Strings, which are widely used in Java programming, are a sequence of characters. In the Java programming language, strings are objects. The String class represents character strings. All string literals in Java programs, such as “abc”, are implemented as instances of this class.
The String class is immutable, so that once it is created a String object cannot be changed. If there is a necessity to make a lot of modifications to Strings of characters, then you should use String Buffer & String Builder Classes.
The class String includes methods for examining individual characters of the sequence, for comparing strings, for searching strings, for extracting substrings, and for creating a copy of a string with all characters translated to uppercase or to lowercase. Case mapping is based on the Unicode Standard.