if表达式的定义
val age = 30 if(age > 18) 1 else 0
if表达式的类型判断
val age = 30 if(age > 18) "adult" else 0
自己判断返回值类型,返回公共类型Any
在scala的命令行可以使用:paste来运行整段代码
scala> :paste // Entering paste mode (ctrl-D to finish) if(age > 18) "adult" else 0 // Exiting paste mode, now interpreting. res12: Any = adult
默认情况下,scala不需要语句终结符,默认每一行作为一条语句
print和println: println多一行换行符
scala> print("hello world") hello world scala> println("hello world") hello world scala>
printf:可以用来字符串格式化
输入语句
scala> scala.io.StdIn.readLine() res24: String = hello scala> val name = scala.io.StdIn.readLine("please your name:") please your name:name: String = helllo scala>
while do循环
scala> var n = 10 n: Int = 10 scala> :paste // Entering paste mode (ctrl-D to finish) while(n > 0) { println(n) n -= 1 } // Exiting paste mode, now interpreting. 10 9 8 7 6 5 4 3 2 1 scala>
scala没有for循环,只能使用简易版for语句
scala> var n = 10; for(i for(i <- 1 until n) println(i) // until,表达式不达到上限 1 2 3 4 5 6 7 8 9
跳出循环语句
scala> import scala.util.control.Breaks._ import scala.util.control.Breaks._ scala> :paste // Entering paste mode (ctrl-D to finish) breakable { var n = 10 for(c <- "Hello World") { if(n == 5) break; print(c) n -= 1 } } // Exiting paste mode, now interpreting. Hello