Anatomy of a Java Program Comments Reserved words

a) Comments ignored during program execution Include a summary at the beginning of the

b) Reserved Words that have a specific meaning to the compiler Cannot be used

c) Modifiers Java uses certain reserved words called modifiers that specify the properties of

d) Statements A statement represents an action or a sequence of actions. The statement

e) Blocks A pair of braces in a program forms a block that groups

f) Classes The class is the essential Java construct. A class is a template

g) Method System. out. println is a method. Method is a collection of statements

h) main () Method The main method provides the control of program flow. The

Programming Style and Documentation in Java a) Appropriate comments and comments style Include a

Comments Style A “block” comment is placed between /* and */ marks: /* Exercise

Javadoc Comments (cont’d) /** indicates a javadoc comment /** * * */ Returns total

b) Naming Conventions Choose meaningful and descriptive names. Variables and method names: Use lowercase.

Cont. . Class names: Capitalize the first letter of each word in the name.

c) Proper Indentation and Spacing Indentation Indent two spaces. Spacing Use blank line to

d) Block Styles Use end-of-line style for braces. 16

Slides: 16

Download presentation

Anatomy of a Java Program Comments Reserved words Modifiers Statements Blocks Classes Methods The main method 1

a) Comments ignored during program execution Include a summary at the beginning of the program to explain what the program does, its key features, its supporting data structures, and any unique techniques it uses. Comments start with: // Traditional comments: /*. . . */

b) Reserved Words that have a specific meaning to the compiler Cannot be used for other purposes in the program. Key words examples are: • boolean • public • void • private • continue • class • int • protected • return • static • double • package Key words are lower case (Java is a case sensitive language). goto and const are C++ keywords, but not currently used in Java. If they appear in Java, Java compilers will produce error messages.

c) Modifiers Java uses certain reserved words called modifiers that specify the properties of the data, methods, and classes and how they can be used. Examples of modifiers are public and static. Other modifiers are private, final, abstract, and protected. A public datum, method, or class can be accessed by other programs. A private datum or method cannot be accessed by other programs.

d) Statements A statement represents an action or a sequence of actions. The statement System. out. println("Welcome to Java!") in the program is a statement to display the greeting "Welcome to Java!" Every statement in Java ends with a semicolon (; ).

e) Blocks A pair of braces in a program forms a block that groups components of a program.

f) Classes The class is the essential Java construct. A class is a template or blueprint for objects. To program in Java, you must understand classes and be able to write and use them. A program is defined by using one or more classes.

g) Method System. out. println is a method. Method is a collection of statements that performs a sequence of operations to display a message on the console. It is used by invoking a statement with a string argument. The string argument is enclosed within parentheses. In this case, the argument is "Welcome to Java!" You can call the same println method with a different argument to print a different message.

h) main () Method The main method provides the control of program flow. The Java interpreter executes the application by invoking the main method. The main method looks like this: public static void main(String[] args) { // Statements; }

Programming Style and Documentation in Java a) Appropriate comments and comments style Include a summary at the beginning of the program to explain what the program does, its key features, its supporting data structures, and any unique techniques it uses. Include your name, class, lecture’s name, date, and a brief description of your code at the beginning of the program.

Comments Style A “block” comment is placed between /* and */ marks: /* Exercise 5 -2 for Java Methods Author: Miss Brace Date: 3/5/2010 Rev. 1. 0 */ A single-line comment goes from // to the end of the line: weight *= 2. 2046; // Convert to kilograms

Javadoc Comments (cont’d) /** indicates a javadoc comment /** * * */ Returns total sales from all vendors; sets <code>total. Sales</code> to 0. @return total amount of sales from all vendors Common style Can use HTML tags

b) Naming Conventions Choose meaningful and descriptive names. Variables and method names: Use lowercase. If the name consists of several words, concatenate all in one, use lowercase for the first word, and capitalize the first letter of each subsequent word in the name. For example, the variables radius and area, and the method compute. Area.

Cont. . Class names: Capitalize the first letter of each word in the name. For example, the class name Compute. Area. Constants: Capitalize all letters in constants, and use underscores to connect words. For example, the constant PI and MAX_VALUE

c) Proper Indentation and Spacing Indentation Indent two spaces. Spacing Use blank line to separate segments of the code. 15

d) Block Styles Use end-of-line style for braces. 16