Uppsala University. Assignment 3. Separation into Model-View TableModel ListModel ( multiple inheritance or adapter) Renderer (delegation)

Transcription

1 ToDo-list Assignment 3 Separation into Model-View TableModel ListModel ( multiple inheritance or adapter) Renderer (delegation) A new component Extend Swing with your own design Theme Modify look&feel 2/12/10 #1

2 OWN COMPONENT 2/12/10 #2

3 Component Size: respect the size given by the layout manager. In some cases you might want to provide more information to the LayoutManager override getminimumsize, getpreferredsize, getmaximumsize Reuse: no hardcoded strings/colors/fonts/ icons in code Make sure the component is possible to reuse by someone else, just like a standard Jlabel, etc. 2/12/10 #3

4 JComponent public class Square extends JComponent { private Rectangle2D.Double square = new Rectangle2D.Double(20,20,150,150); // no sizes like this! private String text; public void setvalue(string s) { text = s; repaint(); public void paintcomponent(graphics g) { Graphics2D g2d = (Graphics2D)g.create(); g2d.setpaint(color.red); // no colors like this! g2d.fill(square); g2d.setpaint(color.black); // no colors like this! g2d.drawstring(text, 25, 100); // position should be calculated! g2d.dispose(); //clean up 2/12/10 #4

5 JComponent Square sq = new Square(); sq.setvalue( Java2D ); 2/12/10 #5

6 JComponent public class JMyComponent extends JComponent { private XX xx; // private state public void setvalueofxx(xx xx){ // calculate new state this.xx = xx; // repaint new state if needed if (needed) repaint(); public void paintcomponent(graphics g) { // make copy of graphics so we may set attributes Graphics2D g2d = (Graphics2D)g.create(); // paint and stuff // goes here g2d.dispose(); //clean up 2/12/10 #6

7 MODEL-VIEW 2/12/10 #7

8 Model View Control MVC comes from Smalltalk Invented ~1980 by Trygve Reenskaug MVC extremely important for GUIs MVC contains a number of design patterns Protocols instead of components (= interface) Weak coupling (=Observer) Separation of Model and View 2/12/10 #8

9 Model MVC Contains the data we want to display Data may not exist; can be created at runtime (by calculating or from SQL etc.) View The visual representation Control Manages the glue between Model and View, how to modify the data 2/12/10 #9

10 Model-View In Java: JList / ListModel, JTable / TableModel Don t mix presentation and logic Your job is to care about the model, the view is done automatically The model notifies the View when something has changed 2/12/10 #10

11 Two Views can share one Model Model - View ListModel m = p.add(new JList(m)); p.add(new JList(m)); 2/12/10 #11

12 Sample App-controller public class AppController { //singleton class details private static AppController instance = null; protected AppController() {... public static AppController getinstance() {... //controller details // Accessible Component: textcomponent private JTextComponent textcomponent = null; public void settextcomponent(textcomponent tc) {... public void handleescapeaction() {... public void handleexitaction() {... 2/12/10 #12

13 MV better than MVC? In true MVC, C should not have to know much about V All three should be as independent as possible In reality, it is difficult to implement C without telling something about V or M Java uses M + V(C) Useful article: 2/12/10 #13

14 Changes in Model If Model changes, View should automatically repaint but how? These notification methods are often called fire Lightweight notification Information is sent that some change happend If View wants to know more, it should ask Model Stateful notification Information about what changed is sent Must create a class (=Event) for each change-type Optimal design in OOP 2/12/10 #14

15 Javadoc for JList JList() Constructs a JList with an empty, readonly, model. JList(ListModel datamodel) Constructs a JList that displays elements from the specified, non-null, model. JList(Object[] listdata) Constructs a JList that displays the elements in the specified array. JList(Vector<?> listdata) Constructs a JList that displays the elements in the specified Vector. 2/12/10 #15

16 Simple Model-View for lists // we need to implement 2 methods in AbstractListModel: // Object getelementat(int index) // int getsize() ListModel bigdata = new AbstractListModel() { ; public int getsize() { return 1000*1000; public Object getelementat(int index) { return "Index " + index; panel.add(new JScrollPane(new JList(bigData)); 2/12/10 #16

17 Full example public class ListModelUI extends JFrame { ListModelUI() { super("listmodelui"); ListModel bigdata = new AbstractListModel() { public int getsize() { return 1000*1000; public Object getelementat(int index) { return "Index " + index; ; add(new JScrollPane(new JList(bigData))); pack(); setvisible(true); public static void main(string args[]) { new ListModelUI(); 2/12/10 #17

