Core Programming (Java)
The language you will code every interview answer in, from variables to internals. C++ and Python versions are planned.
About Core Programming (Java)
Java is a statically typed, object-oriented language created at Sun Microsystems in 1995 and now maintained by Oracle and the OpenJDK community. You write source code once, the compiler turns it into bytecode, and the Java Virtual Machine (JVM) runs that bytecode on any operating system.
It powers Android apps, most large backend systems at banks and product companies, and tools like Kafka and Elasticsearch. Its strict types, garbage collector and huge standard library make it a safe first language for interviews.
Why it matters for placements
Most service and product companies let you code in Java, and interviewers often follow up with questions on how it works underneath: the JVM, memory, strings and threads.
What you'll learn
7 topics · 32 lessons, each with practice
- Write and run complete Java programs, reading input and printing output
- Use variables, operators, conditions, loops and methods with confidence
- Work with arrays and strings, and know why String is immutable
- Handle errors with exceptions instead of crashing
- Explain JVM internals: stack vs heap, garbage collection, the String pool
- Start threads safely and explain synchronization in an interview
Foundation Foundation
Take Foundation testRequired. Enough to clear online assessments and service-company interviews.
Basics
Not startedEvery coding round starts with reading input, storing values and printing an answer. Small mistakes here, like integer division or a lost newline after nextInt(), cost marks even when your logic is right. Get these habits solid before anything else.
Control Flow
Not startedReal programs do not run top to bottom once. They make choices and repeat work, and control flow is how you tell Java to do that. Almost every coding question uses at least one condition and one loop.
Functions
Not startedFunctions let you name a piece of logic, reuse it and test it on its own. Interview code is easier to read and debug when it is split into small methods, and recursion, which most DSA topics depend on, is built on them.
Arrays & Strings
Not startedMost input in coding rounds arrives as a list of numbers or a piece of text. Arrays and strings are the first data structures you will use in almost every problem, and Java strings have a few behaviours that often appear in output questions.
Interview Ready Interview Ready
Take Interview Ready testRecommended. Enough for technical rounds at good product companies.
Exception Handling
Not startedReal programs meet bad input, missing files and failed connections. Exception handling lets you deal with these without crashing, and the checked versus unchecked rules are a favourite interview topic for Java roles.
Java Internals
Not startedKnowing how the JVM stores and frees memory explains many confusing outputs and errors. These are standard theory questions in Java interviews, and they help you reason about bugs like StackOverflowError or unexpected == results.
Advanced Advanced
Take Advanced testOptional. For top product companies. Never counted against your readiness.
Multithreading
Not startedModern apps do several things at once, like serving many users or downloading while the screen stays responsive. Threads make that possible but bring bugs such as lost updates, so product-company interviews often test the basics here.