Difference between Stringbuilder and Stringbuffer in Java

StringBuffer and StringBuilder are classes in Java that are similar to the String class, but they are mutable, which means that their values can be modified after they are created. They are used to build strings efficiently by appending, inserting, or deleting characters.

Here is an example of how to use StringBuffer:

StringBuffer sb = new StringBuffer();
sb.append("Hello");
sb.append(", ");
sb.append("World");
sb.append("!");

System.out.println(sb.toString());  // prints "Hello, World!"

Here is an example of how to use StringBuilder:

StringBuilder sb = new StringBuilder();
sb.append("Hello");
sb.append(", ");
sb.append("World");
sb.append("!");

System.out.println(sb.toString());  // prints "Hello, World!"

The main difference between StringBuffer and StringBuilder is that StringBuffer is thread-safe, which means that it can be used safely in multi-threaded environments, while StringBuilder is not thread-safe. This means that StringBuffer may be slightly slower than StringBuilder, but it is generally safer to use in concurrent applications.

Both StringBuffer and StringBuilder provide methods for modifying the contents of the string, such as insert(), delete(), and replace(). They also provide methods for converting the string to other data types, such as toLowerCase() and toUpperCase().

It's worth noting that the String class is generally preferred over StringBuffer and StringBuilder unless you need the mutability or the thread-safety of these classes. The String class is heavily optimized for performance and is generally faster and more efficient to use.