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01: ♦ 19 Java 8 Functional Programming (i.e. FP) interview Q&As

Good handle on Java OOP concepts and FP concepts are very important NOT only from writing quality code perspective, but also from job interviews perspective to be able to do well in written tests & technical interviews. Q1. Can you explain your understanding of Functional Programming (FP)? A1. In a…...

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Posted in FAQs OOP & FP, FP, Java 8, member-paid

02: ♦ Java 8 Streams, lambdas, intermediate vs terminal ops, and lazy loading with simple examples

A stream is an infinite sequence of consumable elements (i.e a data structure) for the consumption of an operation or iteration. Any Collection<T> can be exposed as a stream. It looks complex, but once you get it, it is very simple. The operations you perform on a stream can either…...

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Posted in Collection and Data structures, FP, Java 8, Java 8 Tutorial, member-paid
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03: ♦ Functional interfaces and Lambda expressions Q&A

The functional interfaces and Lambda expressions are going to make your code concise when coding with Java 8. These are the most awaited features among Java developers. If you understand the following examples, you will know what a lambda expression is & why functional interfaces were introduced in Java 8 to…...

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Posted in FP, Java 8, member-paid

04: ♦♥ 5 FAQs on transforming your thinking from OOP to FP

One needs to get used to the transformation from imperative programming to functional programming. You like it or not, you will be using functional programming in Java, and interviewers are going to quiz you on functional programming. Fortunately, Java is not a fully functional programming language, and hence one does

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Posted in FAQs OOP & FP, FP, Java 8
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04: Convert Lists to Maps and Maps to Lists with Java 8 power

Why convert from a list to a map? Maps allow you to store and access data by a “KEY”. Lists only allow you to access data by either index or by looping through the whole list to find a value that you are interested in. Also, a map can be…...

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Posted in Converting from A to B, Java 8, member-paid

05: ♥ 7 Java FP (lambda expressions) real life examples in wrangling normal & big data

This post extends Transforming your thinking from OOP to FP. In Big-data, functional programming is prevalent when working with data sets. For example, writing a Spark job to work with RDDs (Resilient Distributed Data sets). In Imperative (E.g. OOP, procedural programming, etc) programming you can say where you are assigning

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Posted in FP, Java 8

05: ♦ Finding the 2nd highest number in an array

Requirements gathering Does the array allow duplicates? If duplicates are allowed, then do you need to report duplicates? For example, in {2,4, 6, 3, 6, 5}, is 6 or 5 the second highest? Analysis If duplicates are not allowed, sort the array (Arrays.sort(…)) and get the second last element, which…...

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Posted in Can you write code?, Coding, Java 8, member-paid

06: ♥ Understanding TimeZones with Java 8 examples

What is UTC? which stands for Coordinated Universal Time. The diagram below shows the standard time offsets of different countries. Some places observe daylight saving time (DST) during their respective summer periods. For example, Los Angeles (i.e LA) UTC – 8.0 hours (without DST) & UTC – 7.0 hours (with

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Posted in Data types, Java 8

06: ♥ Java 8 way of File reading and functionally processing the data

Output: #1 double colon notation :: The new double colon (::) operator that Java 8 has to convert a normal method into lambda expression. So, Instead of: You can do: #2 Why is stream::iterator used? “lines::iterator” where iterator() is an instance method on “BaseStream<T,Stream<T>>” from which java.util.Stream<T> extends. The “iterator()”

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Posted in IO, Java 8
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07: ♦ Java 8 API examples using lambda expressions and functional programming

Java 8 API examples using lambda expressions and functional programming. Example 1: The java.lang.Runnable interface has been made a functional interface. Output: main thread: main worker thread: Thread-0 worker thread: Thread-1 Example 2: The java.util.function package has a number of functional interfaces. Output: consumed: 5 consumed: 25 consumed: 6 consumed:…...

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08: ♦ Write code to add, subtract, multiply, and divide given numbers?

A trivial coding example (i.e. a Calculator) tackled using the following programming paradigms in Java not only to perform well in coding interviews, but also to learn these programming paradigms. Approach 1: Procedural Programming Approaches 2 – 4: Object Oriented Programming Approach 5: Functional Programming (Java 8) Approach 1: Procedural

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Posted in Can you write code?, Coding, Java 8, OOP

10: ♦ ExecutorService Vs Fork/Join & Future Vs CompletableFuture Interview Q&As

Q1. What is the difference between “ExecutorService” and “Fork/Join Framework“? A1. The Fork/Join framework uses a special kind of thread pool known as the ForkJoinPool, which is a specialized implementation of ExecutorService implementing the 1) work-stealing algorithm, in which the idle workers steal the work from those workers who are

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Posted in Java 8, Multithreading, Reactive Programming

Fibonacci number with caching and Java 8 FP

Complimenting Fibonacci number coding – iterative and recursive approach, we can improve performance by caching. If you run this Output and you can see “fibonacci(3)” is repeated 2 times, “fibonacci(2)” is repeated 3 times, and so on. If you pick a larger number like 21, there will be many repeats.…...

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Java 8 String streams and finding the first non repeated character with functional programming

Q1.Find the first non repeated character in a given string input using Java 8 or later? A1.Extends Find the first non repeated character in a given string input with Java 8 functional programming. Examples to understand string streams: Example 1 Output: Example 2 Output: Example 3 Output: Example 4 Output:…...

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Java 8 using the Predicate functional interface

The java.util.function package in Java 8 has a number of functional interfaces. Let’s look at the Predicate interface that is used for filtering objects from a collection. Here is the Java 8 example: Step 1: Create a Driver domain class using the builder design pattern. If not sure how to…...

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