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| • The three basic components of a Java program are comments, import
statements, and class declarations. • AJava program must have one class designated as the main class. The designated main class must have the main method. • An object must be declared and created before we can use it. • Tocommand an object or a class to perform a task, we send a message to it. We use the expression calling a method synonymously with sending a message. • Asingle name can be used to refer to different objects (of the same class) at different times. An object with no reference will be returned to a system. • We follow the edit-compile-run cycle to execute programs. • Asource file is compiled into a bytecode file by a Java compiler. • AJava interpreter (also called a Java Virtual Machine) executes the bytecode. • The standard classes introduced in this chapter are: JFrame SimpleDateFormat JOptionPane String Date • Table 2.2 lists the Java naming convention.  |