GuideTechnology
11 min read
How one Java class can build on another, how overriding changes behaviour at runtime, how overloading is chosen at compile time, and why inheritance is easy to misuse. With the constructor-order trap, field hiding and the exact differences interviewers ask about.
GuideTechnology
12 min read
Why object-oriented programming exists and how Java expresses it: classes as blueprints, objects as instances, constructors, access modifiers, static versus instance members, and encapsulation as a way to protect the rules of your data. Built around a bank account that cannot go wrong.
GuideTechnology
13 min read
How to make a Java program choose and repeat: if, switch (old statement and modern expression), the loop forms, and how to organise code into methods. Includes the pass-by-value rule that interviewers love and the scope rules that cause mysterious compile errors.
GuideTechnology
15 min read
How Java stores and combines data: primitive types versus references, what happens when a number overflows, why integer division surprises people, how casting and conversion work, when to use var, and how arrays hold a fixed number of values.
GuideTechnology
15 min read
What Java actually is, how a .java file becomes a running program, what the JDK, JRE and JVM each do, and how to compile and run your first program. Plus the full roadmap of this 41-article course, from zero to a tested Spring Boot API.
CourseTechnology
A free 41-article course that takes you from your first Java program to a tested, secured Spring Boot and PostgreSQL backend, with three projects, real verified output and interview preparation. Modern Java 21 and later, with older styles labelled.
GuideTechnology
19 min read
Design APIs that clients can rely on: resources and URLs, HTTP methods and which are safe to retry, status codes, validation, error formats, cursor pagination, filtering, idempotency keys, rate-limit responses, versioning, and when gRPC or GraphQL fit better than REST.
GuideTechnology
19 min read
How to prepare for campus placements and fresher hiring in India: aptitude rounds, online coding assessments with fast input and output, technical interviews, CS fundamentals, explaining trade-offs, debugging under pressure and discussing projects honestly.
GuideTechnology
18 min read
A realistic week-by-week plan for working through this course around college or a job: what to learn, implement, practise and revise each week, with timed sessions, mock interviews, a spaced-revision schedule, and lighter and more intensive alternatives.
GuideTechnology
24 min read
Build a small, complete Java project that uses many data structures together: a practice tracker with spaced-repetition reviews, undo, title autocomplete and a prerequisite-based study order. Requirements, design, milestones, test cases and extension ideas, with no paid services.
GuideTechnology
23 min read
A step-by-step routine for coding interviews: clarify, work examples, state a brute force, optimize, agree on a plan, code, test and analyze. Includes a full sample dialogue, advice on getting unstuck, and checklists you can use in mock interviews.
GuideTechnology
22 min read
What to do when prefix sums are not enough: Fenwick and segment trees for range queries with updates (optional depth), and disjoint set union with path compression and union by size for connectivity, cycles and Kruskal's algorithm (the part worth knowing).
GuideTechnology
19 min read
A trie stores words so that shared prefixes share nodes, making insert, exact search and prefix search take time proportional to the word length. Build one in Java, compare array and map nodes, and use it for autocomplete, wildcards and shortest-prefix replacement.
GuideTechnology
21 min read
Apply the six-step DP workflow to climbing stairs, house robber, grid paths and the longest common subsequence. For each: state, transition, base cases, evaluation order, complexity and why it is correct, with full tables and reconstruction.
GuideTechnology
20 min read
Dynamic programming is recursion that remembers. Learn overlapping subproblems and optimal substructure, memoization and tabulation on Fibonacci, a repeatable six-step formulation workflow, and the coin change problem that greedy cannot solve.
GuideTechnology
24 min read
When BFS is enough and when it is not, Dijkstra's algorithm with a priority queue and its non-negative-weight limit, a glance at Bellman-Ford, and topological sorting with Kahn's algorithm and DFS for dependency order, including how to detect impossible orders.
GuideTechnology
24 min read
Vertices and edges, adjacency lists versus matrices, breadth-first and depth-first search, connected components, grids as graphs, and basic cycle detection in undirected and directed graphs, with complexity in terms of V and E.
GuideTechnology
20 min read
Binary numbers, the bitwise operators and Java's signed-integer behaviour, then the reasoned uses: parity, powers of two, counting bits, XOR, masks and subsets, plus GCD, modular arithmetic, fast exponentiation and the sieve of Eratosthenes.
