How are Java class instances created and used?

"Once we have defined our class and its constructors, we can create and use instances of it. Just as with regular variables, we need to declare instances of a class by providing the type and a variable name. For example:\n\nStudent s = null;\n\nStudent t = null;\n\nBoth of these declarations are simply just reference variables. They may refer to an instance of the class Student, but we have initialized them to null. To make these variables refer to valid instances, we invoke a constructor by using the new keyword and providing arguments to the constructor.\n\nStudent s = new Student(\"Alan\", \"Turing\", 1234, 3.4);\n\nStudent t = new Student(\"Margaret\", \"Hamilton\", 4321, 3.9);\n\nThe process of creating a new instance by invoking a constructor is referred to as instantiation. Once instances have been instantiated, they can be used by invoking their methods via the dot operator. The dot operator is used to select a member variable (if public) or member method.\n\nSystem.out.println(s.getFormattedName());\n\nif(s.getGpa() < t.getGpa()) {\n\nSystem.out.println(t.getFirstName() + \" has a better GPA\");\n\n}"