week 9, class 3: model-view-controller today happens-before adapter and façade pattern (high-level)...
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Week 9, Class 3:Model-View-Controller Today
Happens-Before Adapter and Façade Pattern (high-level)
Tuesday: Project code due, 11pm Wednesday: Quiz
Choose a pattern Refactor code to meet a design goal Discuss how code/pattern meets a design goal Adapter and Façade Patterns (high-level) Synchronization
Friday: Review for Final & Class Climate evaluationsSE-2811
Slide design: Dr. Mark L. HornickContent: Dr. Hornick
Errors: Dr. Yoder
1
The rigormeter is at 2 today
https://www.rose-hulman.edu/~bryan/images/rigor.htmlSE-2811Dr.Yoder 2
Ex.
public void a() {
System.out.println(“x”);
System.out.println(“y”);
}
public void b() {
System.out.println(“x”);
System.out.println(“y”);
}
SE-2811Dr.Yoder 3
Prove the following code is(n’t) free of data races:
Ex.
public void a() {
x = 5;
System.out.println(“x”);
}
public void a() {
x = 5;
System.out.println(“x”);
}
SE-2811Dr.Yoder 4
Prove the following code is(n’t) free of data races:
Ex.
public void a() {
synchronized {
x = 5;
System.out.println(“x”);
}
}
SE-2811Dr.Yoder 5
Prove the following code is(n’t) free of data races:
Ex.
if(theLogger==null){
synchronized (EventLogger.class){
if(theLogger == null){
theLogger = new EventLogger(path);
}
}
}
SE-2811Dr.Yoder 6
Write whether this code contains any data races. Explain your answer. Assume loggers is not volatile.
Ex.
if(theLogger==null){
synchronized (EventLogger.class){
if(theLogger == null){
theLogger = new EventLogger(path);
}
}
}
SE-2811Dr.Yoder 7
Write whether this code contains any data races. Explain your answer. Assume loggers is volatile.
Ex.
if(loggers.get(path)==null){
synchronized (loggers){
if(loggers.get(path) == null){
Logger logger = new EventLogger(path);
loggers.put(path, logger);
}
}
}SE-2811Dr.Yoder 8
Write whether this code contains any data races. Explain your answer. Assume loggers is not thread safe.
Ex.
if(loggers.get(path)==null){
synchronized (loggers){
if(loggers.get(path) == null){
Logger logger = new EventLogger(path);
loggers.put(path, logger);
}
}
}SE-2811Dr.Yoder 9
Write whether this code contains any data races. Explain your answer. Assume loggers is thread safe.
SE-2811Slide design: Dr. Mark L. Hornick
Most Content: Dr. HornickSome Content and Most Errors: Dr. Yoder
The Façade Pattern
SE-2811Dr. Mark L. Hornick 10
Watching a Movie...
Use multiple interfaces (remotes) to Turn on Receiver/amplifier Turn on TV/Monitor Turn on DVD player Set the Receiver input to DVD Put the Monitor in HDMI input mode Set the Receiver volume to medium Set Receiver to DTS Surround Start the DVD player.
Interacting with the following classes:• Receiver/Amplifier• TV/Monitor• DVD• Camera with blue
screen
To decrease the complexity..
We can create a new class TheaterFacade (e.g. a universal remote) which exposes a few methods such as watchMovie().
The façade treats the various components as a sub system and calls on them to implement the watchMovie method.
So to watch a movie, we just call one method, watchMovie and it communicates with the Monitor, DVD, and Receiver for us.
The façade still leaves the subsystem accessible to be used directly. If you need the advanced functionality of the subsystem classes, they are available for use.
