scala - 在 Scala 中分配给 None 或 null 或 _ 的类(class)成员哪个更好，为什么？

Question

我有一个 Scala 域类(用于持久化数据库)
喜欢:

class Foo() {

var bar: Long = _ // or None or null ???
var jaz: String = _ // or None or null or empty string "" ???
}

如果字段 bar 和 jaz 是必填字段，而不是对答案的影响
是可选的？

Answer 1

来自 Scala 编程:

An initializer “= _” of a field assigns a zero value to that field. The zero value depends on the field’s type. It is 0 for numeric types, false for booleans, and null for reference types. This is the same as if the same variable was defined in Java without an initializer. Note that you cannot simply leave off the “= _” initializer in Scala ... [as it] would declare an abstract variable, not an uninitialized one

所以你上面的代码是一样的

class Foo() {

var bar: Long = 0
var jaz: String = null
}

Kim 的回答听起来是正确的 - 如果某个字段是可选的，请将其设为 Option，否则，请让构造函数对其进行设置。