Scala Lazy 惰性加载变量 吗

Scala Lazy 惰性加载

• 原写法;

def main(args: Array[String]): Unit = {
    val result: Int = sum(13, 47)

    println("1. 函数调用")
    println("2. result = "   result)
    println("4. result = "   result)
  }

  def sum(a: Int, b: Int): Int = {
    println("3. sum调用")
    a   b
  }

• 输出

 - sum调用
 - 函数调用
 - result = 60
 - result = 60

• Lazy 用法

  def main(args: Array[String]): Unit = {
    lazy val result: Int = sum(13, 47)

    println("1. 函数调用")
    println("2. result = "   result)
    println("4. result = "   result)
  }

  def sum(a: Int, b: Int): Int = {
    println("3. sum调用")
    a   b
  }

• 输出

1. 函数调用
3. sum调用
2. result = 60
4. result = 60

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