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Java Exercises

Build your Java confidence through focused coding challenges. This practice track is designed for developers preparing for technical interviews or sharpening their Java problem-solving skills

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Overview

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Getting better at Java for coding interviews is all about developing speed, clarity, and problem-solving intuition. This track gives you a space to drill high-impact Java challenges that test your knowledge of core data structures, algorithmic thinking, and common interview patterns. You’ll practice challenges built around arrays, linked lists, trees, stacks, recursion, hash maps, and more. Along the way, you’ll reinforce your understanding of Java-specific features like object-oriented design, exception handling, generics, and memory management. Each exercise follows a structured format—starting with warmups and moving into progressively harder interview-style challenges. The problems are grouped by topic and pattern so that your practice builds muscle memory, not just answers. With solution walkthroughs, hint-based support, and a frictionless coding environment, you’ll build precision and fluency that carries into real interviews.

Getting better at Java for coding interviews is all about developing speed, clarity, and problem-solving intuition. This track g...Show More

WHAT YOU'LL LEARN

How to solve Java problems the way top tech interviews expect—using structure, reusability, and clean syntax.

Efficient use of Java collections, recursion, and object-oriented design in problem-solving.

Repetition-based practice across core structures: arrays, trees, stacks, queues, and hash maps.

Confidence in implementing solutions in a Java coding environment.

Strategies for debugging, optimizing, and writing production-quality code using Java best practices.

How to solve Java problems the way top tech interviews expect—using structure, reusability, and clean syntax.

Content

JavaScript Challenges with PAL

51 Lessons

Design In-Memory File System

Employee Free Time

Logger Rate Limiter

Lowest Common Ancestor of a Binary Tree III

Schedule Tasks on Minimum Machines

Task Scheduler

Binary Tree Maximum Path Sum

Build Binary Tree from Preorder and Inorder Traversal

Design File System

Lowest Common Ancestor of a Binary Tree III

Maximum Depth of Binary Tree

Search Suggestions System

Remove nth Node from End of List

Serialize and Deserialize Binary Tree

Connect All Siblings of a Binary Tree

Flatten Binary Tree to Linked List

Set Matrix Zeros

Linked List Cycle

Rearranging Fruits

Search Suggestions System

Binary Tree Zigzag Level Order Traversal

Compilation Order

Design Add and Search Words Data Structure

Diameter of Binary Tree

Interval List Intersections

Linked List Cycle III

Snapshot Array

Validate Binary Search Tree

Reverse Linked List II

Split a Circular Linked List

Time-Based Key-Value Store

Binary Tree Paths

Height of Binary Tree After Subtree Removal Queries

LFU Cache

Merge Intervals

Build Binary Tree from Preorder and Inorder Traversal

Insert Interval

Kth Largest Element in a Stream

Build a Matrix with Conditions

Merge K Sorted Lists

Reorder Routes to Make All Paths Lead to the City Zero

Diameter of Binary Tree

Swapping Nodes in a Linked List

Developed by MAANG Engineers

Every Educative lesson is designed by a team of ex-MAANG software engineers and PhD computer science educators, and developed in consultation with developers and data scientists working at Meta, Google, and more. Our mission is to get you hands-on with the necessary skills to stay ahead in a constantly changing industry. No video, no fluff. Just interactive, project-based learning with personalized feedback that adapts to your goals and experience.

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Hands-on Learning Powered by AI

See how Educative uses AI to make your learning more immersive than ever before.

Personalized Interview Prep

Skip the LeetCode grind with a custom roadmap that adapts to your goals. Hands-on practice for Coding Interviews, System Design, and more.

Mock Interviews

Test your skills in a simulated interview setting. Receive personalized feedback based on your performance. Available for Coding Interviews, System Design, and more.

AI Prompt

Build prompt engineering skills. Practice implementing AI-informed solutions.

Code Feedback

Evaluate and debug your code with the click of a button. Get real-time feedback on test cases, including time and space complexity of your solutions.

Explain with AI

Select any text within any Educative course, and get an instant explanation — without ever leaving your browser.

AI Code Mentor

AI Code Mentor helps you quickly identify errors in your code, learn from your mistakes, and nudge you in the right direction — just like a 1:1 tutor!

Free Resources

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Frequently Asked Questions

Why should I practice Java instead of just reading about it?

Reading teaches you the concepts, but practice is what makes them stick. By working on coding problems or projects, you sharpen your problem-solving skills, spot patterns, and build confidence to apply Java in real situations.

What makes Java worth practicing in the first place?

Java is one of the most widely used languages in the world. Its stability, security, and portability make it a favorite for building everything from web apps to large enterprise systems. Practising Java means you’re investing in skills that are valuable across industries.

What topics should I focus on when practising Java?

Start small with variables, loops, and conditional statements. Then move into arrays, strings, and methods. Once those feel comfortable, tackle object-oriented concepts such as inheritance and polymorphism, followed by exception handling, multithreading, and functional programming with streams and lambdas.

How does Java practice still help me grow even if i’ve already worked with it?

Even experienced developers benefit from practice. Advanced problems and projects push you to think differently, optimize solutions, and explore areas like design patterns, database connectivity, or performance tuning. Continuous practice keeps your skills sharp and adaptable.

What’s a balanced way to practise Java effectively?

Mix short, focused exercises with longer projects. Small problems build fluency and accuracy, while projects let you see how the pieces fit together. Practising both ensures you’re not just solving isolated puzzles but also gaining the ability to design and build full applications.

How do I make practice truly “Java-y”?

Set a “feature of the day” (try-with-resources, streams, records, CompletableFuture) and force yourself to use it once meaningfully.

How can I turn mistakes while Java practice into practice fuel?

Keep a “bug diary”: copy the failing input, the fix, and the missing test. Re-drill the same pattern in a new problem within 48 hours.