Compare String, StringBuilder, and StringBuffer in Java
Company: Apple
Role: Software Engineer
Category: Software Engineering Fundamentals
Difficulty: medium
Interview Round: Technical Screen
Compare String with StringBuilder in Java, including mutability and repeated text construction. Also explain where StringBuffer fits and whether these mutable types are safe to share across threads.
### What a Strong Answer Covers
Distinguish changing a reference from changing an object, identify the synchronization difference correctly, and discuss why individually synchronized operations do not automatically make a multi-step action atomic.
### Follow-up Questions
- Why can repeated concatenation in a loop be costly?
- When is a method-local builder preferable to sharing a mutable text buffer?
Overview: Compare immutable strings with mutable Java text builders and buffers. Correctly identify synchronization guarantees and reason about repeated construction, thread confinement, and compound operations.
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