在 Kotlin 中克隆对象

Question

我有 3 个 class 如下：

Company.kt class:

data class Company(var comCode:String= "",var comName:String=""):Cloneable{
fun copy() : Company {
  //uses the fields name and property defined in the constructor
  return Company(comCode,comName)
}

override fun clone(){
    super.clone()
}
}

Emp.kt class:

 data class Emp(var name:String,var empCode:String,var nameArray:MutableList<Company>){

fun copy() : Emp {
  //uses the fields name and property defined in the constructor
  return Emp(name,empCode,nameArray)
}

//or if you need a copy with a changed field
fun copy(changeArray :MutableList<Company>) : Emp {
  return Emp(name,empCode ,changeArray)
}

}

DeepCopy.kt class:

fun main(args:Array<String>){

var company1 = Company("com1","company1")
var company2 = Company("com2","company2")
var company3 = Company("com3","company3")
var company4 = Company("com4","company4")
var company5 = Company("com5","company5")

var list:MutableList<Company> =mutableListOf();
    list.add(company1)
    list.add(company2)
    list.add(company3)
    list.add(company4)
    list.add(company5)
val emp = Emp("krishan","oms360",list)
println("old emp>>>>>>> "+emp.nameArray[1].comCode)
val listtemp = emp.nameArray
listtemp[1].comCode= "COM10";
//var cloneEmp = emp.copy(listtemp)//.apply { this.nameArray[1].comCode= "COM10"; }
//cloneEmp.nameArray[1].comCode= "COM10";
//cloneEmp.empCode = "oms400"
println("new emp>>>>>>> "+emp.nameArray[1].comCode)

}

当我像这样从新对象中的 emp 对象获取 nameArray 时

val listtemp = emp.nameArray
listtemp[1].comCode= "COM10";

并更改列表第一个位置的值，在打印 emp 对象之后，该对象打印 changes()。

结果：

old emp>>>>>>> com2
new emp>>>>>>> COM10

Answer 1

我假设代码中取消注释的部分是您尝试进行深层复制的地方，它最终也更改了 emp 对象，否则您的问题没有意义，因为代码明显更改 emp 对象。如果我假设正确，请尝试将 copy() 函数更改为：

data class Company(var comCode: String= "",var comName: String= "") {
    fun deepCopy(comCode: String = this.comCode, comName: String = this.comName) 
        = Company(comCode, comName)
}

--

data class Emp(var name: String,var empCode: String,var nameArray: MutableList<Company>){

    fun deepCopy(
        name: String = this.name, 
        empCode: String = this.empCode, 
        nameArray: MutableList<Company> = this.nameArray.map {it.deepCopy()}) = Emp(name, empCode, nameArray)
}

然后，如果你想制作一个副本，就这样做：

val newEmp = emp.deepCopy()
// val newEmp = emp.deepCopy(empCode = newEmpCode) // in case you want a different code for your newEmp. Similarly for other fields.

Answer 2

通用克隆函数：

fun <T : Any> clone (obj: T): T {
  if (!obj::class.isData) {
    println(obj)
    throw Error("clone is only supported for data classes")
  }

  val copy = obj::class.memberFunctions.first { it.name == "copy" }
  val instanceParam = copy.instanceParameter!!
  return copy.callBy(mapOf(
    instanceParam to obj
  )) as T
}

在 Kotlin 中克隆对象

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