Scala val 和 var 的区别

Scala官网：https://docs.scala-lang.org/tour/basics.html

val（Values）

　　Named results, such as x here, are called values. Referencing a value does not re-compute it.

　　x = 3 // This does not compile.

var（Variables）

　　Variables are like values, except you can re-assign them. You can define a variable with the var keyword.

　　var x = 1 + 1

　　x = 3 // This compiles because "x" is declared with the "var" keyword.

　　println(x * x) // 9