ArrayList
val list = arrayListOf<Int>()
println("list.isEmpty() is ${list.isEmpty()}") // true
list.addAll(listOf(1, 2, 3))
println(list) // [1, 2, 3]
list += listOf(4, 5)
println(list) // [1, 2, 3, 4, 5]
list.add(0, 1)
println(list) // [1, 1, 2, 3, 4, 5],即,第一个位置添加1
例子5:clear element of ArrayList
var arrList = arrayListOf<String>("Java", "Kotlin");
println(arrList); // [Java, Kotlin]
arrList.clear();
println(arrList); // []
var arrList = arrayListOf<String>("Java", "Kotlin", "Python", "Kotlin");
println(arrList.removeAt(3)); // Kotlin
println(arrList); // [Java, Kotlin, Python]
例子6:contains/containsAll
var arrList = arrayListOf<String>("Java", "Kotlin");
println(arrList.contains("Kotlin")); // true
var arrList = arrayListOf<String>("Java", "Kotlin", "Python", "JavaScript");
var checkList = listOf("Python", "Java");
println(arrList.containsAll(checkList)); // true