Algorithm Programming 1 JAVA GUI with SwingBar-Ilan University

תשס"ז 2006-2007

Moshe Fresko

AWT AWT : Abstract Windowing Toolkit. Tools for

developing Platform Independent GUI. AWT rely on native C code to create User Interface

components. Java 1.0 AWT : Very restrictive. Java 1.1 AWT : Event Model, more OO approach Java 2 (JDK 1.2) – Everything replaced by JFC

(Java Foundation Classes). Swing: GUI part of JFC.

Swing Swing is a powerful collection of UI

components. Multiple look and feel support Customizable look and feel Lightweight UI framework Swing components are written in pure Java

(uses AWT components which use native C codes) MVC (Model View Controller) style component

designs

Some Swing libraries javax.swing.* : Includes swing GUI components and

supporting classes. javax.swing.border.* : Classes that defines borders to

decorate GUI components. javax.swing.event.* : Event handling classes, including new

event and listener classes javax.swing.plaf.* : Definitions of UI objects for the Swing

components javax.swing.table.* : Supporting classes for the Table

component javax.swing.text.* : The swing styled text framework javax.swing.tree.* : Supporting classes for the Tree

component

JComponent Most of the Swing components are subclasses of JComponent. JComponent is the root of “COMPOSITE” pattern. JComponent is a “Container” which has .add(Component) method.

java.lang.Object

java.awt.Component

java.awt.Container

javax.swing.JComponent

JButton JPanel JLabel JComboBox

Example Windowimport javax.swing.* ;import java.awt.event.* ;import java.awt.* ;

public class SimpleWindow {public static void main(String s[]) {

JFrame frame = new JFrame("Simple Window") ;JButton button = new JButton("Hello Button") ;JLabel label = new JLabel("A Label") ;frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE) ;frame.getContentPane().add(button,"Center") ;frame.getContentPane().add(label,"South") ;frame.pack() ;frame.setVisible(true) ;

}}

JComponent features JComponent defines some standard features for

Swing components Borders Component-specified min.,max., and preferred sizes Tool tips Slow-motion rendering for Debugging Auto-scrolling Double buffering Keystroke handling Support for accesibility Actions Icons

JComponent features Example:

public void setBorder(Border aBorder) public Dimension getMinimumSize()

public Dimension getMaximumSize()public Dimension getPreferredSize()

public void setToolTipText(String txt) public void setAutoscrolls(boolean yesNo) public void registerKeyboardAction(ActionListener

anAction, KeyStroke aKeyStroke, int aCondition) etc.

Pattern: “Composite” Compose objects into tree structures to

represent part-whole hierarchies. Composite lets clients treat individual objects and compositions of objects uniformly.

Example: Graphical components. Containers can have many Simple components and other Containers.

From Client Side: No distinction between Simple Components to Containers.

COMPOSITE – Graphic Example

COMPOSITE – General Structure

COMPOSITE – Example object

Event Handling Delegation event model.

Event types Event processors Event listeners

Event

Event Processor / Component

Event Listener

Notifies Registers

Event Types Event Types

ActionEvent : Like Button clicked or the return key is pressed.

ChangeEvent : A value has changed. FocusEvent : Component gains or looses focus. ItemEvent : Selection of an item changed. KeyEvent : Key press or release ListDataEvent : Contents of a list change ListSelectionEvent : Selection in list changes MenuEvent : When a menu is selected or cancelled MouseEvent : WindowEvent : Window closing, iconifying, etc.

Event Listeners Customized programs for reacting to events.

Like : What to do when a button is clicked. One Event Processor can have more then one event

listener.Like : There can be a couple of Listeners for a button click.

Components that react to events must implement the appropriate interface.Like : In Button-click, the reacting object must be an implementation of ActionListener

There are adaptors for making Concrete empty implementation of Listeners.

Events in Swing If we have an event called EEE Event addition-removal functions are located mostly in

JComponent typesaddEEEListener(EEEListener listener)removeEEEListener(EEEListener listener)

The Listener interface type is interface EEEListener

The Abstract class of that interface (if there is one) isabstract class EEEAdapter

The Event get is in the object of class EEEEvent

Events in swing Event Class = ActionEvent

Listener Interface = ActionListenerFunctions = addActionListener(…)

removeActionListener(…)No Adapter.Who : JButton, JList, JTextField, JMenuItem, etc.

Event Class = AdjustmentEventListener Interface = AdjustmentListenerFunctions = addAdjustmentListener(…)

removeAdjustmentListener(…)No Adapter.Who : JScrollbar

Event Class = WindowEventListener Interface = WindowListenerFunctions = addWindowListener(…)

removeWindowListener(…)No Adapter.Who : JFrame, JDialog, JFileDialog, etc.

Many more: ComponentEvent, ContainerEvent, FocusEvent, KeyEvent, MouseEvent, ItemEvent, TextEvent, etc.

