Storage area: In string, the String pool serves as the storage area. For StringBuilder and StringBuffer, heap memory is the storage area.
Mutability: A String is immutable, whereas both the StringBuilder and StringBuffer are mutable.
Efficiency: It is quite slow to work with a String. However, StringBuilder is the fastest in performing operations. The speed of a StringBuffer is more than a String and less than a StringBuilder. (For example appending a character is fastest in StringBuilder and very slow in String because a new memory is required for the new String with appended character.)
Thread-safe: In the case of a threaded environment, StringBuilder and StringBuffer are used whereas a String is not used. However, StringBuilder is suitable for an environment with a single thread, and a StringBuffer is suitable for multiple threads.
Syntax:
// String
String first = "InterviewBit";
String second = new String("InterviewBit");
// StringBuffer
StringBuffer third = new StringBuffer("InterviewBit");
// StringBuilder
StringBuilder fourth = new StringBuilder("InterviewBit");