翻译文献-java 事件封装

外文原文JAVAEVENTSAREPARTOFTHEJAVAAWTABSTRACTWINDOWINGTOOLKITPACKAGEANEVENTISTHEWAYTHATTHEAWTCOMMUNICATESTOYOU,ASTHEPROGRAMMER,ANDTOOTHERJAVAAWTCOMPONENTSTHATSOMETHINGHASHAPPENEDTHATSOMETHINGCANBEINPUTFROMTHEUSERMOUSEMOVEMENTSORCLICKS,KEYPRESSES,CHANGESINTHESYSTEMENVIRONMENTAWINDOWOPENINGORCLOSING,THEWINDOWBEINGSCROLLEDUPORDOWN,ORAHOSTOFOTHERTHINGSTHATMIGHT,INSOMEWAY,BEINTERESTINGTOTHEOPERATIONOFTHEPROGRAMNOTEJAVASABSTRACTWINDOWINGTOOLKITISAPACKAGEOFCLASSESTHATIMPLEMENTSMOSTCOMMONUICOMPONENTS,SUCHASWINDOWS,BUTTONS,MENUS,ANDSOONITISALSOSPECIFICALLYTHEAWT,ANDNOTJAVA,THATGENERATESANDMANAGESEVENTSINOTHERWORDS,WHENEVERJUSTABOUTANYTHINGHAPPENSTOAJAVAAWTCOMPONENT,INCLUDINGANAPPLET,ANEVENTISGENERATEDSOMEEVENTSAREHANDLEDBYTHEAWTORBYTHEBROWSERWITHOUTYOURNEEDINGTODOANYTHINGPAINTMETHODS,FOREXAMPLE,AREGENERATEDANDHANDLEDBYTHEBROWSERALLYOUHAVETODOISTELLTHEAWTWHATYOUWANTPAINTEDWHENITGETSTOYOURPARTOFTHEWINDOWSOMEEVENTS,HOWEVERFOREXAMPLE,AMOUSECLICKINSIDETHEBOUNDARIESOFYOURAPPLETYOUMAYNEEDTOKNOWABOUTWRITINGYOURJAVAPROGRAMSTOHANDLETHESEKINDSOFEVENTSENABLESYOUTOGETINPUTFROMTHEUSERANDHAVEYOURAPPLETCHANGEITSBEHAVIORBASEDONTHATINPUTTODAY,YOULLLEARNABOUTMANAGINGSIMPLEEVENTS,INCLUDINGTHEFOLLOWINGBASICSNNMOUSECLICKSNNMOUSEMOVEMENTS,INCLUDINGMOUSEDRAGGINGNNKEYBOARDACTIONSYOULLALSOLEARNABOUTTHEHANDLEEVENTMETHOD,WHICHISTHEBASISFORCOLLECTING,HANDLING,ANDPASSINGONEVENTSOFALLKINDSFROMYOURAPPLETTOOTHERUICOMPONENTSINTHEWINDOWORINYOURAPPLETITSELFTOMORROW,YOULLLEARNHOWTOCOMBINEEVENTSWITHTHEAWTTOCREATEACOMPLETEINTERFACEFORYOURAPPLETMOUSECLICKSLETSSTARTWITHTHEMOSTCOMMONEVENTYOUMIGHTBEINTERESTEDINMOUSECLICKSMOUSECLICKEVENTSOCCURWHENYOURUSERCLICKSTHEMOUSESOMEWHEREINTHEBODYOFYOURAPPLETYOUCANINTERCEPTMOUSECLICKSTODOVERYSIMPLETHINGSFOREXAMPLE,TOTOGGLETHESOUNDONANDOFFINYOURAPPLET,TOMOVETOTHENEXTSLIDEINAPRESENTATION,ORTOCLEARTHESCREENANDSTARTOVERORYOUCANUSEMOUSECLICKSINCONJUNCTIONWITHMOUSEMOVEMENTSTOPERFORMMORECOMPLEXMOTIONSINSIDEYOURAPPLETMOUSEDOWNANDMOUSEUPWHENYOUCLICKTHEMOUSEONCE,THEAWTGENERATESTWOEVENTSAMOUSEDOWNEVENTWHENTHEMOUSEBUTTONISPRESSED,ANDAMOUSEUPEVENTWHENTHEBUTTONISRELEASEDWHYTWOINDIVIDUALEVENTSFORASINGLEMOUSEACTIONBECAUSEYOUMAYWANTTODODIFFERENTTHINGSFORTHE“DOWN”ANDTHE“UP”FOREXAMPLE,LOOKATAPULLDOWNMENUTHEMOUSEDOWNEXTENDSTHEMENU,ANDTHEMOUSEUPSELECTSANITEMWITHMOUSEDRAGSBETWEENBUTYOULLLEARNABOUTTHATONELATERIFYOUHAVEONLYONEEVENTFORBOTHACTIONSMOUSEUPANDMOUSEDOWN,YOUCANNOTIMPLEMENTTHATSORTOFUSERINTERACTIONHANDLINGMOUSEEVENTSINYOURAPPLETISEASYALLYOUHAVETODOISOVERRIDETHERIGHTMETHODDEFINITIONINYOURAPPLETTHATMETHODWILLBECALLEDWHENTHATPARTICULAREVENTOCCURSHERESANEXAMPLEOFTHEMETHODSIGNATUREFORAMOUSEDOWNEVENTPUBLICBOOLEANMOUSEDOWNEVENTEVT,INTX,INTYTHEMOUSEDOWNMETHODANDTHEMOUSEUPMETHODASWELLTAKESTHREEPARAMETERSTHEEVENTITSELFANDTHEXANDYCOORDINATESWHERETHEMOUSEDOWNORMOUSEUPEVENTOCCURREDTHEEVENTARGUMENTISANINSTANCEOFTHECLASSEVENTALLSYSTEMEVENTSGENERATEANINSTANCEOFTHEEVENTCLASS,WHICHCONTAINSINFORMATIONABOUTWHEREANDWHENTHEEVENTTOOKPLACE,THEKINDOFEVENTITIS,ANDOTHERINFORMATIONTHATYOUMIGHTWANTTOKNOWABOUTTHISEVENTSOMETIMESHAVINGAHANDLETOTHATEVENTOBJECTISUSEFUL,ASYOULLDISCOVERLATERONINTHISSECTIONTHEXANDTHEYCOORDINATESOFTHEEVENT,ASPASSEDINTHROUGHTHEXANDYARGUMENTS,AREPARTICULARLYNICETOKNOWBECAUSEYOUCANUSETHEMTODETERMINEPRECISELYWHERETHEMOUSECLICKTOOKPLACEFOREXAMPLE,HERESASIMPLEMETHODTHATPRINTSOUTINFORMATIONABOUTAMOUSEDOWNWHENITOCCURSPUBLICBOOLEANMOUSEDOWNEVENTEVT,INTX,INTYSYSTEMOUTPRINTLN“MOUSEDOWNAT“X“,”YRETURNTRUEBYINCLUDINGTHISMETHODINYOURAPPLET,EVERYTIMEYOURUSERCLICKSTHEMOUSEINSIDEYOURAPPLET,THISMESSAGEWILLGETPRINTEDNOTETHATTHISMETHOD,UNLIKETHEOTHERSYSTEMMETHODSYOUVESTUDIEDTHISFAR,RETURNSABOOLEANVALUEINSTEADOFNOTRETURNINGANYTHINGVOIDTHISWILLBECOMEIMPORTANTTOMORROWWHENYOUCREATEUSERINTERFACESANDTHENMANAGEINPUTTOTHESEINTERFACESHAVINGANEVENTHANDLERRETURNTRUEORFALSEDETERMINESWHETHERAGIVENUICOMPONENTCANINTERCEPTANEVENTORWHETHERITNEEDSTOPASSITONTOTHEENCLOSINGCOMPONENTTHEGENERALRULEISTHATIFYOURMETHODDEALSWITHTHEEVENT,ITSHOULDRETURNTRUE,WHICHFORTHEFOCUSOFTODAYSLESSONISALMOSTALWAYSTHECASETHESECONDHALFOFTHEMOUSECLICKISTHEMOUSEUPMETHOD,WHICHISCALLEDWHENTHEMOUSEBUTTONISRELEASEDTOHANDLEAMOUSEUPEVENT,ADDTHEMOUSEUPMETHODTOYOURAPPLETMOUSEUPLOOKSJUSTLIKEMOUSEDOWNPUBLICBOOLEANMOUSEUPEVENTEVT,INTX,INTYANEXAMPLESPOTSINTHISSECTION,YOULLCREATEANEXAMPLEOFANAPPLETTHATUSESMOUSEEVENTSMOUSEDOWNEVENTSINPARTICULARTHESPOTSAPPLETSTARTSWITHABLANKSCREENANDTHENSITSANDWAITSWHENYOUCLICKTHEMOUSEONTHATSCREEN,ABLUEDOTISDRAWNYOUCANPLACEUPTOTENDOTSONTHESCREENFIGURE121SHOWSTHESPOTSAPPLETLETSSTARTFROMTHEBEGINNINGANDBUILDTHISAPPLET,STARTINGFROMTHEINITIALCLASSDEFINITIONIMPORTJAVAAWTGRAPHICSIMPORTJAVAAWTCOLORIMPORTJAVAAWTEVENTPUBLICCLASSSPOTSEXTENDSJAVAAPPLETAPPLETFINALINTMAXSPOTS10INTXSPOTSNEWINTMAXSPOTSINTYSPOTSNEWINTMAXSPOTSINTCURRSPOTS0THISCLASSUSESTHREEOTHERAWTCLASSESGRAPHICS,COLOR,ANDEVENTTHATLASTCLASS,EVENT,NEEDSTOBEIMPORTEDINANYAPPLETSTHATUSEEVENTSTHECLASSHASFOURINSTANCEVARIABLESACONSTANTTODETERMINETHEMAXIMUMNUMBEROFSPOTSTHATCANBEDRAWN,TWOARRAYSTOSTORETHEXANDYCOORDINATESOFTHESPOTSTHATHAVEALREADYBEENDRAWN,ANDANINTEGERTOKEEPTRACKOFTHENUMBEROFTHECURRENTSPOTNOTETHISCLASSDOESNTINCLUDETHEIMPLEMENTSRUNNABLEWORDSINITSDEFINITIONASYOULLSEELATERONASYOUBUILDTHISAPPLET,ITALSODOESNTHAVEARUNMETHODWHYNOTBECAUSEITDOESNTACTUALLYDOANYTHINGONITSOWNALLITDOESISWAITFORINPUTANDTHENDOSTUFFWHENINPUTHAPPENSTHERESNONEEDFORTHREADSIFYOURAPPLETISNTACTIVELYDOINGSOMETHINGALLTHETIMELETSSTARTWITHTHEINITMETHOD,WHICHHASONELINE,TOSETTHEBACKGROUNDTOWHITEPUBLICVOIDINITSETBACKGROUNDCOLORWHITESETTHEBACKGROUNDHERE,INSTEADOFINPAINT,BECAUSEPAINTISCALLEDREPEATEDLYEACHTIMEANEWSPOTISADDEDBECAUSEYOUREALLYNEEDTOSETTHEBACKGROUNDONLYONCE,PUTTINGITINTHEPAINTMETHODUNNECESSARILYSLOWSDOWNTHATMETHODPUTTINGITHEREISAMUCHBETTERIDEATHEMAINACTIONOFTHISAPPLETOCCURSONTHEMOUSEDOWNMETHOD,SOLETSADDTHATONENOWPUBLICBOOLEANMOUSEDOWNEVENTEVT,INTX,INTYIFCURRSPOTSMAXSPOTSADDSPOTX,YELSESYSTEMOUTPRINTLN“TOOMANYSPOTS”RETURNTRUEWHENTHEMOUSECLICKOCCURS,THEMOUSEDOWNMETHODTESTSTOSEEWHETHERTHEREARELESSTHANTENSPOTSIFSO,ITCALLSTHEADDSPOTMETHODWHICHYOULLWRITESOONIFNOT,ITJUSTPRINTSANERRORMESSAGEFINALLY,ITRETURNSTRUE,BECAUSEALLTHEEVENTMETHODSHAVETORETURNABOOLEANVALUEUSUALLYTRUEWHATDOESADDSPOTDOITADDSTHECOORDINATESOFTHESPOTTOTHEARRAYSTHATSTORETHECOORDINATES,INCREMENTSTHECURRSPOTSVARIABLE,ANDTHENCALLSREPAINTVOIDADDSPOTINTX,INTYXSPOTSCURRSPOTSXYSPOTSCURRSPOTSYCURRSPOTSREPAINT（）YOUMAYBEWONDERINGWHYYOUHAVETOKEEPTRACKOFALLTHEPASTSPOTSINADDITIONTOTHECURRENTSPOTTHEREASONISBECAUSEOFREPAINTEACHTIMEYOUPAINTTHESCREEN,YOUHAVETOPAINTALLTHEOLDSPOTSINADDITIONTOTHENEWESTSPOTOTHERWISE,EACHTIMEYOUPAINTEDANEWSPOT,THEOLDERSPOTSWOULDGETERASEDNOW,ONTOTHEPAINTMETHODPUBLICVOIDPAINTGRAPHICSGGSETCOLORCOLORBLUEFORINTI0ICURRSPOTSIGFILLOVALXSPOTSI10,YSPOTSI10,20,20INSIDEPAINT,YOUJUSTLOOPTHROUGHTHESPOTSYOUVESTOREDINTHEXSPOTSANDYSPOTSARRAYS,PAINTINGEACHONEACTUALLY,PAINTINGTHEMALITTLETOTHERIGHTANDUPWARDSOTHATTHESPOTISPAINTEDAROUNDTHEMOUSEPOINTERRATHERTHANBELOWANDTOTHERIGHTTHATSITTHATSALLYOUNEEDTOCREATEANAPPLETTHATHANDLESMOUSECLICKSEVERYTHINGELSEISHANDLEDFORYOUYOUHAVETOADDTHEAPPROPRIATEBEHAVIORTOMOUSEDOWNORMOUSEUPTOINTERCEPTANDHANDLETHATEVENTLISTING121SHOWSTHEFULLTEXTFORTHESPOTSAPPLETTYPELISTING121THESPOTSAPPLET1IMPORTJAVAAWTGRAPHICS2IMPORTJAVAAWTCOLOR3IMPORTJAVAAWTEVENT45PUBLICCLASSSPOTSEXTENDSJAVAAPPLETAPPLET67FINALINTMAXSPOTS108INTXSPOTSNEWINTMAXSPOTS9INTYSPOTSNEWINTMAXSPOTS10INTCURRSPOTS01112PUBLICVOIDINIT13SETBACKGROUNDCOLORWHITE141516PUBLICBOOLEANMOUSEDOWNEVENTEVT,INTX,INTY17IFCURRSPOTSMAXSPOTS18ADDSPOTX,Y19ELSESYSTEMOUTPRINTLN“TOOMANYSPOTS”20RETURNTRUE212223VOIDADDSPOTINTX,INTY24XSPOTSCURRSPOTSX25YSPOTSCURRSPOTSY26CURRSPOTS27REPAINT282930PUBLICVOIDPAINTGRAPHICSG31GSETCOLORCOLORBLUE32FORINTI0ICURRSPOTSI33GFILLOVALXSPOTSI10,YSPOTSI10,20,20343536MOUSEMOVEMENTSEVERYTIMETHEMOUSEISMOVEDASINGLEPIXELINANYDIRECTION,AMOUSEMOVEEVENTISGENERATEDTHEREARETWOMOUSEMOVEMENTEVENTSMOUSEDRAGS,WHERETHEMOVEMENTOCCURSWITHTHEMOUSEBUTTONPRESSEDDOWN,ANDPLAINMOUSEMOVEMENTS,WHERETHEMOUSEBUTTONISNTPRESSEDTOMANAGEMOUSEMOVEMENTEVENTS,USETHEMOUSEDRAGANDMOUSEMOVEMETHODSMOUSEDRAGANDMOUSEMOVETHEMOUSEDRAGANDMOUSEMOVEMETHODS,WHENINCLUDEDINYOURAPPLETCODE,INTERCEPTANDHANDLEMOUSEMOVEMENTEVENTSTHEMOUSEMOVEMETHOD,FORPLAINMOUSEPOINTERMOVEMENTSWITHOUTTHEMOUSEBUTTONPRESSED,LOOKSMUCHLIKETHEMOUSECLICKMETHODSPUBLICBOOLEANMOUSEMOVEEVENTEVT,INTX,INTYTHEMOUSEDRAGMETHODHANDLESMOUSEMOVEMENTSMADEWITHTHEMOUSEBUTTONPRESSEDDOWNACOMPLETEDRAGGINGMOVEMENTCONSISTSOFAMOUSEDOWNEVENT,ASERIESOFMOUSEDRAGEVENTSFOREACHPIXELTHEMOUSEISMOVED,ANDAMOUSEUPEVENWHENTHEBUTTONISRELEASEDTHEMOUSEDRAGMETHODLOOKSLIKETHISPUBLICBOOLEANMOUSEDRAGEVENTEVT,INTX,INTYMOUSEENTERANDMOUSEEXITFINALLY,THEREARETHEMOUSEENTERANDMOUSEEXITMETHODSTHESETWOMETHODSARECALLEDWHENTHEMOUSEPOINTERENTERSTHEAPPLETORWHENITEXITSTHEAPPLETINCASEYOUREWONDERINGWHYYOUMIGHTNEEDTOKNOWTHIS,ITSMOREUSEFULONCOMPONENTSOFUSERINTERFACESTHATYOUMIGHTPUTINSIDEANAPPLETYOULLLEARNMOREABOUTUITOMORROWBOTHMOUSEENTERANDMOUSEEXITHAVESIMILARSIGNATURESTHREEARGUMENTSTHEEVENTOBJECTANDTHEXANDYCOORDINATESOFTHEPOINTWHERETHEMOUSEENTEREDOREXITEDTHEAPPLETPUBLICBOOLEANMOUSEENTEREVENTEVT,INTX,INTYPUBLICBOOLEANMOUSEEXITEVENTEVT,INTX,INTYANEXAMPLEDRAWINGLINESEXAMPLESALWAYSHELPTOMAKECONCEPTSMORECONCRETEINTHISSECTIONYOULLCREATEANAPPLETTHATENABLESYOUTODRAWSTRAIGHTLINESONTHESCREENBYDRAGGINGFROMTHESTARTPOINTTOTHEENDPOINTFIGURE122SHOWSTHEAPPLETATWORKASWITHTHESPOTSAPPLETONWHICHTHISAPPLETISBASED,LETSSTARTWITHTHEBASICDEFINITIONANDWORKOURWAYTHROUGHITLISTING122SHOWSTHETOPOFTHELINESAPPLETTYPELISTING122THETOPOFTHELINESAPPLET1IMPORTJAVAAWTGRAPHICS2IMPORTJAVAAWTCOLOR3IMPORTJAVAAWTEVENT4IMPORTJAVAAWTPOINT56PUBLICCLASSLINESEXTENDSJAVAAPPLETAPPLET78FINALINTMAXLINES109POINTSTARTSNEWPOINTMAXLINES/STARTINGPOINTS10POINTENDSNEWPOINT10/ENDINGPOINTS11POINTANCHOR/STARTOFCURRENTLINE12POINTCURRENTPOINT/CURRENTENDOFLINE13INTCURRLINE0/NUMBEROFLINES1415PUBLICVOIDINIT16SETBACKGROUNDCOLORWHITE1718COMPAREDTOSPOTS,THISAPPLETADDEDAFEWEXTRATHINGSUNLIKESPOTS,WHICHKEEPSTRACKOFINDIVIDUALINTEGERCOORDINATES,THISONEKEEPSTRACKOFPOINTOBJECTSPOINTSREPRESENTANXANDAYCOORDINATE,ENCAPSULATEDINASINGLEOBJECTTODEALWITHPOINTS,YOUIMPORTTHEPOINTCLASSLINE4ANDSETUPABUNCHOFINSTANCEVARIABLESTHATHOLDPOINTSTHESTARTSARRAYHOLDSPOINTSREPRESENTINGTHESTARTSOFLINESALREADYDRAWNTHEENDSARRAYHOLDSTHEENDPOINTSOFTHOSESAMELINESANCHORHOLDSTHESTARTINGPOINTOFTHELINECURRENTLYBEINGDRAWNCURRENTPOINTHOLDSTHECURRENTENDPOINTOFTHELINECURRENTLYBEINGDRAWNCURRLINEHOLDSTHECURRENTNUMBEROFLINESTOMAKESUREYOUDONTGOOVERMAXLINESFINALLY,THEINITMETHODLINES15THROUGH17,ASINTHESPOTSAPPLET,SETSTHEBACKGROUNDOFTHEAPPLETTOWHITETHETHREEMAINEVENTSTHISAPPLETDEALSWITHAREMOUSEDOWN,TOSETTHEANCHORPOINTFORTHECURRENTLINE,MOUSEDRAG,TOANIMATETHECURRENTLINEASITSBEINGDRAWN,ANDMOUSEUP,TOSETTHEENDINGPOINTFORTHENEWLINEGIVENTHATYOUHAVEINSTANCEVARIABLESTOHOLDEACHOFTHESEVALUES,ITSMERELYAMATTEROFPLUGGINGTHERIGHTVARIABLESINTOTHERIGHTMETHODSHERESMOUSEDOWN,WHICHSETSTHEANCHORPOINTWHILETHEMOUSEISBEINGDRAGGEDTODRAWTHELINE,THEAPPLETANIMATESTHELINEBEINGDRAWNASYOUDRAWTHEMOUSEAROUND,THENEWLINEMOVESWITHITFROMTHEANCHORPOINTTOTHETIPOFTHEMOUSETHEMOUSEDRAGEVENTCONTAINSTHECURRENTPOINTEACHTIMETHEMOUSEMOVES,SOUSETHATMETHODTOKEEPTRACKOFTHECURRENTPOINTANDTOREPAINTFOREACHMOVEMENTSOTHELINE“ANIMATES”THENEWLINEDOESNTGETADDEDTOTHEARRAYSOFOLDLINESUNTILTHEMOUSEBUTTONISRELEASEDHERESMOUSEUP,WHICHTESTSTOMAKESUREYOUHAVENTEXCEEDEDTHEMAXIMUMNUMBEROFLINESBEFORECALLINGTHEADDLINEMETHODDESCRIBEDNEXTPUBLICBOOLEANMOUSEUPEVENTEVT,INTX,INTYIFCURRLINEMAXLINESADDLINEX,YELSESYSTEMOUTPRINTLN“TOOMANYLINES”RETURNTRUETHEADDLINEMETHODISWHERETHEARRAYSOFLINESGETUPDATEDANDWHERETHEAPPLETISREPAINTEDTOTAKETHENEWLINEINTOEFFECTVOIDADDLINEINTX,INTYSTARTSCURRLINEANCHORENDSCURRLINENEWPOINTX,YCURRLINECURRENTPOINTNULLREPAINTNOTETHATINTHISLINEYOUALSOSETCURRENTPOINTTONULLWHYBECAUSETHECURRENTLINEINPROCESSISOVERBYSETTINGCURRENTPOINTTONULL,YOUCANTESTFORTHATVALUEINTHEPAINTMETHODPAINTINGTHEAPPLETMEANSDRAWINGALLTHEOLDLINESSTOREDINTHESTARTSANDENDSARRAYS,ASWELLASDRAWINGTHECURRENTLINEINPROCESSWHOSEENDPOINTSAREINANCHORANDCURRENTPOINT,RESPECTIVELYTOSHOWTHEANIMATIONOFTHECURRENTLINE,DRAWITINBLUEHERESTHEPAINTMETHODFORTHELINESAPPLETPUBLICVOIDPAINTGRAPHICSG/DRAWEXISTINGLINESFORINTI0ICURRLINEIGDRAWLINESTARTSIX,STARTSIY,ENDSIX,ENDSIY/DRAWCURRENTLINEGSETCOLORCOLORBLUEIFCURRENTPOINTNULLGDRAWLINEANCHORX,ANCHORY,CURRENTPOINTX,CURRENTPOINTYINPAINT,WHENYOUREDRAWINGTHECURRENTLINE,YOUTESTFIRSTTOSEEWHETHERCURRENTPOINTISNULLIFITIS,THEAPPLETISNTINTHEMIDDLEOFDRAWINGALINE,SOTHERESNOREASONTOTRYDRAWINGALINETHATDOESNTEXISTBYTESTINGFORCURRENTPOINTANDBYSETTINGCURRENTPOINTTONULLINTHEADDLINEMETHOD,YOUCANPAINTONLYWHATYOUNEEDTHATSITJUST60LINESOFCODEANDAFEWBASICMETHODS,ANDYOUHAVEAVERYBASICDRAWINGAPPLICATIONINYOURWEBBROWSERLISTING123SHOWSTHEFULLTEXTOFTHELINESAPPLETSOTHATYOUCANPUTTHEPIECESTOGETHERTYPELISTING123THELINESAPPLET1IMPORTJAVAAWTGRAPHICS2IMPORTJAVAAWTCOLOR3IMPORTJAVAAWTEVENT4IMPORTJAVAAWTPOINT56PUBLICCLASSLINESEXTENDSJAVAAPPLETAPPLET78FINALINTMAXLINES9POINTSTARTSNEWPOINTMAXLINES/STARTINGPOINTS10POINTENDSNEWPOINT10/ENDINGPOINTS11POINTANCHOR/STARTOFCURRENTLINE12POINTCURRENTPOINT/CURRENTENDOFLINE13INTCURRLINE0/NUMBEROFLINES1415PUBLICVOIDINIT16SETBACKGROUNDCOLORWHITE171819PUBLICBOOLEANMOUSEDOWNEVENTEVT,INTX,INTY20ANCHORNEWPOINTX,Y21RETURNTRUE222324PUBLICBOOLEANMOUSEUPEVENTEVT,INTX,INTY25IFCURRLINEMAXSPOTS26ADDLINEX,Y27ELSESYSTEMOUTPRINTLN“TOOMANYLINES”28RETURNTRUE293031PUBLICBOOLEANMOUSEDRAGEVENTEVT,INTX,INTY32CURRENTPOINTNEWPOINTX,Y33REPAINT34RETURNTRUE353637VOIDADDLINEINTX,INTY38STARTSCURRLINEANCHOR39ENDSCURRLINENEWPOINTX,Y40CURRLINE41CURRENTPOINTNULL42REPAINT434445PUBLICVOIDPAINTGRAPHICSG4647/DRAWEXISTINGLINES48FORINTI0ICURRLINEI49GDRAWLINESTARTSIX,STARTSIY,50ENDSIX,ENDSIY515253/DRAWCURRENTLINE54GSETCOLORCOLORBLUE55IFCURRENTPOINTNULL56GDRAWLINEANCHORX,ANCHORY,57CURRENTPOINTX,CURRENTPOINTY5859KEYBOARDEVENTSKEYBOARDWVWNTSAREGENERATEDWHENEVERUSERSPRESSAKEYONTHEKEYBOARDBYUSINGKEYEVENTS,YOUCANGETHOLDOFTHEVALUESOFTHEKEYSTHEYPRESSEDTOPERFORMANACTIONORMERELYTOGETCHARACTERINPUTFROMTHEUSERSOFYOURAPPLETTHEKEYDOWNMETHODTOCAPTUREAKEYBOARDEVENT,USETHEKEYDOWNMETHODPUBLICBOOLEANKEYDOWNEVENTEVT,INTKEYTHEKEYSGENERATEDBYKEYDOWNEVENTSANDPASSEDINTOKEYDOWNASTHEKEYARGUMENTAREINTEGERSREPRESENTINGASCIICHARACTERVALUES,WHICHINCLUDEALPHANUMERICCHARACTERS,FUNCTIONKEYS,TABS,RETURNS,ANDSOONTOUSETHEMASCHARACTERSFOREXAMPLE,TOPRINTTHEM,YOUNEEDTOCASTTHEMTOCHARACTERSCURRENTCHARCHARKEYHERESASIMPLEEXAMPLEOFAKEYDOWNMETHODTHATDOESNOTHINGBUTPRINTTHEKEYYOUJUSTTYPEDINBOTHITSASCIIANDCHARACTERREPRESENTATIONPUBLICBOOLEANKEYDOWNEVENTEVT,INTKEYSYSTEMOUTPRINTLN“ASCIIVALUE”KEYSYSTEMOUTPRINTLN“CHARACTER”CHARKEYRETURNTRUEDEFAULTKEYSTHEEVENTCLASSPROVIDESASETOFCLASSVARIABLESTHATREFERTOSEVERALSTANDARDNONALPHANUMERICKEYS,SUCHASTHEARROWKEYSIFYOURINTERFACEUSERTHESEKEYS,YOUCANPROVIDEMOREREADABLECODEBYTESTINGFORTHESENAMESINYOURKEYDOWNMETHODRATHERTHANTESTINGFORTHEIRNUMERICVALUESFOREXAMPLE,TOTESTWHETHERTHEUPARROWWASPRESSED,YOUMIGHTUSETHEFOLLOWINGSNIPPETOFCODEIFKEYEVENTUPBECAUSETHEVALUESTHESECLASSVARIABLESHOLDAREINTEGERS,YOUALSOCANUSETHESWITCHSTATEMENTTOTESTFORTHEMTABLE121SHOWSTHESTANDARDEVENTCLASSVARIABLESFORVARIOUSKEYSANDTHEACTURLKEYSTHEYREPRE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