Becoming popular in the early 1990s and the norm today, object-oriented programming (OOP) languages, such as C++ and Java ... "classes," and one instance of a class is an "object." For example ...

An abstract class is a template definition of methods and variables in a specific class, or category of objects. In programming ... Implementation is done similarly in Java. For example, using the ...

as in the following example. String s1 = new String("Hello world!"); That code will create an s1 string object and a reference variable. As noted, Java strings are immutable. Once created, a string ...