Kotlin – Compare Objects with Comparable Example

https://grokonez.com/kotlin/kotlin-compare-objects-comparable-example

Kotlin – Compare Objects with Comparable Example

This tutorial shows you way to compare Objects with Comparable by an example.

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• Kotlin – Sort List of Objects with Comparable
• Kotlin – Sort List of Objects with Kotlin Comparator Example
• Kotlin Comparator Binary Search for Object List

I. Technology

• Java 1.8
• Kotlin 1.1.2

  II. Overview

  1. Goal

  First, we compare two objects Date(year:Int,month:Int,day:Int). Second, we continue to work on two Product(name:String,date:Date) objects.

  2. Steps to do

• Implement Comparable interface for the class of objects you want to compare.
• Override compareTo(other: T) method and:
• return zero if this object is equal other
• a negative number if it's less than other
• a positive number if it's greater than other

  III. Practice

  1. Create Classes

  
  package com.javasampleapproach.objcomparision

import kotlin.Comparable

data class Date(val year: Int, val month: Int, val day: Int) : Comparable {

override fun compareTo(other: Date) = when {
    year != other.year -> year - other.year
    month != other.month -> month - other.month
    else -> day - other.day
}

}

Product class includes Date field (implemented Comparable interface), so you can compare two Date objects inside using operator <,>,==.

More at:

https://grokonez.com/kotlin/kotlin-compare-objects-comparable-example

Kotlin – Compare Objects with Comparable Example