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Tag Archives: Java 8

The JDK 8 SummaryStatistics Classes

Three of the new classes introduced in JDK 8 are DoubleSummaryStatistics, IntSummaryStatistics, and LongSummaryStatistics of the java.util package. These classes make quick and easy work of calculating total number of elements, minimum value of elements, maximum value of elements, average value of elements, and the sum of elements in a collection of doubles, integers, or longs. Each class’s class-level Javadoc ...

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How to FlatMap a JDBC ResultSet with Java 8?


You’re not into the functional mood yet? Then the title might not resonate with you – but the article will! Trust me. Essentially, we want this: +------+------+------+ | col1 | col2 | col3 | +------+------+------+ | A | B | C | row 1 | D | E | F | row 2 | G | H | I | ...

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Java 8 Lambdas in One Line

If you understand this line, or better still can write this code you can pretty much say that you have understood the essence of Java 8 Lambdas. Certainly in as much as they can be used with collections. I found this in a recent presentation by Peter Lawrey.  (Definitely worth watching the whole presentation when you have a spare hour.) Anyway ...

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How to Use Java 8 Streams to Swiftly Replace Elements in a List

Imagine you have a list of items: List<String> books = Arrays.asList( "The Holy Cow: The Bovine Testament", "True Hip Hop", "Truth and Existence", "The Big Book of Green Design" ); (Don’t judge me. Books from this random book generator) Now you’d like to create a new list where the third item only is replaced by some new value: List<String> books ...

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Yet another Java 8 Lamdbas and Streams example

I’ve been lagging behind with what Java 8 features exercising concerns, so in this post I will briefly present my initial experience with lambdas and streams. As usual, I will focus on a Podcast class:               package org.codingpedia.learning.java.core; import java.util.Comparator; public class Podcast { int id; String title; String producer; int subscriptionsNumber; /** number of ...

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Java 8 Lambda Expressions Tutorial

Greetings! :) After a few months away I decided to come back in style :). I noticed that one of my previous posts about the new Date/Time API got really popular, so this time I’m going to dedicate this post to another new feature of Java 8: Lambda Expressions. Functional Programming Lambda Expressions are the way by which the Java ...

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JDK 8 Streams and Grouping

I wrote about the powerful features of using JDK 8‘s Streams with Java collections in the post Stream-Powered Collections Functionality in JDK 8. I did not cover use of the groupingBy Collector reduction operation in that post and so address grouping in this post. The examples in this post will demonstrate how to combine Collection-backed Streams with groupingBy Collectors to ...

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Walking Recursive Data Structures Using Java 8 Streams

The Streams API is a real gem in Java 8, and I keep finding more or less unexpected uses for them. I recently wrote about using them as ForkJoinPool facade. Here’s another interesting example: Walking recursive data structures. Without much ado, have a look at the code:             class Tree { private int value; private ...

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