Chapter 2. Java Syntax from the Ground Up

This chapter is a terse but comprehensive introduction to Java syntax. It is written primarily for readers who are new to the language but have at least some previous programming experience. Determined novices with no prior programming experience may also find it useful. If you already know Java, you should find it a useful language reference. The chapter includes comparisons of Java to C and C++ for the benefit of programmers coming from those languages.

This chapter documents the syntax of Java programs by starting at the very lowest level of Java syntax and building from there, covering increasingly higher orders of structure. It covers:

• The characters used to write Java programs and the encoding of those characters.

• Literal values, identifiers, and other tokens that comprise a Java program.

• The data types that Java can manipulate.

• The operators used in Java to group individual tokens into larger expressions.

• Statements, which group expressions and other statements to form logical chunks of Java code.

• Methods (also called functions, procedures, or subroutines), which are named collections of Java statements that can be invoked by other Java code.

• Classes, which are collections of methods and fields. Classes are the central program element in Java and form the basis for object-oriented programming. Chapter 3 is devoted entirely to a discussion of classes and objects.

• Packages, which are collections of related classes.

• Java programs, which consist of one or more interacting classes that may be drawn from one or more packages.

The syntax of most programming languages is complex, and Java is no exception. In general, it is not possible to document all elements of a language without referring to other elements that have not yet been discussed. For example, it is not really possible to explain in a meaningful way the operators and statements supported by Java without referring to objects. But it is also not possible to document objects thoroughly without referring to the operators and statements of the language. The process of learning Java, or any language, is therefore an iterative one. If you are new to Java (or a Java-style programming language), you may find that you benefit greatly from working through this chapter and the next twice, so that you can grasp the interrelated concepts.