What is the difference between String and String Buffer

by

?– a) String objects are constants and immutable whereas StringBuffer objects are not. b) String class supports constant strings whereas StringBuffer class supports growable and modifiable strings.

In Java, String and StringBuffer are both classes that represent sequences of characters, but there are key differences between them.

  1. Immutability:
    • String: Objects of the String class are immutable, meaning that once a String object is created, its value cannot be changed. If you perform any operation that appears to modify a String, it actually creates a new String object.
    • StringBuffer: Objects of the StringBuffer class, on the other hand, are mutable. You can modify the contents of a StringBuffer object without creating a new object.
  2. Performance:
    • String: Because String objects are immutable, concatenating or modifying strings using the + operator or concat method creates new String objects, which may lead to performance overhead in terms of memory usage and time complexity.
    • StringBuffer: StringBuffer is designed for situations where you need to perform a lot of modifications on a string. It uses a mutable buffer, so appending or modifying the contents is more efficient, especially in scenarios with frequent changes.
  3. Synchronization:
    • String: String objects are inherently thread-safe because they are immutable. Multiple threads can safely access and share String objects without the need for external synchronization.
    • StringBuffer: StringBuffer is synchronized, making it safe for use in multithreaded environments. However, this synchronization comes with a performance cost.

In summary, if you need an immutable string and don’t anticipate frequent modifications, then String is suitable. If you expect to perform a lot of modifications (concatenations, insertions, deletions) on a string, especially in a multithreaded environment, then StringBuffer is a better choice due to its mutability and synchronization capabilities. Keep in mind that since Java 5, the StringBuilder class is also available, and it is similar to StringBuffer but without synchronization, making it more suitable for single-threaded scenarios where performance is crucial.