Kotlin基本

range 表达式

val number = 148
if (number in 10..59) {
    println("fail")
} else if (number in 0..9) {
    println("too bad")
} else if (number in 60..100) {
    println("very well")
} else {
    println("God")
}

when 表达式

    val day = 5
    val dayinfo = when(day) {
        1 -> "Today is Monday"
        2 -> "Today is Tuesday"
        3 -> "Today is Wednesday"
        else -> {
            println("pig pig day, i don't know")
        }
    }
    println(dayinfo)

字符串模板

val park ="Yellowstone National Park"
val time = 6

println("Today, I go to ${park} and stay there ${time} hours")

val isLogin = false
println("server response: ${if(isLogin) "Congratulations, Login success" else "Opps, Login fail"}")

函数
函数参数，可以有默认值。借鉴了C++的一些特性。

fun main(args: Array<String>) {
    method1("scott", 20)
    method2("Jetty")
}

private fun method1(name: String, age: Int) {
    println(name)
    println(age)
}

private fun method2(name: String = "lisha", age: Int = 20) {
    println(name)
    println(age)
}

具名函数

fun main(args: Array<String>) {
    loinAction(age = 99, usernum = "123", userpwd = "deay", username = "Kitty", phonenumber = "13411211111")
}

private fun loinAction(username: String, userpwd: String, phonenumber: String, age: Int, usernum: String) {
    
}

Unit 函数（类似java的void类型的函数）

Nothing类型，TODO(“xxxx”) 相当于Java throw，抛出异常

反引号的作用，在Kotlin中调用Java类中的函数，而java中的函数名，恰好是Kotlin的关键字时，需要对函数名加反引号调用