Stream Storm2 min read
Why Collectors.toMap throws "Duplicate key", and how to fix it
toMap refuses to guess which value you want when a key repeats. Give it a merge function and the crash goes away.
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- Stream Storm2 min read
Java Streams: distinct, limit, reduce and groupingBy
Remove repeats, stop early, fold a list into one value, and sort items into groups, with the output of every example.
- Stream Storm3 min read
Java Streams for beginners: filter, map, flatMap, sorted
What a stream is, the four steps you'll use every day, and the one surprise that trips everyone up.