The Problem
Complex system Consisting of multiple
subsystems Each with its own interface,
each with many methods
Difficult for clients (blue) to deal with
Facade Solution
Solution Centralize subsystem
interface Simplify/reduce number of
centralized methods Façade presents new
unified “face” to clients Facade
Removing the burden from beginning Java developers with a Façade (WinPlotter)
SE-2811Dr. Mark L. Hornick 15
class winPlotter
DrawingWindow
- currentPenColor: java.awt.Color- items: java.util.ArrayList- contentPane: java.awt.Container- showGrid: boolean- backgroundColor: java.awt.Color- xinc: int- yinc: int- gridColor: java.awt.Color- drawPanel: DrawPanel
+ DrawingWindow()+ setWindowSize(x :int, y :int) : void+ erase() : void+ setWindowTitle(title :String) : void+ setPenColor(c :Color) : void+ setBackgroundColor(backgroundColor :Color) : void+ drawLineTo(x :int, y :int) : void+ moveTo(x :int, y :int) : void+ drawPointAt(x :int, y :int) : void+ textAt(x :int, y :int, text :String) : void+ setGrid(showGrid :boolean, xinc :int, yinc :int, gridColor :Color) : void+ paint(gr :Graphics) : void
DrawPanel
# paintComponent(g :Graphics) : void+ doPaint(gr :Graphics) : void
DrawItem
+ MOVE: int = 0 {readOnly}+ DRAW: int = 1 {readOnly}+ POINT: int = 2 {readOnly}+ TEXT: int = 3 {readOnly}+ opCode: int+ x: int = 0+ y: int = 0+ text: String+ color: Color
+ DrawItem(x :int, y :int, opCode :int, color :Color)+ DrawItem(x :int, y :int, opCode :int, color :Color, text :String)
FrameWindowConstants
AccessibleRootPaneContainer
TransferHandler.HasGetTransferHandler
swing::JFrame
+ EXIT_ON_CLOSE: int = 3 {readOnly}- defaultLookAndFeelDecoratedKey: Object = new StringBuffe... {readOnly}- defaultCloseOperation: int = HIDE_ON_CLOSE- transferHandler: TransferHandler# rootPane: JRootPane# rootPaneCheckingEnabled: boolean = false# accessibleContext: AccessibleContext = null
+ JFrame()+ JFrame(gc :GraphicsConfiguration)+ JFrame(title :String)+ JFrame(title :String, gc :GraphicsConfiguration)# frameInit() : void# createRootPane() : JRootPane# processWindowEvent(e :WindowEvent) : void+ setDefaultCloseOperation(operation :int) : void+ getDefaultCloseOperation() : int+ setTransferHandler(newHandler :TransferHandler) : void+ getTransferHandler() : TransferHandler+ update(g :Graphics) : void+ setJMenuBar(menubar :JMenuBar) : void+ getJMenuBar() : JMenuBar# isRootPaneCheckingEnabled() : boolean# setRootPaneCheckingEnabled(enabled :boolean) : void# addImpl(comp :Component, constraints :Object, index :int) : void+ remove(comp :Component) : void+ setLayout(manager :LayoutManager) : void+ getRootPane() : JRootPane# setRootPane(root :JRootPane) : void+ setIconImage(image :Image) : void+ getContentPane() : Container+ setContentPane(contentPane :Container) : void+ getLayeredPane() : JLayeredPane+ setLayeredPane(layeredPane :JLayeredPane) : void+ getGlassPane() : Component+ setGlassPane(glassPane :Component) : void+ getGraphics() : Graphics+ repaint(time :long, x :int, y :int, width :int, height :int) : void+ setDefaultLookAndFeelDecorated(defaultLookAndFeelDecorated :boolean) : void+ isDefaultLookAndFeelDecorated() : boolean# paramString() : String+ getAccessibleContext() : AccessibleContext
JComponentAccessible
swing::JPanel
- uiClassID: String = "PanelUI" {readOnly}
+ JPanel(layout :LayoutManager, isDoubleBuffered :boolean)+ JPanel(layout :LayoutManager)+ JPanel(isDoubleBuffered :boolean)+ JPanel()+ updateUI() : void+ getUI() : PanelUI+ setUI(ui :PanelUI) : void+ getUIClassID() : String- writeObject(s :ObjectOutputStream) : void# paramString() : String+ getAccessibleContext() : AccessibleContext
::Lab1App
«facade»WinPlotter
- window: DrawingWindow- width: int- height: int- xmin: int- ymin: int- xmax: int- ymax: int- xscale: float- yscale: float- showGrid: boolean
+ WinPlotter()- logicalToPixel(xlog :int, ylog :int) : Point+ drawTo(x :int, y :int) : void+ erase() : void+ moveTo(x :int, y :int) : void+ drawPoint(x :int, y :int) : void+ printAt(x :int, y :int, text :String) : void+ setBackgroundColor(red :int, green :int, blue :int) : void+ setPenColor(red :int, green :int, blue :int) : void+ setWindowSize(width :int, height :int) : boolean+ setPlotBoundaries(xmin :int, ymin :int, xmax :int, ymax :int) : boolean+ setGrid(showGrid :boolean, xinc :int, yinc :int, gridColor :Color) : boolean+ setWindowTitle(title :String) : void
+items
*
-drawPanel
-window
Generic Pattern
SE-2811Dr. Mark L. Hornick 16
Facade Applications
Interface to existing library Unify or “clean up” complex interface