Spring vs guava: What are the differences?

# Introduction
When considering software development in Java, two popular libraries that often come into conversation are Spring and Guava. While both provide useful utilities and functionalities, they serve different purposes in the Java ecosystem.

## 1. **Dependency Injection**:
Spring is commonly used for its robust dependency injection framework, allowing developers to easily manage dependencies and facilitate the creation of loosely coupled components. On the other hand, Guava does not focus on dependency injection as a primary feature, but rather provides various utilities for common programming tasks.

## 2. **Collection Utilities**:
Guava offers a rich set of utilities for working with collections, including immutable collections, additional collection types, and powerful filtering methods. In contrast, Spring's primary focus is not on collection manipulation, and it typically leverages Java's core collection APIs for such tasks.

## 3. **Concurrency**:
Guava provides helpful utilities for concurrent programming, such as ListenableFuture and various concurrency primitives. In comparison, while Spring offers support for managing concurrency using features like @Async, its primary focus is on providing enterprise application development tools.

## 4. **Functional Programming**:
Guava includes support for functional programming paradigms through its Function and Predicate interfaces, enabling developers to write more expressive and concise code. Spring, while not opposed to functional programming, does not emphasize it as heavily as Guava.

## 5. **Error Handling**:
Spring offers a wide range of error handling and exception management mechanisms, including declarative transaction management and robust support for AOP-based error handling. Guava, while providing utilities for common error handling tasks, does not have the same level of sophistication in this area as Spring.

## 6. **Community and Support**:
Spring has a large and active community, which contributes to its vast ecosystem of libraries, tools, and resources. Guava, while widely used and respected, may not have the same level of community support and resources as Spring.

In Summary, Spring and Guava differ in their primary focus areas, with Spring excelling in enterprise application development tools, dependency injection, and error handling, while Guava shines in collection utilities, concurrency, functional programming, and community support.