Chapter 2 Primitives, Variables and Expressions
Primitives are the most basic data types in Java. Each Java primitive is stored in a memory location having a well-defined size (number of bytes). The amount of memory used for each type correlates directly with the range of values that each type can hold (recall Computational Devices).
Java variables are identifiers (names) that we can declare and use as shorthand notation to access values stored at a specific memory location, including memory that holds primitive data. These variables may be used to both read a value from memory as well as write a new value back to the same memory location.
Java expressions are combinations of values, variables, operators, and other subexpressions that evaluate to a new value. They are the building blocks of Java programs and are used to perform computations and make decisions.
In this section we will introduce the eight Java primitives, literal notation for primitive values that provide a way to write them directly in a program, variables that refer to memory locations where these values are stored, and simple expressions used to combine values and variables to produce new values. We will use the JShell program throughout this section, which gives us the ability to demonstrate concepts and test our knowledge, all interactively.
