java 知识点总结.ppt

java知识点总结 The WhitePaper Buzzwords Simple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 JVMJavaVirtualMachineJDKJavaDevelopmentKitJREJavaRuntimeEnvironmentIDEIntegratedDevelopmentEnvironment集成开发环境GUIGraphicalUserInterfaceApplicationvs Applet enumtypeenumSize SMALL MEDIUM LARGE EXTRA LARGE Sizes Size MEDIUM stringStringgreeting Hello Strings greeting substring 1 3 StringBuilderbuilder newStringBuilder builder append a builder append cat StringcompletedString 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 println 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 Astaticfinalfieldisasharedconstantacrossallitsobjects commentMulti linecomments likethis Documentationcomments ThisisthefirstsampleprograminCoreJavaChapter3 version1 011997 03 22 authorGaryCornell Literalshex0 xCAFEoctal031Binary0b1111 0100 0010 0100 0000Double POSTIVE INFINITY正无穷大Double NEGATIVE INFINITY负无穷大 UsesupertoavoidrecursivecallpublicclassManagerextendsEmployee privatedoublebonus publicdoublegetSalary returnsuper getSalary bonus Object TheCosmicSuperclassAnyobjectorarrayreferencecanbestoredinavariableoftypeObject System out println Employee obj1 getName Objectobj2 newint 10 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 SpecialobjectsIntegerDouble LambdaArrays sort intArr newComparator publicintcompare Integeri Integerj returnj i Arrays sort stus s1 s2 s2 getName compareTo s1 getName System out println Arrays toString stus ComparatorArrays sort stus newComparator publicintcompare Students1 Students2 returns2 getName compareTo s1 getName ScreenSizeDimensionscreenSize Toolkit getDefaultToolkit getScreenSize Resizable drawDrawLineDrawRectDrawOval LayoutFlowLayoutThedefaultlayoutofJPanelBorderLayoutThedefaultlayoutofJFrameGridLayout ScrollPaneJScrollPanescrollPane newJScrollPane textArea setbackgroundcolorbRed addActionListener e getContentPane setBackground Color red bPanel setBackground Color red ChangefontActionListenercheckbListener event intmode 0 if bold isSelected mode Font BOLD if italic isSelected mode Font ITALIC label setFont newFont Serif mode FONTSIZE CombpBoxJComboBoxfaceCombo newJComboBox faceCombo addItem Serif faceCombo addItem SansSerif faceCombo addItem Monospaced faceCombo addItem Dialog faceCombo addItem DialogInput faceCombo addActionListener event label setFont newFont String faceCombo getSelectedItem Font PLAIN 24 menubarsetJMenuBar toolbarJToolBarbar newJToolBar DefineabuttonwithagiveniconJButtonbtnRed newJButton newImageIcon red ball gif SpecifytheactionbtnRed addActionListener e label setForeground Color red Addthebuttontothebarbar add btnRed MessageDialog JOptionPane showMessageDialog null HellotheDialogWorld ConfirmDialog ReturnsanintegerindicatingtheoptionselectedbytheuserYes 0No 1Cancel 2Close 1 intretConfirm JOptionPane showConfirm