midStrings
StringBuilder vs StringBuffer vs String.
Updated Apr 28, 2026
Short answer
String is immutable; StringBuilder is mutable/non-thread-safe; StringBuffer is mutable/thread-safe.
Deep explanation
Intermediate string problems test your ability to use frequency maps and sliding windows. String is immutable; StringBuilder is mutable/non-thread-safe; StringBuffer is mutable/thread-safe.
Real-world example
Search filters that ignore character order.
Common mistakes
- Inefficiently sorting strings for an anagram check when a frequency map is O(n).
Follow-up questions
- What is the time complexity of sorting?