Kotlin

Filter a Kotlin Map to get non-null values only

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Riccardo Lippolis

When dealing with Maps in Kotlin, sometimes we’re only interested in entries for which the value is not null. Although the Kotlin Standard Library contains a filterValues function that seems to be appropriate, this function does not do any type conversions, resulting in a Map which won’t contain null values, but is still a Map with values of a nullable type according to the compiler. There is a feature request for the JetBrains team to add this functionality, but for now it has not been implemented (yet?).

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Converting Char to Int in Kotlin

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Riccardo Lippolis

The Kotlin standard library contains a lot of helper functions on top of the Java standard library for our convenience. Some of those functions help us in converting between different data types. For example, the String.toInt() function converts a number formatted as String to its Int representation. But how do we accomplish the same with a Char? Spoiler alert: NOT by using Char.toInt()!

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Kotlin method reference to companion object function

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Riccardo Lippolis

Functions defined in Kotlin companion objects are often seen as the 'equivalent' of static methods in Java. Although there are some similarities, there are also some caveats you should be aware of. For example, how to use method references (or, to be pedantic: function references) to refer to functions defined in a companion object.

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Publish your backend API typings as an NPM package

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Christophe Hesters
In this post I suggest a way to publish your backend API typings as an NPM package. Frontend projects using can then depend on these typings to gain compile time type safety and code completion when using Typescript.

It’s quite common in a microservice style architecture to provide a type-safe client library that other services can use to communicate with your service. This can be package with a Retrofit client published to nexus by the maintainer of the service. Some projects might also generate that code from a OpenAPI spec or a gRPC proto file.

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