在 kotlin 中為自定義 class 實現不等式符號

Question

我有這個 class：

    

class Dog<T: Comparable<T>>(private val name: T, private val weight: T): Comparable<Dog<T>> {
 override fun compareTo(other: Dog<T>): Int {
  TODO("Not yet implemented")
 }
 
 override fun equals(other: Any?): Boolean {
  return (other is Dog<*>) && (other.weight == weight)
 }
}

我想根據weight比較任意兩只狗，而不是這樣的名字：

    fun main() {
     val dog1 = Dog("Dog1", 10)
     val dog2 = Dog("Dog2", 11)
    
     println(dog1 > dog2)
     println(dog1 <= dog2)

}

我不知所措，無法實現compareTo function。如果您能提供幫助，我將不勝感激。

Answer 1

如果weight需要通用，你可以試試這個Dog class：

class Dog<T : Comparable<T>>(private val name: String, private val weight: T): Comparable<Dog<T>> {
    override fun compareTo(other: Dog<T>): Int {
        return weight.compareTo(other.weight)
    }

    override fun equals(other: Any?): Boolean {
        if (other == null || other !is Dog<*>) return false
        return name == other.name && weight == other.weight
    }
}

只要確保您的weight已正確實施compareTo() function 即可。