Learning Resources

Roadmap

A day-wise roadmap to learn Java in 30 days. Each day lists the concepts to cover, the outcome you should be able to demonstrate, and the hours to prepare — with every concept linked to its lesson.

Day-Wise Plan

Complete Java Programming Roadmap

A structured 30-day plan that takes you from Hello World to OOP, collections, threads, and a project you can demo. Every day lists the concepts to study, the outcome you should be able to demonstrate, and the hours to budget. Concept names link straight to the full lesson.

30Days

6Phases

103Total hours

3–4Hours / day

Ph. 1 — Foundation Ph. 2 — Arrays, Strings & Methods Ph. 3 — Packages, Wrappers & Files Ph. 4 — Object-Oriented Java Ph. 5 — Exceptions, Generics, Lambdas & Threads Ph. 6 — Collections, Interview & Project

Choose Your Pace

Track	Duration	How to follow it	Best for
Fast track	15 days	About 7 hours a day. Pair up two consecutive days from each phase.	Full-time learners and placement season
Standard track	30 days	About 3–4 hours a day, exactly as the table below is laid out.	College students learning alongside classes
Relaxed track	60 days	About 2 hours a day. Split each day of the table across two sittings.	Working professionals and evening learners

Phase 1 — Foundation

Day 1 – Day 6 · 17 hrs

Goal: Install a JDK and master Java basics: types, I/O, operators, and control flow.

Day	Concepts to cover	Outcome	Hours
Day 1	Introduction to Java JDK, JRE, JVM, bytecode Hello World with javac / java	You can explain how Java runs on the JVM, install a JDK, and compile/run a first program.	2 hrs
Day 2	Java Fundamentals Program structure, tokens, keywords main method, comments, compilation	You can read a Java file and name its parts, and you know why main is public static void.	3 hrs
Day 3	Data Types & I/O Primitives, variables, final Scanner, printf, nextLine pitfalls	You can choose types confidently and write programs that read/print numbers and lines correctly.	3 hrs
Day 4	Operators Arithmetic, logical, bitwise, ternary Precedence and integer-division traps	You can evaluate expressions by hand and avoid = vs == and 5/2 style mistakes.	3 hrs
Day 5	Conditional Control Statements if / else if / else, switch Nested decisions, common bugs	You can implement branching logic with if and switch, and you know when each is clearer.	3 hrs
Day 6	Loops for, while, do-while, enhanced-for break, continue, nested loops	You can write any loop pattern (including for-each) and debug infinite-loop mistakes.	3 hrs
Phase total			17 hrs

Phase 2 — Arrays, Strings & Methods

Day 7 – Day 11 · 16 hrs

Goal: Work with collections of data and break problems into reusable methods.

Day	Concepts to cover	Outcome	Hours
Day 7	Arrays 1D / 2D arrays, traversal Why prefer ArrayList later	You can declare, initialise, and traverse arrays, and explain why length is a field.	3 hrs
Day 8	Strings Immutability, pool, equals vs == StringBuilder for loops	You can process String programs and explain why literals share the pool and why + in a loop is costly.	3 hrs
Day 9	Methods Parameters, return, overloading static vs instance, varargs	You can design small methods with clear signatures and overload by parameter list.	3 hrs
Day 10	Recursion Base case, call stack Recursion vs iteration	You can write factorial/Fibonacci-style recursion safely and explain stack growth / StackOverflowError.	3 hrs
Day 11	Mini practice day Combine loops, arrays, strings, methods Cheatsheet skim	You can solve 4–5 small problems end-to-end without looking up basic syntax.	4 hrs
Phase total			16 hrs

Phase 3 — Packages, Wrappers & Files

Day 12 – Day 16 · 16 hrs

Goal: Organise code, box primitives, and persist data with file I/O.

