Blog Archives

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

Choosing the right data structure is vital to get the job done with proper space vs performance trade-offs. Q1. What are the common data structures, … Read more ›...

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. …...

03: Understanding Big O notations

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, … Read more ›...

04: 7 Java Collection Quizzes

Q1. When is an object needs to implement the Comparable interface? a) When adding it to a HashSet. … Read more ›...

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. … Read more ›...

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?

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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.

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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. … Read more ›...

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. …...

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. … Read more ›...

17 FAQ Java Collection interview Q&As

Java Collections 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...

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...

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 –

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800+ Java Interview Q&As