字符串使用“”包圍起來
使用+進(jìn)行字符串拼接
使用$來進(jìn)行數(shù)字輸出
val fish = 5
"I have $fish"
還可以在字符串中進(jìn)行數(shù)字的數(shù)學(xué)運(yùn)算（$和{}）：
val fish = 5
val plants = 12
"I have ${fish+plants} fish and plants"
布爾運(yùn)算符與其它語言一樣识补，例如==排截，!=等
接下來是判斷（if-else）
val numOfFish=30
val numOfPlants=23
if (numOfFish>numOfPlants) println("good ratio")
else
? ? println("unhealthy ratio")
下面是范圍判斷（..）
val fish=50
if (fish in 1..100) println(fish)
下面是和其它語言的switch一樣的when:
val numOfFish = 50
when(numOfFish){
? ? 0->println("empty tank")
? ? 50->println("full tank")
? ? else->println("perfect")
}
有一道練習(xí)題：
var welcomeMessage ="Hello and welcome to Kotlin"
when (welcomeMessage.length) {
0->println("Nothing to say?")
in1..50->println("Perfect")
else->println("Too long!")
}
結(jié)果應(yīng)該是：Perfect
習(xí)題1：
Create three String variables fortrout,haddock, andsnapper.
Use a String template to print whether you do or don't like to eat these kinds of fish.
官方答案是：
val trout ="trout"
var haddock ="haddock"
var snapper ="snapper"
println("I like to eat $trout and $snapper, but not a big fan of $haddock.")
習(xí)題2：
whenstatements in Kotlin are likecaseorswitchstatements in other languages.
Create awhenstatement with three comparisons:
If the length of thefishNameis 0, print an error message.
If the length is in the range of 3...12, print "Good fish name".
If it's anything else, print "OK fish name".
官方答案是：
when(fishName.length){
0-> println("Fish name cannot be empty")
in 3..12-> println("Good fish name")
else->println("OK fish name")
}
