Java is a versatile programming language, and you can use it to create a wide range of projects, from simple command-line utilities to complex web applications and mobile apps. The type of project you choose to work on depends on your interests, goals, and level of expertise. Here are some project ideas across different domains that you can consider:

1. To-Do List Application: Create a simple to-do list app with a graphical user interface (GUI) using Java Swing or JavaFX. Allow users to add, edit, and delete tasks.

2. Chat Application: Build a real-time chat application using Java sockets or a higher-level framework like Java NIO. Implement both server and client components.

3. Expense Tracker: Develop an application for tracking personal expenses. Users can enter expenses, categorize them, and view reports or charts of their spending.

4. Library Management System: Create a library management system that allows librarians to add, update, and search for books, manage user accounts, and track borrowing and returning of books.

5. Blog or Content Management System (CMS): Build a web-based CMS where users can create, edit, and publish blog posts or articles. Use Java frameworks like Spring Boot for backend development.

6. E-commerce Website: Create an online store with features like product listings, shopping carts, user authentication, and payment processing using Java and a web framework like Spring MVC.

7. Weather App: Develop a weather forecasting application that fetches data from a weather API and displays current weather conditions and forecasts for a given location.

8. Inventory Management System: Build an inventory management system for businesses to track product stock, sales, and order processing.

9. Game Development: Create a simple game using a Java game development library like LibGDX or JavaFX. Games like Tetris, Sudoku, or a platformer are good starting points.

10. RESTful API: Design and implement a RESTful API using Java and a framework like Spring Boot. You can develop APIs for various purposes, such as providing data to mobile apps or web frontends.

11. Personal Finance Tracker: Build an application that helps users manage their personal finances, including income, expenses, budgeting, and financial goals.

12. Student Information System: Develop a system to manage student records, grades, and course schedules for educational institutions.

13. Social Media Dashboard: Create a dashboard that aggregates and displays data from multiple social media platforms, such as Twitter, Facebook, and Instagram.

14. Employee Management System: Design an application for HR departments to manage employee information, payroll, attendance, and performance evaluations.

15. Mobile App: If you’re interested in mobile development, consider creating a mobile app for Android or iOS using Java and platform-specific SDKs (Android Studio for Android and Xcode for iOS).

16. Data Visualization: Develop a data visualization tool that allows users to upload and explore datasets, create charts, graphs, and dashboards.

17. Machine Learning: Work on a project involving machine learning and data analysis using libraries like TensorFlow or Weka. For example, create a sentiment analysis tool or a recommendation system.

18. Home Automation: Build a home automation system that allows users to control smart devices and monitor their home remotely.

19. Robotics: If you have access to robotics hardware, create a robot or automation project using Java and libraries like ROSJava for robotic control.

20. Open Source Contributions: Contribute to open source Java projects that align with your interests. This can be an excellent way to gain experience and collaborate with the open source community.