To crack a product-based company as a software engineer, it's important to focus on both technical skills and interview preparation. Here's a roadmap for the next four months to help you prepare:

Month 1: Strengthen Core Technical Skills

1. Review Java Fundamentals: Brush up on your Java skills, including object-oriented programming, data structures, algorithms, and exception handling.

2. Master JavaScript and React: Dive deeper into JavaScript and React development by building complex applications, studying advanced concepts, and exploring best practices.

3. Learn Backend Technologies: Familiarize yourself with popular backend technologies like Node.js, Express.js, and databases (e.g., MongoDB, MySQL) to develop full-stack applications.

4. Practice Data Structures and Algorithms: Solve coding challenges on platforms like LeetCode, HackerRank, or CodeSignal to improve your problem-solving abilities and enhance algorithmic thinking.

Month 2: Build Real-world Projects

1. Identify Project Ideas: Think of practical projects that showcase your skills and demonstrate your ability to build scalable web applications.

2. Implement Full-stack Projects: Develop end-to-end projects using your preferred tech stack, combining frontend (React) and backend (Node.js) technologies.

3. Deploy Projects: Host your projects on platforms like Heroku, Netlify, or AWS to gain experience in deployment and showcase your work to potential employers.

4. Collaborate on Open Source Projects: Contribute to open-source projects relevant to your skill set. This demonstrates your ability to work in a team and your commitment to learning from others.

Month 3: Interview Preparation

1. Study Data Structures and Algorithms: Review essential data structures (arrays, linked lists, stacks, queues, trees, graphs, etc.) and algorithmic concepts (sorting, searching, recursion, dynamic programming, etc.).

2. Solve Interview Questions: Practice solving coding interview questions from reputable resources such as "Cracking the Coding Interview" by Gayle Laakmann McDowell or LeetCode's interview-specific problems.

3. Mock Interviews: Participate in mock interviews with friends, colleagues, or through online platforms like Pramp or Interviewing.io to improve your interview skills and gain confidence.

Month 4: Enhance Soft Skills and Resume

1. Improve Communication Skills: Work on your verbal and written communication skills, as effective communication is crucial during interviews and when working in teams.

2. Develop a Strong Resume: Update your resume to highlight relevant projects, internships, certifications, and any other achievements that showcase your technical expertise.

3. Networking and Job Search: Attend tech meetups, conferences, and online events to expand your professional network. Leverage platforms like LinkedIn and job boards to find suitable job openings.

Throughout the entire preparation period, it's important to stay consistent, practice regularly, and keep up with the latest industry trends. Remember to revise important concepts, ask for feedback on your projects and code, and stay confident during the interview process. Good luck with your preparation and job search!