Advertisements I have a list of items like val myList = listOf(1, 2, 3, 4, 5, 6, 7, 8) and need to take first three elements, whcih I do like this: myList.take(3).forEach { } and wnat to get the rest of elements by doing something like this: myList.restElements.forEach { } where the extension/function restElements lists… Read More How to get list managed correctly in Kotlin?

Advertisements I need to know What`s Qualifier and Retention annotations in Kotlin and when to use it in android development and why I see some developers create an Enum class which holds dispatchers like default and IO as i need to know when should i create this class ? >Solution : Qualifier and Retention Annotations… Read More What`s Qualifier and Retention annotations in Kotlin?

Advertisements fun main() { val regex = Regex("^[a-zA-Z\\s!@#\$%^&*()-_=+\\\\|\\[{\\]};:’\",<.>/?]*\$") val names = listOf("John Doe", ".Smith", "Alice.", "Doe#Smith", "Doe#Smith99", "65464546499", "MM66M") for (name in names) { if (!name.matches(Regex(".*\\d.*")) || regex.matches(name)) { println("$name is valid") } else { println("$name is invalid") } } } here we expect result John Doe is valid .Smith is valid Alice. is valid… Read More how validate allow characters & special character but not allow number with character or number in kotlin

Advertisements Here is a Piece of code in kotlin: val paymentConnection = payment.connect { connectionSucceed { … } connectionFailed { throwable -> … } disconnected { … } } how can i convert it to Java? the prototype in java is shown like this: @NotNull public final poolakey.Connection connect(@NotNull kotlin.jvm.functions.Function1<? super poolakey.callback.ConnectionCallback,kotlin.Unit> callback) >Solution :… Read More how do i convert this kotlin code to java

Advertisements I’m currently writing a script which checks username & password validity. The username should have between 3 and 20 characters and no special characters, except for ".", "_" and "@". Currently, this is my function: fun isValidUsername(username: String): Boolean { var usrnmlength = true var usrnmspecial = true if ((username.length < 3) or (username.length… Read More Checking if a string has no special characters except for ".", "_" and "@"

Advertisements In Kotlin we can use the Elvis operator ?: like this: val string: String = null ?: "something else" But what if "something else" is the result of a computation, like val string: String = null ?: { // do some comutations here "something else" } This won’t compile as the right hand side… Read More Elvis operator for computed values

Advertisements Hello so I have created a simple rock paper scissor game using Kotlin. But the computer seems to win everytime even though I had won technically. Please have a look at my code and help me. Thanks `package com.blinky.kotlinbasics fun main() { val computerChoice = "" var playerChoice = "" println("Rock, Paper or Scissor?… Read More Computer Wins Everytime in Rock Paper Scissor Game

Advertisements Hi I am having a kotlin function fun extension(name: String, init: LambdaReceiver.() -> Unit) { val lambdaReceiver = LambdaReceiver(name) lambdaReceiver.init() } where the second parameter accepts a lambda with receiver init: LambdaReceiver.() -> Unit, and the structure of LambdaReceiver looks like class LambdaReceiver(private val name: String) { private var test: Int? = null fun… Read More Kotlin Lambda with receiver accepts random function

Advertisements Wonder what is wrong with specifying Kotlin function parameter name when calling a function. In some situation it won’t work and I don’t know how to fix it. For example, this code works fine without specifying the parameters’ names: assertEquals( FakeDataSource.photosList, repository.getMarsPhotos(), ) But the same code with parameters name give me a compiler… Read More Why Kotlin function parameter names break the method call?

Advertisements We can filter all items in a list that are also contained in another list by list.filter(otherList::contains) However, I want to filter all items in a list that are NOT contained in the other list. How can I negate the above? Ofc, I can pass a lambda, for example list.filter { !otherList.contains(it) } but… Read More Negation of function reference in Kotlin