Kotlin 中的平等 [英] Equality in Kotlin

问题描述

我正在学习 Kotlin，具有 C++ 和 Java 背景.我期待以下打印 true，而不是 false.我知道 == 映射到 equals.equals 的默认实现是否不比较每个成员，即 firstName 和 lastName?如果是这样，它会不会将字符串值视为相等(因为 == 再次映射到 equal)?显然，我在 Kotlin 中还没有正确理解平等与身份的关系.

I'm learning Kotlin, with a C++ and Java background. I was expecting the following to print true, not false. I know that == maps to equals. Does the default implementation of equals not compare each member, i.e. firstName and lastName? If so, wouldn't it see the string values as equal (since == maps to equal again)? Apparently there's something related to equality versus identity that I haven't got right in Kotlin yet.

class MyPerson(val firstName: String, val lastName: String)

fun main(args: Array<String>) {
   println(MyPerson("Charlie", "Parker") == MyPerson("Charlie", "Parker"))
}

推荐答案

您描述的默认 equals 实现仅适用于数据类.不适用于从 Any 继承实现的常规类，只需使对象等于自身即可.

The default equals implementation you're describing exists only for data classes. Not for regular classes where the implementation is inherited from Any, and just make the object equal to itself.

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