Day	Concepts to cover	Outcome	Hours
Day 12	Packages import, access, directory layout javac -d / classpath basics	You can place classes in a package, import them, and explain package-private access.	3 hrs
Day 13	Wrapper Classes Autoboxing, Integer cache parseXxx vs valueOf	You can convert between primitives and wrappers and avoid == on boxed numbers.	3 hrs
Day 14	File Handling Reader / Writer, Scanner on files try-with-resources preview	You can read/write text files and close streams safely.	3 hrs
Day 15	Command-line args and file utilities String + wrapper parsing from files Methods as helpers	You can build a tiny program that parses args and processes a text file line by line.	3 hrs
Day 16	Phase review + small file utility Packages + wrappers + files together	You can load records from a file into arrays/lists of simple values and print a report.	4 hrs
Phase total			16 hrs

Phase 4 — Object-Oriented Java

Day 17 – Day 22 · 21 hrs

Goal: Model problems with classes: encapsulation, inheritance, interfaces, and polymorphism.

Day	Concepts to cover	Outcome	Hours
Day 17	Classes & Objects Encapsulation Access specifiers, fields, new	You can design a class with private data and a clear public interface.	4 hrs
Day 18	Constructors this Keyword Overloading and this(...) chaining	You can initialise objects correctly and explain constructor chaining with this and super.	3 hrs
Day 19	Static Members static blocks, class vs instance When (not) to use static state	You can use static counters/utilities and explain why static methods have no this.	3 hrs
Day 20	Inheritance super, constructor order Composition vs inheritance	You can build a small hierarchy and explain when composition is better.	4 hrs
Day 21	Abstraction Interfaces abstract class vs interface, default methods	You can write abstract bases and interfaces, and know when each is the right tool.	4 hrs
Day 22	Polymorphism Overload vs override, @Override Dynamic dispatch via superclass refs	You can demonstrate runtime polymorphism with a superclass or interface reference.	3 hrs
Phase total			21 hrs

Phase 5 — Exceptions, Generics, Lambdas & Threads

Day 23 – Day 26 · 15 hrs

Goal: Handle failures, write type-safe reusable code, and run work concurrently.

Day	Concepts to cover	Outcome	Hours
Day 23	Exception Handling checked vs unchecked, try-with-resources	You can throw/catch, declare throws, and close files with try-with-resources.	3 hrs
Day 24	Generics Type parameters, diamond, wildcards intro Why erasure forbids new T()	You can write a simple generic class/method and use ArrayList without raw types.	4 hrs
Day 25	Inner Classes & Lambdas Anonymous classes, functional interfaces Method references	You can replace a one-method anonymous class with a lambda and name Predicate/Function/Consumer.	4 hrs
Day 26	Multithreading start vs run, synchronized, volatile join, race conditions, deadlock idea	You can start a worker thread, protect a shared counter, and explain why run() is not start().	4 hrs
Phase total			15 hrs

Phase 6 — Collections, Interview & Project

Day 27 – Day 30 · 18 hrs

Goal: Master the core collections, revise for interviews, and ship a project.

Day	Concepts to cover	Outcome	Hours
Day 27	Collections Overview ArrayList LinkedList	You can choose ArrayList as the default List and explain when LinkedList helps.	4 hrs
Day 28	HashSet HashMap Stack Queue Iterator	You can implement word counts with HashMap, unique membership with HashSet, and iterate safely.	4 hrs
Day 29	Top 100 Interview Q&A Top 50 Interview MCQ Cheatsheet revision	You can answer OOP + Collections + JVM staples out loud and score well on the MCQ set.	5 hrs
Day 30	Projects Ship one OOP/Collections project with README	You have a finished, demonstrable Java project you can walk an interviewer through end-to-end.	5 hrs
Phase total			18 hrs

After Day 30

Finishing the table is the start, not the finish. Keep momentum with these next steps.

Next step	Why it matters
Build one more OOP/Collections project	Employers trust working code far more than a list of topics.
Practice DSA with ArrayList, HashMap, and HashSet	Those three plus iterators are the daily toolkit for coding rounds.
Revise Q&A and the cheatsheet weekly	Spaced repetition keeps equals/hashCode, collections, and threads ready under pressure.
Explore JDBC, Spring, or Android next	All of them assume solid OOP, collections, and exception habits from Phases 4–6.