Difference between StringBuilder and StringBuffer

The StringBuilder and StringBuffer classes in Java are used to create mutable strings. A mutable string is a string that can be modified after it is created, unlike a regular string, which is immutable and cannot be modified.

The main difference between StringBuilder and StringBuffer is that StringBuilder is not thread-safe, while StringBuffer is thread-safe. This means that StringBuilder is faster than StringBuffer because it doesn't have to perform synchronization to ensure thread safety. However, StringBuffer is safer to use in a multi-threaded environment because it ensures that only one thread can access it at a time.

Here are some other differences between StringBuilder and StringBuffer:

  • StringBuilder was introduced in Java 5, while StringBuffer has been a part of the Java platform since the beginning.
  • StringBuilder is implemented using an array of characters, while StringBuffer is implemented using a char[] array and a synchronized block.
  • StringBuilder has a capacity of 16 characters by default, while StringBuffer has a capacity of 16 characters plus the length of the string it contains.
  • StringBuilder has the append(), insert(), delete(), and replace() methods, which allow you to modify the contents of the string. StringBuffer has the same methods, but they are all synchronized to ensure thread safety.

In general, you should use StringBuilder unless you need thread-safety or you are working in a multi-threaded environment. In such cases, you should use StringBuffer.

Here's an example of how to use StringBuilder:

StringBuilder sb = new StringBuilder();
sb.append(" ");
String str = sb.toString();

This will create a StringBuilder object and append the strings "Hello", " ", and "World" to it. The toString() method is then used to convert the StringBuilder to a regular string.