What Are Java Libraries?

Java libraries are collections of pre-written code that you can use in your own programs. Each library groups together useful classes, methods, and functions that solve common programming tasks.

Why Use Java Libraries?

• Save time by reusing reliable, well-tested code;
• Avoid "reinventing the wheel" for common features, such as reading files or working with dates;
• Simplify your code by using clear, ready-made solutions;
• Make your programs more robust and easier to maintain.

Java libraries cover a wide range of needs, from handling data and building user interfaces to connecting to databases and testing code. By using libraries, you can focus on the unique parts of your application while relying on proven solutions for everything else.

Standard Libraries, Third-Party Libraries, and Frameworks in Java

Understanding the distinction between standard libraries, third-party libraries, and frameworks in Java helps you select the right tools for your projects:

Standard Libraries

• Provided by the official Java Development Kit (JDK);
• Include packages such as java.util, java.io, and java.math;
• Offer foundational features like data structures, file handling, networking, and math operations;
• Are always available with every Java installation.

Third-Party Libraries

• Developed and maintained by external organizations or communities;
• Not included in the JDK; you add them to your project using tools like Maven;
• Examples include junit-jupiter for testing and javaparser-core for code analysis;
• Help you solve specific problems without reinventing the wheel.

Frameworks

• Collections of libraries that provide a structure for building applications;
• Often define application architecture and control the flow of your code ("inversion of control");
• Examples include Spring and Hibernate (not included in this course's available libraries);
• Offer reusable components and best practices for building large, maintainable systems.