If you need information about anything? Google it! While I was trying to get the rating and review data through Google Review APIs based on the documentation and tutorials that are available online, I initially thought it would be an easy task, but it actually took me much longer than…

A Cheatsheet of HTTP Related Questions What is HTTP? HTTP stands for Hyper Text Transfer Protocol, used for transferring data over a network HTTP is the foundation of data communication between web clients (often browsers) and servers (often computers in the cloud) for the World Wide Web. Communication between client computers and web…

Java Memory Management — Java has automatic memory management that automatically performs garbage collection, which auto-release objects that are no longer in use to free up memory. Java Memory Structure Stack: primitive types (int, char, …) and holds a reference to heap objects. Heap: actual objects, objects store their value inside the heap. Stack vs Heap Stack…

Batching Processing (Offline System) Takes a large amount of input data and uses a background job to process them in a batch, and then sends it out maybe the next day Fault tolerance—failed tasks will be recalled and re-executed Idempotent operations—multiple executions of a job only perform once. Common examples…

Memory v.s. Disk Memory: fast access, small size, temporary storage Disk: slow access, large size, permanent storage Performing an operation inside memory is very fast but very expensive due to its limited memory. …

Thread is the smallest unit of execution scheduled by OS. A task is a work that is performed by a thread. A process is a set of threads that execute in the same shared environment. Executing multiple threads or processes at a time is called concurrency. Multi-thread programming is doing…

Any test is composed of 3 parts: Prerequisites that are needed The expectation of what the result should be Trigger to make the call that will be tested A rough example using RSpec — A testing library for Ruby subject { described_class.process(data: data) } let(:id) { 123456 } describe '#process'…

A Quick Overview of the OOP Concept — What Is Object-Oriented Programming? Class is an abstract blueprint (the source of the plan) used to instantiate more specific, concrete objects based on that blueprint. Use objects to represent things you are programming about, variables as properties, and functions as methods. Creates an object, so the object is the implementation of the class that…

I will cover the data structures including Arrays, Lists, Sets, Queues, and Maps here. Depending on whether the order of items matters, how items are sorted, and whether the list can contain duplicates, we can choose the suitable collection type that fits our needs. Data Structure is a collection of…