通过“-”截取字符串，indexOf和substring的scala中用法

val a = "aa-bc-xx"

val i = a.indexOf("-")

val x = a.indexOf("-",i)

val one = a.substring(0,i)

print(one)    //aa

val two = a.substring(i+1,x)

print(two) //bc

val three = a.substring(x+1)

print(three)   //xx