Kotlin let apply run with also takeif

Let

lambda后面会有it，返回最后一行的执行结果 (Boolean)

val result1: Boolean = "nihao".let { it.length >= 10
}

apply

lambda后面是this，支持隐式调用，即不需要对象来点，返回this执行后的 this自己 (String)

val result2: String = "nihao".apply {length >= 10
}

run

lambda后面是this，返回最后一行的执行结果 (Boolean)

val result3: Boolean = "nihao".run {length >= 10
}

with

和Run一样，只是由 对象.run 变成了 with(对象)

val result4: Boolean = with("nihao") {length >=10
}

also

also后面是it，返回it自己 (string)，和apply一样，只不过apply是this

val result5: String = "nihao".also { it.length >= 10
}

takeif

如果takeif后面是true 返回自己，否则返回null

val result6: String? = "nihao".takeIf {it.length >= 10}?.capitalize()
}