StringBuilder and StringBuffer

Explain the difference between StringBuilder and StringBuffer classes.

StringBuilder and StringBuffer are both classes in Java that provide mutable sequences of characters, allowing for efficient manipulation of strings. However, they differ in terms of their synchronization behavior and performance characteristics.

1. StringBuilder: StringBuilder was introduced in Java 5 as part of the Java API. It is a non-synchronized, mutable sequence of characters. This means that StringBuilder is not thread-safe, making it more efficient in single-threaded environments but potentially unsafe in multi-threaded scenarios.

Key Features of StringBuilder:

  • Non-synchronized: StringBuilder methods are not synchronized, which means they are not thread-safe.
  • Mutable: StringBuilder allows for the modification of its contents, such as appending, inserting, deleting, or replacing characters.
  • Better Performance: Due to its non-synchronized nature, StringBuilder typically offers better performance than StringBuffer.

Example of StringBuilder:

javaCopy codeStringBuilder sb = new StringBuilder("Hello");
sb.append(" World");
System.out.println(sb.toString()); // Output: Hello World


2. StringBuffer: StringBuffer is an older class that has been available since the early versions of Java. It is also a mutable sequence of characters, but unlike StringBuilder, StringBuffer is synchronized, making it thread-safe.

Key Features of StringBuffer:

  • Synchronized: StringBuffer methods are synchronized, ensuring thread safety in multi-threaded environments.
  • Mutable: Similar to StringBuilder, StringBuffer allows for the modification of its contents.
  • Slower Performance: Due to its synchronized nature, StringBuffer may have slightly slower performance compared to StringBuilder, especially in single-threaded scenarios.

Example of StringBuffer:

javaCopy codeStringBuffer sb = new StringBuffer("Hello");
sb.append(" World");
System.out.println(sb.toString()); // Output: Hello World


Choosing Between StringBuilder and StringBuffer:

  • Use StringBuilder when you are working in a single-threaded environment or when thread safety is not a concern. It offers better performance due to its non-synchronized nature.
  • Use StringBuffer when you are working in a multi-threaded environment and require thread safety. It ensures that operations on the string buffer are synchronized, preventing data corruption in concurrent scenarios.

A comparison of StringBuilder and StringBuffer in tabular form:

In summary, the choice between StringBuilder and StringBuffer depends on the specific requirements of your application regarding thread safety and performance. While StringBuilder provides better performance in single-threaded scenarios, StringBuffer ensures thread safety at the cost of slightly slower performance.