18 Model that contains random data public class RandomModelUI extends JFrame { RandomModelUI() { super("randommodelui"); ListModel rnddata = new AbstractListModel() { private Random rnd = new Random(); public int getsize() { return 1000*1000; public Object getelementat(int index) { return Index " + index + " = " + rnd.nextint(100); ; add(new JScrollPane(new JList(rndData))); pack(); setvisible(true); public static void main(string args[]) { new RandomModelUI(); 2/12/10 #18

19 Large data public class ModelView1 extends JFrame { public ModelView1() { setlayout(new BorderLayout()); add(new JScrollPane(new JTable(new LargeNumberModel())), BorderLayout.CENTER); /** Table model that calculates the square of the row number. */ private class LargeNumberModel extends AbstractTableModel { /** Headers. */ public String getcolumnname(int col) { if (col == 0) return "X"; else return "X^2"; /** rows... */ public int getrowcount() { return 1000*1000; /** Two columns. */ public int getcolumncount() { return 2; /** Row number for the first column and the square for the second. */ public Object getvalueat(int row, int col) { if (col == 0) return row; else return (long) row * (long) row; 2/12/10 #19

20 Large data (screenshots) 2/12/10 #20

21 Large data (conclusion) The table has rows, but works nicely The model provides data on demand You don t need to store all those objeckts The table does not need to know anything about the data, just how to display it 2/12/10 #21

22 Tips Your TableModel should inherit from AbstractTableModel (not DefaultTableModel) You use the different fire-methods to repaint the table. Use the correct fire method firetabledatachanged() forces a redraw of everything, and this is not correct 2/12/10 #22

23 Fire methods You need those in bold: firetabledatachanged() firetablestructurechanged() firetablerowsinserted(int first, int last) firetablerowsupdated(int first, int last) firetablerowsdeleted(int first, int last) firetablecellupdated(int row, int column) 2/12/10 #23

24 OBSERVER 2/12/10 #24

25 Observer Class Diagram Observable +addobserver(observer) +deleteobserver(observer) +notifyobservers(object) #haschanged() : boolean #setchanged() BankAccount +widthdraw(double) : long +deposit(double) : long +getbalance() : double Observer +update(observable, Object) AccountView +update(observable, Object) SummaryView +update(observable, Object) 2/12/10 #25

26 Observer (=Listener) // see javadoc for javax.swing.event.eventlistenerlist private EventListenerList listenerlist = new EventListenerList(); public void addlistener(listener l) { listenerlist.add(listener.class, l); public void removelistener(listener l) { listenerlist.remove(listener.class, l); protected void notify(event event) { // Guaranteed to return a non-null array Object[] listeners = listenerlist.getlistenerlist(); // Process the listeners last to first, notifying // those that are interested in this event for (int i = listeners.length-2; i>=0; i-=2) { if (listeners[i] == Listener.class) { ((Listener)listeners[i+1]).notify(event); 2/12/10 #26

27 Our own listener Let s say we want to tell our todo-application the user has selected a file We separate the selection from TODO.java But TODO.java wants to be notified when this happens We solve this using a listener 2/12/10 #27

28 Step 1: interfaces // the listener needs to implement this interface SelectionListener { public void selected(selectionevent); // The sender will send this information interface SelectionEvent { File getselection(); // events could be a base class, not an interface 2/12/10 #28

29 Step 2: TODO.java FileSelector fs = new FileSelector(); panel.add(fs); fs.addlistener(new SelectionListener() { public void selected(selectionevent e) { File file = e.getselection(); // do something with file, display it? ; 2/12/10 #29

30 Step 3: FileSelector import java.util.concurrent.copyonwritearraylist; public class FileSelector { // something about how to select files private CopyOnWriteArrayList<SelectionListener> listeners = new CopyOnWriteArrayList<SelectionListener>(); public void addlistener(selectionlistener l) { listeners.add(l); public void removelistener(selectionlistener l) { listeners.remove(l); private void fire(final File file) { SelectionEvent selectionevent= new SelectionEvent() { public File getselection() { return file; ; for (SelectionListener l : listeners) { try { l.selected(selectionevent); catch (Exception e) { e.printstacktrace(); // END FileSelector 2/12/10 #30

31 Renderer JTable does not care about the table content It delegates this to the TableModel JTable does not care about the cell content It delegates this to Renderer A Renderer is like a rubber stamp, that is used to paint each cell of the table The same stamp/renderer should be used for all cells for efficiency! 2/12/10 #31

32 Renderer You can register different Renderers for different Objects setdefaultrenderer(file.class, new CoolFileRenderer()); TableCellRenderer Component gettablecellrenderercomponent (JTable table, Object value, boolean isselected, boolean hasfocus, int row, int column) Returns the component used for drawing the cell 2/12/10 #32