Java$UI,$pt.$2$COMP$401$Spring$2013$Lecture$21$4/2/2013$Top$Level$Windows$• JDialog$– Dialog$box$topHlevel$windows.$– Several$types$preHdefined$for$ease$of$use.$• File$choosers,$informaOonal,$input$prompt,$etc.$• JFrame$– Normal$topHlevel$windows$for$UI$• JApplet$– We’ll$be$ignoring$this$for$now.$COMP$401$::$Spring$2012$ 2$JOpOonPane$Examples$• JOpOonPane$provide$quick$and$easy$dialog$boxes.$– showConfirmDialog$• Allows$user$to$confirm$a$choice$with$a$Yes/No/Cancel$response.$– showInputDialog$• Prompts$for$text$input.$– showMessageDialog$• Shows$message,$waits$for$user$to$acknowledge.$• All$of$these$are$“modal”.$– Flow$of$execuOon$is$halted$unOl$dialog$is$dealt$with.$– Method$returns$response$directly.$• lec21.v2$COMP$401$::$Spring$2012$ 3$JFrame$• NonHdialog$topHlevel$window.$– May$or$may$not$have$a$window$bar$• LocaOon$of$which$is$operaOng$system$and$lookHandHfeel$specific$– OperaOon$defined$by$what$is$placed$in$it.$– General$pa[ern$• Main$method$of$program$sets$up$UI$in$a$JFrame$• JFrame$made$visible.$• Rest$of$program$now$responds$asynchronously$to$user$interface$events.$• Hello,$world$revisited.$COMP$401$::$Spring$2012$ 4$Containment$Hierarchy$• JPanel$used$as$content$pane$for$topHlevel$window$is$root$of$“containment$hierarchy”.$– All$user$interface$elements$must$be$placed$in$a$container$(i.e.,$JPanel).$– Containers$can$be$nested$within$containers$• Groups$UI$elements$together$and$allows$subHlayout.$COMP$401$::$Spring$2012$ 5$Layout$Managers$• BorderLayout$– 5$areas:$NORTH,$EAST,$WEST,$SOUTH,$CENTER$– N/E/W/S$also$known$as:$• PAGE_START,$LINE_START,$LINE_END,$PAGE_END$• BoxLayout$– Stacked$either$horizontally$or$verOcally$• GridLayout$– Equal$sized,$regular$grid.$– Specify$number$of$rows$and$columns$at$construcOon.$• 0$indicates$“auto”$for$that$dimension$• Others:$Card,$Flow,$GridBag,$Goup,$Spring$– See$h[p://docs.oracle.com/javase/tutorial/uiswing/layout/visual.html$COMP$401$::$Spring$2012$ 6$Swing$Components$• Text$– JLabel,$JTextField,$JTextArea$• Bu[ons$– JBu[on,$JCheckBox,$JRadioBu[on,$JT o ggl eBu[on$• Sliders$– JSlider$• Lots$of$others$$COMP$401$::$Spring$2012$ 7$UI$Events$• UI$elements$respond$to$interacOon$by$generaOng$“events”.$– Listeners$are$registered$to$receive$noOficaOon$when$a$parOcular$event$occurs.$– Different$listener$interfaces$defined$for$different$kinds$of$events.$• Listening$method$receives$event$informaOon$as$a$parameter.$• UI$elements$are$like$Observable$• Listeners$are$like$Observer$$COMP$401$::$Spring$2012$ 8$Bu[on$Example$• lec21.v3$• addAcOonListener(AcOonListener$l)$– Method$common$to$all$types$of$bu[ons.$– Defined$in$AbstractBu[on$• Parent$of$all$bu[on$types.$– AcOonListener$interface:$• void$acOonPerformed(AcOonEvent$e)$• AcOonEvent$encapsulates$all$event$informaOon$– AcOonEvent$• Parent$class$is$AWTEvent$– Common$informaOon$for$all$event$types.$– getSource()$» Returns$reference$to$object$that$generated$the$event.