[工学]an introduction to java application

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1、AnIntroductiontoJavaApplicationYaoxiaolingTopicOurFirstjavaProgramOutputstatementsVariableInputstatementsArithmeticoperatorsMemoryDecision-makingstatementsRelationalandequalityoperatorsOurfirstjavaProgramTextout“Welcometojavaprogramming”TalkingWhatwaswrongwithyourprogram?Whatwillyoudoifwew

2、anttoeditandrunourjavaprogram?Whatisfunctionofyourprogram?EditjavaprograminnotepadpublicclassMessage{/***这是一个main方法。*/publicstaticvoidmain(String[]args){/*输出此消息*/System.out.println("欢迎来到Java世界！");}}演示编辑和保存Java程序……依次选择程序附件记事本单击开始编译和运行Displayhowtocompileandrunjavaprogram……单击开始进入程序所保存的目录依次选

3、择程序->附件->命令提示符编译JavacMessage.java运行javaMessage输出结果BeforeyoubeginWeneedJavadevelopmentEnvironmentJ2SEDevelopmentkithttp://java.sun.com/javase/downloads/index.jspEditornotepadeditplusUltraEditIDEJcreatorEclipseNetBeanLetusinstallJDKhttp://java.sun.com/javase/downloads/index.jspJDKEnvironment

4、Javadirectoriesbin:executablefilessuchasjava.exejavac.exelib：javalibraryclassesfiles.include：localfiles.demo：displayprograms.jre：javarunningenvironmentAfterweinstalledjdk….SettingenvironmentalvariablesPathvariableClasspathvariableSettingthePathVariable选择高级SettingtheclasspathVariable选择高级cla

5、sspathC:ProgramFilesJavajdk1.6.0_13libdt.jar;C:ProgramFilesJavajdk1.6.0_13libtools.jar;Whatthefunctionofourprogram?OutputaliteralwordWelcometojavaprogaramming.WhatwelearnfromthisprogramJavaprogramstructureOutputstatementjavaprogramstructuresourcefile,class,method,statementPutacla

6、ssinasourcefilePutmethodsinaclassPutstatementsinamethodOurfirstjavaprogramWhatgoesinasourcefile?Whatgoesinaclassfiles?Whatgoesinamethodfiles?publicclassWelcome1{}Classpublicstaticvoidmain(Stringargs[]){}methodSystem.out.println(“Welcometojavaprogramming”);statementsReadingtimecommentCommen

7、tisusedtoenhanceyourprogramreadabilityQuestions:HowmanykindsofcommentmethodsdoesJavaprovided?Tellusdifferenceamongthesecomments?Classclassisalogicalunitofjavaprogram.Questions:Howshouldwedeclareaclass?Howshouldwenamealegalidentifier?Whatisagoodclassname?Howsho