CampusCrate is a student operating system for B.Tech students in India, combining opportunities, academic resources, communities, learning hubs, and career tools in one platform.

Who is CampusCrate built for?

CampusCrate is built for Indian engineering and B.Tech students who need a structured place to discover opportunities, access college resources, join societies, learn technical skills, and build their career profile.

What can students find on CampusCrate?

Students can find hackathons, internships, competitions, notes, test papers, cheatsheets, college communities, DSA and development learning tracks, roadmaps, profiles, and AI career tools.

☕Java

Write once, run anywhere — Android apps, banks, big enterprise. Strong typing, JVM speed, mature ecosystem.

📘Theory & Lessons 💻Code Examples 🔗HackerRank Java

4 Phases · 16Topics · Basic → Advanced

Phase 1

Java Basics

4 topics

☕

Introduction to Java

What Java is, JDK vs JRE vs JVM, installing OpenJDK, and your first Hello World.

📦

Variables & Primitive Types

int, long, double, boolean, char, String — primitives vs objects, autoboxing, and var (Java 10+).

💬

I/O — Scanner & System.out

Reading input with Scanner, BufferedReader, formatted printing with printf and String.format.

🔀

Control Flow & switch

if / else, while, for, enhanced for-each, classic switch, and modern switch expressions (Java 14+).

Phase 2

Methods, Strings & Arrays

4 topics

⚙️

Methods & Overloading

Defining methods, parameters, return types, overloading, varargs, and recursion.

🔤

Strings & StringBuilder

String immutability, common methods, StringBuilder for efficient mutation, text blocks (Java 15+).

📊

Arrays & Arrays Utility

Fixed-size arrays, 2D arrays, java.util.Arrays — sort, fill, equals, toString, copyOf.

🏗️

Classes, Objects & Encapsulation

Defining classes, fields, constructors, this, getters/setters, access modifiers, records (Java 14+).

Phase 3

OOP & Collections

4 topics

🧬

Inheritance, Interfaces & Polymorphism

extends vs implements, abstract classes, default methods, Comparable & Comparator.

🚨

Exceptions & try-with-resources

Checked vs unchecked exceptions, try/catch/finally, custom exceptions, AutoCloseable.

📚

Collections Framework

List, Set, Map — ArrayList, LinkedList, HashSet, HashMap, TreeMap; when to use each.

🧩

Generics

Generic classes & methods, wildcards (? extends, ? super), type erasure caveats.

Phase 4

Modern Java & Practice

4 topics

Lambdas & Functional Interfaces

() -> ..., method references, Function, Predicate, Consumer, Supplier from java.util.function.

🌊

Streams API

stream(), filter, map, reduce, collect — declarative pipelines over collections.

🚀

Optional, Records & Modern Java

Optional<T>, records, sealed classes, pattern matching, switch expressions, var.

🏆

Practice & Projects

Curated problems on LeetCode and HackerRank, plus build ideas — REST API, Android, Spring Boot.