In C, strings are not first-class types; a string is really just a null-terminated array of characters.
C++ inherits the same type from C, and also adds a class type std::string from its class library.
Strings in Java are not null-terminated arrays of characters, as in C/C++. Instead, they are instances of the Java String class. In other words, Strings are fully-fledged objects.
This is also true for string literals like “Hello world!”. Each string literal is an object of type String.
Java defines an operator (+) that allows for concatenation of strings and other types.
Note: Objects of type String are immutable.
If you want to change the contents of a string, you must either change the reference to the string, or use objects of type StringBuffer.
(More later about String and StringBuffer)