difference between StringBuffer and StringBuilder in Java

Both StringBuffer and StringBuilder in Java are used for the same purpose: to create and manipulate mutable sequences of characters. The main difference between them lies in their synchronization behavior:

StringBuffer:

1. Thread-Safe:
   • StringBuffer is synchronized, which means it is thread-safe. Multiple threads can safely use StringBuffer without external synchronization.
2. Slower Performance in Multithreaded Environments:
   • Because of synchronization, StringBuffer can be slower than StringBuilder, especially in multithreaded environments, where synchronization can lead to overhead.
3. Usage:
   • Use StringBuffer when you need a mutable sequence of characters, and your code is running in a multithreaded environment.

Example using StringBuffer:

/*
 * Author: Zameer Ali Mohil
 * */
public class StringBufferExample {
    public static void main(String[] args) {
        StringBuffer buffer = new StringBuffer("Hello");
        buffer.append(" World"); // Modifies the same StringBuffer object
        System.out.println(buffer);
    }
}

StringBuilder:

1. Not Thread-Safe:
   • StringBuilder is not synchronized, which means it is not thread-safe. Multiple threads should not access a StringBuilder instance concurrently without proper synchronization.
2. Faster Performance in Single-Threaded Environments:
   • Because it lacks synchronization, StringBuilder can be faster than StringBuffer, especially in single-threaded environments.
3. Usage:
   • Use StringBuilder when you need a mutable sequence of characters and you are sure that your code will be used in a single-threaded environment, or you will handle synchronization explicitly.

Example using StringBuilder:

/*
 * Author: Zameer Ali Mohil
 * */
public class StringBuilderExample {
    public static void main(String[] args) {
        StringBuilder builder = new StringBuilder("Hello");
        builder.append(" World"); // Modifies the same StringBuilder object
        System.out.println(builder);
    }
}

In both examples, append() is used to modify the content of the StringBuffer and StringBuilder objects. However, it’s important to note that if these examples were run concurrently by multiple threads, you might encounter issues with StringBuffer if synchronization is not handled properly. In such cases, using StringBuilder in a single-threaded environment or handling synchronization manually might be a better choice for improved performance.

Both StringBuffer and StringBuilder are classes in Java that allow you to create mutable sequences of characters. The choice between them depends on your specific use case: use StringBuffer when thread safety is necessary, and use StringBuilder when you are working in a single-threaded environment or can handle synchronization manually.