個(gè)人原創(chuàng)葛菇，轉(zhuǎn)載請(qǐng)注明出處：http://www.reibang.com/p/e7049cef9431
If not null
val files = File("Test").listFiles()
println(files?.size)
If not null or else
val files = File("Test").listFiles()
println(files?.size ?: "empty")
If not null and true
if (someObject?.status == true) doThis()
或
someObject?.takeIf{ it.status }?.apply{ doThis() }
If not null and true or else
if (someObject?.status == true) {
doThis()
}else {
doThat()
}
或
someObject?.takeIf{ it.status }?.apply{ doThis() } ?: apply{ doThat() }
if not null 賦值
val objA = ...
val objB = ...
objB.value = objA.value ?: objB.value
if null 賦值
val objA = ...
val objB = ...
objB.value = objB.value ?: objA.value
if null 執(zhí)行一個(gè)語(yǔ)句
val values = ……
val email = values["email"] ?: throw IllegalStateException("Email is missing!")
