Model&/&View&COMP&401&Spring&2013&Lecture&22&4/9/2013&ColorChooser&Widget&Review&• lec21.v7&• Color&object&embedded&within&the&widget&– Fine&for&a&small&piece&of&immutable&informaJon&– Not&so&great&for&a&complex&abstracJon&• UI&may¬&always&be&needed&Model&–&View&PaQern&• Keep&object&represenJng&the&data&separate&from&widget&providing&the&UI&– Model:&Object&represenJng&abstracJon&within&your&applicaJon.&– View:&Object&(widget)&represenJng&UI&to&model.&COMP&401&::&Spring&2012& 3&Model& View&Inform&when&data&changes.&Inform&when&user&interacts.&ModelVView&Example&• Playlist&– This&is&the&model&object&– Manages&a&list&of&Song&objects&• PlaylistView&– This&is&the&view&object&– Provides&a&UI&for&interacJng&with&Playlist&lec22.v1&• Playlist&lec22.v2&• PlaylistView&– Encapsulates&a&reference&to&Playlist&object&– Builds&a&simple&view&of&the&playlist&lec22.v3&• AddSongWidget&– An&interface&for&adding&a&new&song&to&the&Playlist&lec22.v4&• ConnecJng&model&to&view&– Model&needs&to&inform&the&view&whenever&it&changes&so&that&the&view&can&rebuild&to&reflect&any&changes.&• My&approach&here&is&to&make&the&model&observable.&– And&to®ister&PlaylistView&as&an&observer&• Notes:&– revalidate()&required&whenever&contents&of&a&Java&Swing&container&are&changed&lec22.v5&• NoJce&duplicaJon&of&code&in&constructor&when&list&is&first&built&and&when&rebuilt&when&responding&to&model&update.&– Refactor&into&a&helper&method.&• JScrollPane&– Wraps&another&Swing&component&that&may&change&size&and&provides&scrolling&view&as&needed.&lec22.v6&• Add&a&shuffle&buQon&lec22.v7&• Create&more&interesJng&song&lisJng&– SongLisJngWidget&• Includes&a&buQons&for&removing&the&song&from&the&playlist&and&moving&them&up&and&down&the&list.&• BorderFactory&– Swing&class&for&creaJng&borders&for&components&• Unicode&characters&– Lots&of&glyphs&available&– Changed&Song&to&use&star&glyph&for&raJng&• Added&method&to&playlist&for&moving&songs&Model&/&View&Model& View&Inform&when&data&changes.&Inform&when&user&interacts.&Playlist&/&PlaylistView&Playlist&PlaylistView&update()&shuffle()&AddSongWidget&addSong()&SongLisJngWidget&SongLisJngWidget&SongLisJngWidget&SongLisJngWidget&SongLisJngWidget&SongLisJngWidget&removeSong(),&moveSong()&Model&/&View&Summary&• Model&provides&access&to&an&abstracJon.&– Any&manipulaJon&/&modificaJon&done&via&public&methods&provided&by&model.&• View&builds&an&interface&for&rendering¤t&state&of&the&model.&– InteracJons&with&interface&translated&to&appropriate&calls&on&model&methods.&ModelVView&Inadequacies&• Good&for&simple,&direct&UI&elements&– Model&driving&UI&is&just&one&object&– UI&reflects&model&state&directly&– User&interacJons&with&view&have&direct&mapping&to&updates&to&model.&• Complex&behavior&harder&to&express&– Dynamic&user&interfaces&– Complex&models&– Contextual&user&interacJons&COMP&401&::&Spring&2012& 15&Classic&MVC&COMP&401&::&Spring&2012& 16&hQp://www.oracle.com/technetwork/arJcles/javase/mvcV136693.html&Alternate&MVC&COMP&401&::&Spring&2012& 17&hQp://www.oracle.com/technetwork/arJcles/javase/mvcV136693.html&A7&• ChessGame,&ChessPiece&make&up&the&model&• ChessGameView&is&view&•
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