object ReassignTest extends App {
class X(var i : Int)
def x = new X(10)
x.i = 20 // this line compiles
println(x.i) // this prints out 10 instead of 20, why?
}
那么我如何为参数 i
最佳答案
您将 x
定义为一个方法,它会在您每次“调用”它时返回一个新的 X
。
def x = new X(10) //define a function 'x' which returns a new 'X'
x.i = 20 //create a new X and set i to 20
println(x.i) //create a new X and print the value of i (10)
将 x
定义为一个值,行为将如您所愿
val x = new X(10) //define a value 'x' which is equal to a new 'X'
x.i = 20 //set 'i' to be to 20 on the value 'x' defined above
println(x.i) //print the current value of the variable i defined on the value 'x'
关于scala - 在 Scala 的构造函数上重新分配一个 var 参数,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/9980759/