String vs StringBuilder vs StringBuffer in Java | Immutability & Thread Safety Explained
Understanding the difference between String, StringBuffer, and StringBuilder in Java is one of the most common interview topics—and also one of the most misunderstood concepts even among experienced developers.
These three classes look similar, they all deal with text, and their methods often appear identical… but their internal behavior, performance impact, and thread-safety characteristics are completely different.
In this video, I break down all three using three simple and practical pillars that remove all confusion:
✅ Mutability – how each class handles changes to text
✅ Memory – how the String Pool, Heap, and literals actually work internally
✅ Thread Safety – when synchronization matters and how it affects performance
By the end, you’ll have complete clarity on which one to use, why Java created three separate classes, and how their internal design impacts interviews, performance, and real-world coding.
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