云星数据---Scala实战系列(精品版)】：Scala入门教程013-Scala实战源码-Scala表达式与for循环

Scala表达式及循环

package  scala_learn.demo00_helloworld

/**
* Created by liguohua on 2017/2/12.
*/
object Statements_04 {
def tes1(): Unit = {
//scala的表达式都是有返回值的，最后一个表达式作为函数的返回值，因此函数中应避免return
//一、以下是if语句的写法
if (true) {
println("good")
}
if (3 > 5) {
println("yes")
} else {
println("no")
}

val score = 90
if (score > 80) {
println("gread 1")
} else if (score > 70) {
println("gread 2")
} else {
println("gread 3")
}
//二、以下是while的写法
var i = 0
while (i < 5) {
println(i)
//scala不支持i++或者++i或者--i或者i--之类的操作
i += 1
}

//三、以下是for的写法
println("****************************for[0,5]**********************************")
//[0,5]
for (i <- 0 to 5) {
println(i)
}
println("****************************for[0,5)**********************************")
//[0,5)
for (i <- 0 until 5) {
println(i)
}
println("****************************for中可以写多个if需要用';'分开**********************************")
for (i <- 0 until 5; if i % 2 == 0; if i < 6) {
println(i)
}

println("****************************大致的for循环嵌套**********************************")
for (i <- 0 to 5; j <- 0 to 4) {
println("i=" + i + ",j=" + j)
}
println("****************************正方形打印**********************************")
for (i <- 0 to 5) {
for (j <- 0 to 5) {
print("*")
}
println()
}

println("****************************for中的yield(yield用于产生循环语句的返回值)**********************************")

val no1 = for (i <- 1 to 10) yield i
println(no1) //Vector(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

val no2 = for (i <- 1 to 10 if i % 5 == 0) yield i
println(no2) //Vector(5, 10)

}

def test2(): Unit = {
println("****************************scala中的break和countiue**********************************")
var a = 0
val numList = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
import scala.util.control._
val loop = new Breaks
loop.breakable {
for (a <- numList) {
println("Value of a: " + a)
if (a == 4) {
loop.break
}
}
}
println("After the loop")
}

def test3(): Unit = {
println("****************************scala中的break和countiue(循环嵌套)**********************************")
var a = 0
var b = 0
val numList1 = List(1, 2, 3, 4, 5)
val numList2 = List(11, 12, 13)
import scala.util.control._
val outer = new Breaks
val inner = new Breaks
outer.breakable {
for (a <- numList1) {
println("Value of a: " + a)
inner.breakable {
for (b <- numList2) {
println("Value of b: " + b)
if (b == 12) {
inner.break
}
}
} // inner breakable } } // outer breakable.
}
}
}

def main(args: Array[String]) {
tes1()
test2()
test3()
}

}