java 知识点总结.ppt

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1、java知识点总结The“WhitePaper”BuzzwordsSimple简洁Object-Oriented面向对象的Distributed分布式（对网络文件处理）Robust健壮性（可靠性，减少程序错误）Secure安全性（沙盒）Architecture-neutral结构中立（JVM，WORA)Portable可移植Interpreted解释型High-performance高效性Multithreaded并发性Dynamic动态性JVMJavaVirtualMachineJDKJavaDevelopmentKitJREJavaRuntimeEnvironmentIDEInt

2、egratedDevelopmentEnvironment集成开发环境GUIGraphical User InterfaceApplicationvs.AppletenumtypeenumSize{SMALL,MEDIUM,LARGE,EXTRA_LARGE};Sizes=Size.MEDIUM;stringStringgreeting="Hello";Strings=greeting.substring(1,3);StringBuilderbuilder=newStringBuilder();builder.append(‘a’);builder.append(“cat”);Str

3、ingcompletedString=builder.toString();PredefinedclassDateb_day=newDate();System.out.println(b_day);//gettheyearSystem.out.println(b_day.getYear());System.out.println(b_day.getMonth());......factorymethodsLocalDaterightNow=LocalDate.now();LocalDatenewYearsEve=LocalDate.of(2017,9,25);System.out.p

4、rintln(rightDate.getYear());System.out.println(rightDate.getMonthValue());System.out.println(rightDate.getDayOfMonth());Specialfinal只生成一次static:Astaticfieldisalsocalledaclassfield,whichmeansthatthestaticfieldissharedacrossallitsobjects.只保存最近赋值，所有对象通用,类似unionstaticfinal:A staticfinal fieldisasha

5、redconstantacrossallitsobjectscommentMulti-linecomments:/*likethis...*/Documentationcomments:/***ThisisthefirstsampleprograminCoreJavaChapter3*@version1.011997-03-22*@authorGaryCornell*/Literalshex0xCAFEoctal031Binary0b1111_0100_0010_0100_0000Double.POSTIVE_INFINITY正无穷大Double.NEGATIVE_INFINITY负

6、无穷大Use super toavoidrecursivecallpublicclassManagerextendsEmployee{privatedoublebonus;publicdoublegetSalary(){returnsuper.getSalary()+bonus;}}Object:TheCosmicSuperclassAnyobjectorarrayreferencecanbestoredinavariableoftype Object:System.out.println(((Employee)obj1).getName());Objectobj2=newint[1

7、0];((int[])obj2)[0]=1;System.out.println(((int[])obj2)[0]);ArrayListArrayListeList=newArrayList<>();eList.add(LiLei);//PrintthesecondoneSystem.out.println(eList.get(1));//SetthesecondtoJerryeList.set(1,Jerry);Specialobje