scala對象的創建時間

Question

在斯卡拉，它說的對象是單身。所以我想知道什麼是對象的創建時間。

這就是我創建爲空兩個階文件：

object Singleton { 
def Singleton() = { 
    val time = System.currentTimeMillis() 
    println("creation time: " + time) 
} 
def getTime() = { 
    val time = System.currentTimeMillis() 
    println("current time: " + time) 
} 
} 

object Test { 
def main(args: Array[String]) = { 
    Singleton.getTime() 
    Thread sleep 10000 
    Singleton.getTime() 
} 
} 

輸出是：

 
current time: 1415180237062 
current time: 1415180247299 

So when is the Singleton object created??

Answer 1

Thank you rightføld, make some change and verified object just behaved as singleton, and created when first called

object Singleton { 
    def getTime() = { 
    val time = System.currentTimeMillis() 
    println("current time: " + time) 
    } 
    private def init() { 
    val time = System.currentTimeMillis() 
    println("creation time: " + time) 
    } 
    init() 
} 

object Test { 
    def main(args: Array[String]) = { 
    val time = System.currentTimeMillis() 
    println("before call: " + time) 
    Singleton.getTime() 
    Thread sleep 10000 
    Singleton.getTime() 
    } 
} 

output is:

before call: 1415183199534 
creation time: 1415183199732 
current time: 1415183199732 
current time: 1415183209735 

Answer 2

It is much easier to try it in Scala REPL:

scala> object Singleton { 
    | println("creation time: " + System.nanoTime()) 
    | def getTime = println("current time: " + System.nanoTime()) 
    | } 
defined module Singleton 

scala> def test = { 
    | println("before call: " + System.nanoTime()) 
    | Singleton.getTime 
    | Singleton.getTime 
    | } 
test: Unit 

scala> test 
before call: 1194990019328128 
creation time: 1194990019677693 
current time: 1194990019889606 
current time: 1194990020062275 

Answer 3

A scala object表現得像lazy val;它會在第一次被引用時被實例化。