02 Strings

A Java String contains an immutable sequence of Unicode characters. Unlike C/C++, where string is simply an array of char, A Java String is an object of the class java.lang.

Java String is, however, special. Unlike an ordinary class:

• String is associated with string literal in the form of double-quoted texts such as "Hello, world!". You can assign a string literal directly into a String variable, instead of calling the constructor to create a String instance.
• The '+' operator is overloaded to concatenate two String operands. '+' does not work on any other objects such as Point and Circle.
• String is immutable. That is, its content cannot be modified once it is created. For example, the method toUpperCase() constructs and returns a new String instead of modifying the its existing content.