One or three variable modifiers
1. val: define constants
2, var: define a variable
3, lazy val: define lazy evaluation constants
Note: It is not necessary to specify the variable type explicitly, because Scala will automatically perform type deduction.
Two examples
F:\scala\command>scala
Welcome to Scala2.12.1(JavaHotSpot(TM)64-BitServer VM,Java1.8.0_101).
Typein expressions for evaluation.Ortry:help.
scala> val x =10
x:Int=10
scala> val y:Int=20
y:Int=20
scala> x + x
res0:Int=20
scala> res0
res1:Int=20
scala> res0*res1
res2:Int=400
scala> val z=res0+res1+res2
z:Int=440
scala> z =100
<console>:12: error: reassignment to val
z =100
^
scala>var a =200
a:Int=200
scala> a =300
a:Int=300
scala> val d=20
d:Int=20
scala> val e =30
e:Int=30
scala> lazy val f=d*e
f:Int=<lazy>
scala> f*10
res3:Int=6000
scala> f
res4:Int=600