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Kotlin

Extending Flows to customise transaction validation

Through the use of flow extension, nodes running the same CorDapp can include extra validation to ensure that a transaction meets their specific requirements. The validation inside contracts focuses on the rules that must be adhered to by all transacting parties. Because of this, they are more general and focus on ensuring that no one is putting together invalid transactions. ...

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Running a Kotlin class as a subprocess

Last week I wrote a post on running a Java class as a subprocess. That post was triggered by my need to run a class from within a test without prebuilding a Jar. The only difference between what I wrote in that post and what actually happened was the language. I used Kotlin to write that test. Not Java. Therefore, ...

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Preventing invalid spending of broadcasted states

Corda is super flexible and will allow you to put together the code needed to write many complex workflows. This flexibility does come with one disadvantage. You, the developer, need to spend some time and thought on designing your application. No more blank contracts. No more responder flows that sign anything they receive. You’ll be glad you put in the ...

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Kotlin vs Scala: which is right for you?

Kotlin or Scala? Scala or Kotlin? The two contenders for the crown of the JVM Kingdoms and the title of “Better Java” each bring something unique to the fight. But which should be the next ruler of your code? Java is old. Not that there’s anything wrong with being old. Sometimes it can be a good thing. Math is old ...

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Kotlin primitive and object arrays

I initially set out to write this post because I was playing around with some reflection code and thought I found something interesting. Alas, that was definitely not the case. Instead, it was just a basic feature of Kotlin that I haven’t needed to use or focus on yet. Although this post didn’t turn out the way I wanted it ...

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5 Kotlin Features That Every Android App Developer Must Know

Java is considered to be the heart of the Android operating system and so for every Android developer, there is hardly any alternative than knowing Java. Well, at last, a superb alternative to Java has appeared with a lot of value packed within. Kotlin is a new programming language comes as a better and more effective alternative to Java for ...

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Water Pouring Problem with Kotlin and Vavr

The first time I saw the Water Pouring Problem being programmatically solved was the excellentlectures on functional Programming by Martin Odersky on Coursera. The solution demonstrates the power oflazy evaluation in Streams with Scala. Solving Water Pouring Problem using Kotlin I wanted to explore how I can rewrite the solution described by Martin Odersky using Kotlin and I realized two ...

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Testing exceptions in Kotlin with assertFailsWith

I wanted to write this short post to highlight the assertFailsWith function available to Kotlin that makes testing exceptions a bit easier. Testing exceptions isn’t something fancy or new to JVM languages (from now on I will use Java for comparisons) but Kotlin comes with the nice extra benefit of providing this functionality as part of its standard library. Comparing ...

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Storing when block subject in a variable

Super short post, on a change introduced in Kotlin 1.3 (yes I know it has been out for a while now). We will take a quick look at capturing the subject of a when block into a scoped variable. This is a quality of life improvement that saves a line or so of code while making the role of the ...

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