When should you prefer immutability and when should you avoid it?

Immutability refers to an object's inability to be modified after it has been created. In Java, using immutable objects has several advantages, but there are also scenarios where mutable objects are preferred. Understanding when to use immutability can significantly impact the design and performance of your applications.

When to Prefer Immutability

• Thread Safety: Immutable objects are inherently thread-safe because their state cannot change. This is particularly useful in multi-threaded applications.
• Hashing and Caching: If you use objects as keys in a hash table, immutability ensures that their hash code remains constant, thus preventing issues when the object is used in different contexts.
• Ease of Maintenance: Immutability can lead to simpler code that is easier to understand, maintain, and debug, as you don’t have to track changes over time.
• Functional Programming: Immutability fits well with functional programming paradigms, leading to more predictable and less error-prone code.

When to Avoid Immutability

• Performance Concerns: Creating new instances of immutable objects instead of modifying existing ones can lead to increased memory usage and CPU overhead.
• Complex State Management: In cases where objects undergo frequent changes, such as in real-time applications (e.g., gaming, UI), mutable objects may simplify state management.
• Large Data Structures: When dealing with large collections or data structures, the overhead of creating new instances can be costly.