Introduction to Programming

Expressions

As we said at the beginning of this section, an expression exists only as a part of a statement, the latter being the complete action (we will discuss it in the next subsection). This means that an expression can be a building block of an action. Some expressions can even become a full action (an expression statement) after adding a semicolon to them. 

The distinguishing feature of an expression is that it can be evaluated, which means it can produce something as the result of its execution. This something can be one of three things:

• A variable, such as i = 2
• A value, such as 2*2
• Nothing, when the expression is an invocation of a method that returns nothing (void). Such an expression can only be the full action—an expression ...