kotlin一些好用的方法

有趣的kotlin语法

1.数组过虑.

val positives = list.filter { it > 0 }

2.范围的使用

for (i in 1..100) { ... }
for (i in 1 until 100) { ... }
for (x in 2..10 step 2) { ... }
for (x in 10 downTo 1) { ... }
if (x in 1..10) { ... }

3. Read-only list

val list = listOf("a", "b", "c")

4. Read-only map

val map = mapOf("a" to 1, "b" to 2, "c" to 3)

5.访问数组，这个比java访问方便多了

map["key"] = value

6. Extension Functions

fun String.spaceToCamelCase() { ... }
"Convert this to camelcase".spaceToCamelCase()

7. Creating a singleton

object Resource {
    val name = "Name"
}

数组中好用的方法

1. 快捷过来数组中的空元素 filterNotNull()

    val nullableList: List = listOf(1, 2, null, 4)
    val intList: List = nullableList.filterNotNull()
   

参考

kotlin官方文档