版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/u012292754/article/details/85127956
1 函数的定义
def 方法名(参数名：参数类型):返回值类型 = {
// 方法体
//方法体内的最后一行是返回值，不需要 return
}
- 当函数没有输入的参数，调用的时候可以不写括号
package com.scalatest.scala.function
object FunctionApp {
def main(args: Array[String]): Unit = {
// println(add(2,3))
println(three())
println(three)
}
def add(x: Int, y: Int): Int = {
x + y
}
def three() = 1+2
}
2 默认参数
def main(args: Array[String]): Unit = {
sayName()
sayName("Jenny")
}
def sayName(name:String = "Mike")={
println("hi :" + name)
}
3 命名参数
调用函数的时候可以不按照参数的顺序传参
package com.scalatest.scala.function
object FunctionApp {
def main(args: Array[String]): Unit = {
println(speed(100, 25))
println(speed(distance = 100, time = 25))
println(speed(time = 25, distance = 100))
}
def speed(distance: Float, time: Float): Float = {
distance / time
}
}
4 可变参数
object FunctionApp {
def main(args: Array[String]): Unit = {
println(sum(1,2,3,4,5))
}
def sum(nums: Int*): Int = {
var res = 0
for (num <- nums) {
res += num
}
res
}
}
5 循环表达式
5.1 to(左闭右闭)
5.2 until
5.3 for
package com.scalatest.scala.function
object FunctionApp {
def main(args: Array[String]): Unit = {
for (i <- 1 to 10) {
print(i+" ")
}
println()
for (i <- 1 to 10 if i%2==0){
print(i+" ")
}
}
}
package com.scalatest.scala.function
object FunctionApp {
def main(args: Array[String]): Unit = {
val courses = Array("Hadoop","Spark","Hbase")
for(ele <- courses){
println(ele)
}
courses.foreach(ele => println(ele))
}
}
5.4 while
package com.scalatest.scala.function
object FunctionApp {
def main(args: Array[String]): Unit = {
var (num, sum) = (100, 0)
while (num > 0) {
sum += num
num = num - 1
}
println(sum)
}
}