Building Strings in Java: String vs StringBuffer Performance Comparison (With Real Benchmark)

In this detailed Java tutorial, we compare String vs StringBuffer when building sentences dynamically. Many developers still use the + operator inside loops — but did you know it can cause serious performance issues? In this video, we: ✔ Build a sentence dynamically using normal String ✔ Build the same sentence using StringBuffer.append() ✔ Measure execution time using System.nanoTime() ✔ Analyze time complexity (O(n²) vs O(n)) ✔ Explain internal memory behavior ✔ Understand why StringBuffer is more efficient Key Concepts Covered: • String immutability • Object creation overhead • append() time complexity • Internal char[] resizing • Amortized O(1) explanation • Garbage collection impact Interview Insight: Using String in loops leads to O(n²) complexity, while StringBuffer operates in O(n) overall time. #Java #String #StringBuffer #JavaPerformance #JavaInterviewQuestions #MutableVsImmutable #CodingTips #JavaTutorial #BigO #AnalystAdda