$• Other$informaOon$provided$specific$to$subclass.$COMP$401$::$Spring$2012$ 9$Java$UI’s$so$far$• Create$a$top$level$window.$• Create$a$JPanel$to$be$content$pane.$• Fill$JPanel$with$other$components$– Bu[ons,$sliders,$etc.$– Containers$with$components$arranged$in$them.$• And$so$forth.$• Connect$UI$events$with$“listeners”$– Listeners$take$acOon$as$response.$– AcOon$may$change/update$UI$• Make$top$level$window$visible.$COMP$401$::$Spring$2012$ 10$Swing$Component$Class$Hierarchy$COMP$401$::$Spring$2012$ 11$java.awt.Component$java.awt.Container$javax.swing.JComponent$JPanel$JScrollPane$JSplitPane$JTabbedPane$JToolBar$JComboBox$JLabel$JList$JProgressBar$JSeparator$JSlider$JToolTip$JTree$AbstractBu[on$$JBu[on$$JToggleBu[on$$$JCheckBox$$$JRadioBu[on$$JMenuItem$$$JMenu$Listener$Types$• Supported$at$awt.Component$– ComponentListener$– FocusListener$– KeyListener$– MouseListener$– MouseMoOonListener$– MouseWheelListener$• Supported$at$awt.Container$– ContainerListener$• Supported$at$AbstractBu[on$– AcOonListener$– ChangeListener$– ItemListener$• Supported$by$individual$components$– AcOonListener$:$JComboBox$– ChangeListener$:$JSlider,$JProgressBar$$$COMP$401$::$Spring$2012$ 12$Keyboard$Concepts$• Keyboard$events$go$to$component$that$currently$has$“focus”.$– setFocusable(boolean$status)$– isFocusable()$– requestFocusInWindow()$• Java$provides$a$framework$for$managing$focus$in$more$sophisOcated$ways$if$necessary.$– h[p://docs.oracle.com/javase/tutorial/uiswing/misc/focus.html#api$• KeyListener$interface$– keyTyped(KeyEvent$e)$$– keyPressed(KeyEvent$e)$– keyReleased(KeyEvent$e)$• Typing$of$character$vs.$pressing$of$key$– Basic$sequence$of$events$generated:$key$press,$key$typed,$key$released$• Important$KeyEvent$methods$– char$getKeyChar()$• This$is$only$valid$for$key$typed$events.$– int$getKeyCode()$– isAltDown(),$isControlDown(),$isShilDown(),$isMetaDown()$COMP$401$::$Spring$2012$ 13$Mouse$Concepts$• MouseListener$– mouseClicked(MouseEvent$e)$– mouseEntered(MouseEvent$e)$– mouseExited(MouseEvent$e)$– mousePressed(MouseEvent$e)$– mouseReleased(MouseEvent$e)$• MouseMoOonListener$– mouseDragged(MouseEvent$e)$– mouseMoved(MouseEvent$e)$• MouseEvent$– PosiOon$info$• RelaOve$to$component:$getX(),$getY(),$getPoint()$• Absolute$posiOon:$$getXOnScreen(),$getYOnScreen()$– Click$info:$getClickCount(),$getBu[on()$– Modifiers:$isAltDown(),$isShilDown(),$etc...$COMP$401$::$Spring$2012$ 14$Composing$Widgets$• A$set$of$related$UI$elements$that$act$as$a$unit$within$your$UI.$• Basic$idea:$– Subclass$JPanel$– In$constructor,$create$and$arrange$UI$components.$– Provide$methods$for$a[aching$listeners,$requesOng$current$state$of$UI,$etc.$• Could$be$straight$delegaOon$or$could$be$mediated$by$more$sophisOcated$logic.$COMP$401$::$Spring$2012$ 15$Color$Chooser$Widget$• lec21.v4$– Basic$widget$construcOon$and$set$up$• lec21.v5$–