In this lecture we will concentrate on Java syntax and form.

• Syntax displays - concise way of expressing language rules.
  • Format for syntax displays:
    • Form section gives the rule
    • Example section gives a concrete example of the rule
    • Interpretation section explains implications of the rule.

  • A syntax display for the class definition:

    Form: [visibility] class class-name [extends parent] { ... }
    Example: public class PieceOfFabric extends SimpleGUI { ... }
    Interpretation: The visibility of class-name may be specified as public or private.

  • Other details about syntax display notation:
    • Items in square brackets ([ ]) are optional.
    • Items in italics must be replaced by specific values.
    • The { ... } means a sequence of Java statements enclosed by curly braces.

  • Syntax diagram for method definition:

    Form: [visibility] resultType methodName ([argumentList]) { ... }
    Example: public int vectorLength(int x, int y) { ...}
    Interpretation: Method methodName returns a value of type resultType.
    

• Identifiers: (See rules on Page 50 of textbook.)
  • Begin with letter, underscore (_), or $.
  • Only has letters, digits, underscore, $.
  • Not a Java reserved word. (The reserved words are displayed by Java WorkShop in light blue so you can tell when you writing your program.)
  • Case sensitive.
  • No length restriction.

• Primitive types:
  • integers (int, byte, short, long)
  • reals (double, float)
  • logical (boolean) has values true and false
  • character (char).