get the day of the year as an integer in Kotlin Android Studio-CodePudding

I am trying to get the current day of the year as an integer to access within my program. I looked at the Kotlin Docs and found a function called getDay(). but when I type it into my program it gives me an error and says the function is not determined. I am using Android Studio with Kotlin and the minimum API is 21.

IDE code Error

CodePudding user response：

Date().getDay() or rather Date().day in Kotlin returns the day of the week so not what you want.

Calendar.getInstance().get(Calendar.DAY_OF_YEAR) is the correct function to use in Android.

Calendar, Date etc. have been replaced by new java.util.time classes with Java 8 so you should use LocalDate.now().dayOfYear but as @nuhkoca indicates in order to do that you need to enable Java 8 API desugaring support which is basically adding this to your build file (Kotlin DSL not Groovy):

compileOptions {
   isCoreLibraryDesugaringEnabled = true
   sourceCompatibility = JavaVersion.VERSION_1_8
   targetCompatibility = JavaVersion.VERSION_1_8
}

kotlinOptions {
   jvmTarget = "1.8"
}

CodePudding user response：

This getDay() method is part of the Date class. Check this: https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.js/-date/get-day.html

You must do something like:

val currentDay = Date().getDay()

CodePudding user response：

try this code :

import java.time.LocalDate
import java.util.*




fun main() {

    val cal = Calendar.getInstance()
    val day = cal[Calendar.DATE]
    val doy = cal[Calendar.DAY_OF_YEAR]

    println("Current Date: "   cal.time)
    println("Day         : $day")

    println("Day of Year : $doy")
}

CodePudding user response：

If you perform desugaring in order to be able to use Java 8 Time API back to API 21, you can then use this method to get the day of year

import java.time.LocalDate

val dayOfYear = LocalDate.now().dayOfYear
System.out.println(dayOfYear);

Answer: 289