How do Strings compare to StringBuffer and StringBuilder in terms of mutability?

• A. Strings are mutable
• B. StringBuffer is mutable
• C. Strings are immutable
• D. StringBuilder is immutable

Answer: (C)

Strings in Java are immutable, meaning that once they are created, their value cannot be changed. Any operation that appears to modify a String actually creates a new String object. This characteristic ensures that Strings can be shared safely across different parts of a program without risking unintended modifications, which is particularly important in concurrent programming and when working with collections.

On the other hand, both StringBuffer and StringBuilder are mutable, meaning that you can change their contents without creating a new object. This behavior allows for more efficient manipulation of text, especially in scenarios where numerous modifications (like appending, deleting, or inserting characters) are required. StringBuffer is synchronized, making it thread-safe, which means it can be safely used in multi-threaded environments, while StringBuilder is not synchronized, making it faster and more suitable for single-threaded tasks.

Understanding this distinction between mutability in Strings, StringBuffer, and StringBuilder is key for efficient string manipulation in Java programming.