| Feature | String | StringBuilder | StringBuffer |
|---|---|---|---|
| Introduction | JDK 1 | JDK 5 | JDK 1 |
| Mutability | Immutable | Mutable | Mutable |
| Thread Safety | Thread safe | Not Thread safe | Thread safe |
| Memory Efficiency | High | Efficient | Less Efficient |
| Performance | High(No synchronisation) | High (No synchronisation) | Low(Due to synchronisation) |
| Usage | It is used when we want immutability. | This is used when thread safety is not required. | This is used when thread safety is required. |
StringBuilder:- If you are working in single thread environment and you want high performance in that case you can use StringBuilder class of java which was introduced in JDK1.5.
StringBuffer:- If you are working in MultiThreaded environment and need thread safety guarantee than StringBuffer would be more appropriate despite of slight thread overhead. StringBuffer was introduced in JDK1.1.
