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Top “n” using a Priority Queue

If you ever need to capture the smallest or largest “n” from a stream of data, the approach more often than not will be to use a simple data-structure called the Priority Queue.  Priority Queues do one thing very well – once a bunch of data is added, it can return the lowest value (or the highest value) in constant ...

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Kotlin – Convert List to Map Examples

1. Overview In this tutorial, We’ll learn how to convert the List to Map in Kotlin programming. Let us explore the different ways to do it. 1. Overview In this tutorial, We’ll learn how to convert the List to Map in Kotlin programming. Let us explore the different ways to do this conversion. Kotlin provides a set of methods for ...

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How To Convert String to Float in Kotlin?

1. Overview In this tutorial, We will learn how to convert the String value to Float in Kotlin. This conversion is done using toFloat() method of String class. But there are many cases where it gives parsing errors for wrong inputs. 2. Kotlin String to Float using toFloat() Method Converting string to float is done with toFloat() method of string ...

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Kotlin – Convert Map to List Examples

1. Overview In this tutorial, We will learn how to convert the Map to List in kotlin programming. Map implementations such as HashMap or TreeMap can be converted into an ArrayList or List object. Let us explore thedifferent ways to do this conversion. 2. Converting HashMap to List in Kotlin Using ArrayList Constructor This approach is the simple one and ...

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Groovy Script 101 – Commonly Used Syntax Reference Guide

Groovy has been around on the Java scene since 2003. With over a decade’s worth of history, development and experience, it is a Java syntax compatible object oriented programming language that compiles into JVM bytecode. In a way, Groovy can be viewed as a flavor of Java without being actual Java. This is because it works on the Java platform ...

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Kotlin: Multi variable null check

Although not-null, immutable variables with sensible defaults are often desired, it is not always the case. It is sometimes required to check if multiple variables are not null. This post describes several variants of how to do this when smart casts are not possible because the variables are mutable. Consider the following example: class Person() { var name: String? = ...

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Validation in Kotlin: Valiktor

Bean Validation is the Java standard for validation and can be used in Kotlin as well. However, there are also two popular alternative libraries for validation available in Kotlin: Konform and Valiktor. Both implement validation in a more kotlin-like way without annotations. In this post we will look at Valiktor. Getting started with Valiktor First we need to add the ...

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Getting started with Ktor

Ktor (pronounced kay-tor) is an open source Kotlin framework for building asynchronous web applications. This post shows how to create a small RESTful CRUD service with Ktor. Getting started In this example we use Maven as build tool. Besides standard Kotlin dependencies we need to add the Ktor dependencies to our pom.xml: 01 02 03 04 05 06 07 08 ...

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