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♦ Find the first non repeated character in a given string input

Pseudocode 1) Precodnition check for null or empty input. 2) Loop throught the input string, and store each “character” as a key in a map with the value being the “character count”. For example, an input string of “stress” would…...

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Posted in Can you write code?, Coding, How to use Data Structures?, member-paid

01: ♦ 17 FAQ Java Collection Framework (i.e. JCF) interview Q&As on differences between X & Y

Java Collection interview questions and answers and Java String class interview Q&As are must know as you can’t write any decent Java application without these 2 APIs. This post focuses on Java Collection interview Q&As on differences between X and…...

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Posted in Collection and Data structures, Differences Between X & Y, FAQs Core Java, member-paid Tagged with:

02: ♦ 9 Java Collection interview Q&As on choosing the right data structure

Java Collection interview Q&As on choosing the right data structure as it is vital to choose the right data structure to get the job done with proper space vs performance trade-offs. Q1. What are the common data structures, and where…...

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Posted in Collection and Data structures, member-paid Tagged with: ,

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…...

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Posted in Collection and Data structures, FP, Java 8, Java 8 Tutorial, member-paid Tagged with:

03: Understanding Big O notations through Java examples

Q. Have you seen job advertisements requiring Java candidates to work in real-time or high volume transaction processing systems? If you are applying for such jobs, you can be quizzed on Big O notation. Here are some basics to brush up on. Big-O gives…...

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Posted in Big O notation, Collection and Data structures, Low Latency, member-paid

04: 7 Java Collection Quizzes

Q1. When is an object needs to implement the Comparable interface? a) When adding it to a HashSet. b) When adding it to a TreeSet. c) When adding it to a LinkedHashSet. d) When adding it to any Java Collection…...

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Posted in Collection and Data structures, member-paid, Written Test Core Java

05: ♦ 4 Sorting objects in Java interview Q&As

Sorting objects in Java interview Q&As especially understanding Comparable & Comparator interfaces in Java for natural & custom sorting respectively. Q1. If I mention the interface names Comparable or Comparator, what does come to your mind? Why do we need…...

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Posted in Collection and Data structures, member-paid

06: ♥♦ HashMap & HashSet and how do they internally work? What is a hashing function?

HashMap & HashSet are not only one of the frequently used data structures, but also one of the popular interview topics. Q1. How does a HashMap store data? A1. As key/value pairs. You can store and retrieve values with the

Posted in Collection and Data structures, FAQs Free, Objects, Understanding Core Java Tagged with: ,

07: ♥ Java Iterable Vs Iterator differences and know how

Q1. What are the differences between Iterator<T> Vs Iterable<T>? A1. The “Iterable” was introduced to be able to use in the “foreach” loop. A class implementing the Iterable interface can be iterated over. For example, Hence, it can be used

Posted in Collection and Data structures, Differences Between X & Y Tagged with:

08: ♦ If Java did not have a stack or map, how would you ….

Q1 If Java did not have a Stack implementation, how would you go about implementing your own? A1 1) Determine the backing data structure (e.g. array, linked list, etc). 2) Determine the methods that need to be implemented like pop(…...

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Posted in Collection and Data structures, member-paid

09: ♦ When to use which Java data structure? and why?

List, Set, Map, and Queue(access the ends FIFO or LIFO) are the basic Java data structure interfaces for which there are different implementations to cater for different usage patterns. Java data structure interview questions are very popular, and pays to…...

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Posted in Collection and Data structures, member-paid, Which Data Structure & WHy

10: ♦ 8 Java Maps & Caching Data in Java Interview Q&As

Q1. What is the purpose of a Map interface in Java collection API? A1. A map is a set of associations between pairs of objects. One is known as a “key” and the other is known as a “value”. It…...

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Posted in Collection and Data structures, member-paid, Memory Management, Performance

Java 8: Different ways to sort a collection of objects in pre and post Java 8

The object we are going to sort is a Person. Option 1: Writing your own Comparator implementation. This can be done as an anonymous inner class instead of a separate class. The test class Option 2: The Option 1 is…...

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Posted in How to use Data Structures?, Java 8, member-paid

Part-3: Java Tree structure interview and coding questions

This is an extension to Java Tree structure interview and coding questions — Part 2, and adds functional programming and recursion. Step 1: The Tree interface with get( ) method that returns either a Triple tree or Leaf data. Step 2:…...

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Posted in Coding, How to use Data Structures?, member-paid, Tree structure

Sorting a Map by values instead of keys

This post is motivated by ““Sorting a list or array of numbers by frequency of occurrences in Java” Sorting a Map by Keys Sorting a map by its keys is straightforward Sorting a Map by its Values – Pre Java

Posted in How to use Data Structures?

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