1.x to 2.x migration: Observable vs. Observable: RxJava FAQ

The title is not a mistake. rx.Observable from RxJava 1.x is a completely different beast than io.reactivex.Observable from 2.x. Blindly upgrading rxdependency and renaming all…

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flatMap() and the order of events – RxJava FAQ

As we already discovered, flatMap() does not preserve the order of original stream. Let’s illustrate this using the GeoNames API example from previous article: public…

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flatMap() vs. concatMap() vs. concatMapEager() – RxJava FAQ

There are three, seamlessly similar operators in RxJava 2.x: flatMap(), concatMap() and concatMapEager(). All of them accept the same argument – a function from…

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Eager subscription – RxJava FAQ

While teaching and mentoring RxJava, as well as after authoring a book, I noticed some areas are especially problematic. I decided…

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Beware of slow transaction callbacks in Spring

TL;DR If your application is failing to obtain new database connection, restarting ActiveMQ broker may help. Interested? The problem with…

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Small scale stream processing kata. Part 2: RxJava 1.x/2.x

In part 1: thread pools we designed and implemented relatively simple system for processing events in real time. Make sure…

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Small scale stream processing kata. Part 1: thread pools

Once again I prepared a programming contest on GeeCON 2016 for my company. This time the assignment required designing and…

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Guide to time and date in Java

Properly handling dates, time, time zones, daylight saving time, leap years and such has been my pet peeve for a…

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Functor and monad examples in plain Java

This article was initially an appendix in our Reactive Programming with RxJava book. However introduction to monads, albeit very much…

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