Scala 槽点 - require

require

def this(name: String, age: Int) = {   this()   require(name != null && !name.isEmpty, "name")   require(age > 0, "illegal age")   Preconditions.checkArgument(name != null && !name.isEmpty, "name required")  // 使用 guava 工具类，这行编译不过... 改写为下两种调用方式可通过 // Preconditions.checkArgument(name != null && !name.isEmpty, "name required".asInstanceOf[Any])   // Preconditions.checkArgument(name != null && !name.isEmpty, "name required", null)   setAge(age)   setName(name) }

什么鬼

1. require
   • 函数签名: final def require(requirement: Boolean, message: => Any) ，注意第二个参数类型是一个函数
   • 以上栗子中调用了两次 require 函数，生成两个匿名对象...
2. ambiguous reference to overloaded definition
   • 编译错误信息：
     Error:(44, 21) ambiguous reference to overloaded definition, both method checkArgument in object Preconditions of type (x$1: Boolean, x$2: String, x$3: Object*)Unit and method checkArgument in object Preconditions of type (x$1: Boolean, x$2: Any)Unit match argument types (Boolean,String) Preconditions.checkArgument(name != null && !name.isEmpty, "name required")

来源：博客园

作者：邓晓锋

链接：https://www.cnblogs.com/xsj24/p/11649402.html