StringBuffer vs. StringBuilder: Key Differences | Generated by AI
1. Thread Safety
- StringBuffer: Thread-safe (synchronized). Multiple threads can safely access it simultaneously without data corruption
- StringBuilder: Not thread-safe. Should only be used in single-threaded environments
2. Performance
- StringBuffer: Slower due to synchronization overhead. Each method call acquires and releases locks
- StringBuilder: Faster (10-15% or more) because it has no synchronization overhead
3. When to Use
StringBuffer:
- Multi-threaded applications where the same instance is accessed by multiple threads
- When thread safety is a requirement
- Legacy code that hasn’t been updated
StringBuilder:
- Single-threaded applications (most common scenario)
- Local variables within methods (not shared between threads)
- Modern Java applications where performance matters
4. Synchronization Details
- StringBuffer: All methods are synchronized using the
synchronizedkeyword - StringBuilder: No synchronization, methods are not synchronized
5. Introduction
- StringBuffer: Available since Java 1.0
- StringBuilder: Introduced in Java 5 (2004) as a faster alternative
6. Memory and Method Behavior
Both classes share the same API and methods (append, insert, delete, reverse, etc.) and have identical functionality except for synchronization.
Code Example
// StringBuilder - faster for single-threaded use
StringBuilder sb = new StringBuilder();
sb.append("Hello");
sb.append(" World");
// StringBuffer - safer for multi-threaded use
StringBuffer sbf = new StringBuffer();
sbf.append("Thread");
sbf.append(" Safe");
Best Practice
Use StringBuilder by default unless you specifically need thread safety, in which case use StringBuffer or external synchronization with StringBuilder.