© 2007 Lawrenceville PressSlide 1

Chapter 3Chapter 3

Classes and ObjectsClasses and ObjectsChapter 3Chapter 3

Classes and ObjectsClasses and Objects

© 2007 Lawrenceville PressSlide 2

Chapter 3Chapter 3

PackagePackageChapter 3Chapter 3

PackagePackage

© 2007 Lawrenceville PressSlide 3

Chapter 3Chapter 3

Application PackageApplication PackageChapter 3Chapter 3

Application PackageApplication Package

© 2007 Lawrenceville PressSlide 4

Chapter 3Chapter 3

A Java ApplicationA Java ApplicationChapter 3Chapter 3

A Java ApplicationA Java Application

package firstApplication

/**

* The Greeting class displays a greeting

*/

public class Greeting {

public static void main(String[] args) {

System.out.println("Hello,world!");

}

}

package namepackage name

commentcomment

class declarationclass declarationmethodmethod

statementstatement

© 2007 Lawrenceville PressSlide 5

Chapter 3Chapter 3

Executing a Java ApplicationExecuting a Java ApplicationChapter 3Chapter 3

Executing a Java ApplicationExecuting a Java Application

public class Greeting public static void System.out.printl }}

source codesource code

03 3b 84 01 ff f9 68 05 1a

bytecodbytecodee

...c cilbup Hello,world!...48 b3 30

compilercompiler JVMJVM

© 2007 Lawrenceville PressSlide 6

Chapter 3Chapter 3

Escape SequencesEscape SequencesChapter 3Chapter 3

Escape SequencesEscape Sequences

An escape sequence is a backslash (\) followed by a symbol that together represent a character.

Commonly used escape sequences:\n newline\t tab (8 spaces)\\ backslash\" double quotation mark

© 2007 Lawrenceville PressSlide 7

Chapter 3Chapter 3

The format() MethodThe format() MethodChapter 3Chapter 3

The format() MethodThe format() Method

A method in the System class

Used to control the way output is displayed

Requires a format string and an argument list

The format string specifier takes the form: %[alignment][width]s

For exampleSystem.out.format("%-6s %4s", "Test1", "90");displays:

Test1 90

© 2007 Lawrenceville PressSlide 8

Chapter 3Chapter 3

Code ConventionsCode ConventionsChapter 3Chapter 3

Code ConventionsCode Conventions

An introductory comment should begin a program.

Package names should begin with a lowercase letter and then an uppercase letter should begin each word within the name.

Class names should be nouns and begin with an uppercase letter and an uppercase letter should begin each word within the name.

A comment block should be included before each class.

© 2007 Lawrenceville PressSlide 9

Chapter 3Chapter 3

Code Conventions Code Conventions ((con'tcon't))

Chapter 3Chapter 3

Code Conventions Code Conventions ((con'tcon't))

Comments should not reiterate what is clear from the code.

Statements in a method should be indented.

An open curly brace ({) should be placed on the same line as the class or method declaration, and the closing curly brace (}) should be on a separate line and aligned with the class or method declaration.

© 2007 Lawrenceville PressSlide 10

Chapter 3Chapter 3

Flowchart SymbolsFlowchart SymbolsChapter 3Chapter 3

Flowchart SymbolsFlowchart Symbols

input/outputinput/outputstart/endstart/end

© 2007 Lawrenceville PressSlide 11

Chapter 3Chapter 3

The Triangle FlowchartThe Triangle FlowchartChapter 3Chapter 3

The Triangle FlowchartThe Triangle Flowchart