什么是Kotlin中Java静态最终字段的等价物？-WhatistheequivalentofJavastaticfinalfieldsinKotlin?

95  

According Kotlin documentation this is equivalent:

根据Kotlin的文档，这是等效的：

class Hello {
    companion object {
        const val MAX_LEN = 20
    }
}

Usage:

用法：

fun main(srgs: Array) {
    println(Hello.MAX_LEN)
}

Also this is static final property (field with getter):

这也是静态最终属性（带有getter的字段）：

class Hello {
    companion object {
        @JvmStatic val MAX_LEN = 20
    }
}

And finally this is static final field:

最后这是静态的最终字段：

class Hello {
    companion object {
        @JvmField val MAX_LEN = 20
    }
}

11  

if you have an implementation in Hello, use companion object inside a class

如果你在Hello中有一个实现，请在类中使用companion对象

class Hello {
  companion object {
    val MAX_LEN = 1 + 1
  }

}

if Hello is a pure singleton object

如果Hello是纯单例对象

object Hello {
  val MAX_LEN = 1 + 1
}

if the properties are compile-time constants, add a const keyword

如果属性是编译时常量，请添加const关键字

object Hello {
  const val MAX_LEN = 20
}

if you want to use it in Java, add @JvmStatic annotation

如果要在Java中使用它，请添加@JvmStatic注释

object Hello {
  @JvmStatic val MAX_LEN = 20
}

4  

For me

为了我

object Hello {
   const val MAX_LEN = 20
}

was to much boilerplate. I simple put the static final fields above my class like this

很多样板。我简单地将静态final字段放在我的类之上

val MIN_LENGTH = 10

class MyService{
}