Example: Window with Event Handlerimport java.util.* ;import java.awt.* ;import java.awt.event.* ;import javax.swing.* ;class WindowCloser extends WindowAdapter // Indirectly implements WindowListener{ int i = 0 ; public void windowClosing(WindowEvent e)

{ Window win ; i++ ; if (i>=3) { win = e.getWindow() ; win.setVisible(false) ; win.dispose() ; System.exit(0) ; } } }

public class Windows extends JFrame {

public static void main(String[] args) {

JFrame win = new Windows() ;

win.addWindowListener(new WindowCloser()) ;

win.getContentPane().add(new Label("Hello"),"Center") ;

win.pack() ;

win.setVisible(true) ;

}

}

Example: Button with Action Event

package GUI;import java.awt.* ;import java.awt.event.* ;import javax.swing.* ;

public class HelloGoodbye extends JFrame implements ActionListener {

private static final String HELLO="Hello!" ; private static final String GOODBYE="GoodBye!" ; private String message = HELLO ; private JPanel counterPanel ; private JButton counterButton ; private JLabel counterLabel ; public HelloGoodbye() { super("HelloGoodbye") ; counterLabel = new

JLabel(message,SwingConstants.CENTER) ; counterButton = new

JButton("Click Me") ; counterButton.addActionListener(this) ; counterPanel = new JPanel() ; counterPanel.setBorder(

BorderFactory. createEmptyBorder(20,60,20,60)) ;

counterPanel.setLayout(new BorderLayout()) ; counterPanel.add(

counterLabel,BorderLayout.CENTER) ; counterPanel.add(

counterButton,BorderLayout.SOUTH) ; getContentPane().add(counterPanel) ; addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0) ; } } ) ; pack() ; setVisible(true) ; } public void actionPerformed(ActionEvent e) { if (message.equals(HELLO)) { message = GOODBYE ; } else { message = HELLO ; } counterLabel.setText(message) ; } public static void main(String[] args) { final HelloGoodbye app = new HelloGoodbye() ; }}

Event Queue

A. Event OccursB. Event Object CreatedC. Add Event to Queue

Event

Event Queue

Notifiy Processor / Component

Get Next Event

Determine Event Processor

Layout Managers Layout managers define how to lay out the

child components in a container. Each container type has a default Layout

manager. It can be replaced with an existing layout

manager or a custom one can be created.

Layout Managers Some layout Managers in AWT and Swing

BorderLayout BoxLayout CardLayout FlowLayout GridBagLayout GridLayout OverlayLayout ScrollpaneLayout ViewportLayout

Some containers have default layout managers JPanel : FlowLayout JScrollPane : ScrollPaneLayout JViewport : ViewportLayout etc.

Border Layout Exampleimport javax.swing.*;import java.awt.*;

public class BorderLayoutExample { public static void main(String[] args) {

JFrame f = new JFrame("Border Layout Example") ; Container c = f.getContentPane() ; c.setLayout(new BorderLayout()) ; // Default

c.add(BorderLayout.NORTH, new JButton("North")); c.add(BorderLayout.SOUTH, new JButton("South"));

c.add(BorderLayout.EAST, new JButton("East")); c.add(BorderLayout.WEST, new JButton("West")); c.add(BorderLayout.CENTER, new JButton("Center")); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE) ; f.pack() ; f.setVisible(true) ;

}}

Flow Layout Exampleimport javax.swing.*;import java.awt.*;

public class FlowLayoutExample { public static void main(String[] args) {

JFrame f = new JFrame("Flow Layout Example") ; Container c = f.getContentPane() ; c.setLayout(new FlowLayout()) ;

c.add(new JButton("North")); c.add(new JButton("South"));

c.add(new JButton("East")); c.add(new JButton("West")); c.add(new JButton("Center")); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE) ; f.pack() ; f.setVisible(true) ;

}}

MVC–Model View ControllerObserver pattern

MVC MVC : (Model View Controller) is used in building

User Interfaces. MVC consists of three kinds of objects

Model : Is the application object, or data. View : Its screen presentation Control : Controls how User interface reacts with the data.

MVC uses subscribe/notify protocol. Decoupling between Model and View, allows to

attach Multiple Views to a Model.

MVC

Example - Swing Swing components has Model-View-

Controller type of organization. For example :

JProgressBar uses BoundedRangeModel. public BoundedRangeModel getModel() ; public void setModel(BoundedRangeModel newModel)

;

JSlider as well uses BoundedRangeModel.

Example – BoundedRangeModel

import java.util.* ;import java.awt.* ;import java.awt.event.* ;import javax.swing.* ;public class ProgressModel extends JPanel { public ProgressModel() { JProgressBar progBar = new JProgressBar() ; progBar.setMinimum(0) ; progBar.setMaximum(100) ; progBar.setValue(0) ; JSlider slider = new JSlider() ; slider.setModel(progBar.getModel()) ; add(progBar) ; add(slider) ; } public Dimension getPreferredSize() { return new Dimension(300,100) ; }

public static void main(String[] args) {

JFrame f = new JFrame("Progress Model Example") ;

ProgressModel panel = new ProgressModel() ;

f.setForeground (Color.black) ;

f.setBackground (Color.lightGray) ;

f.setDefaultCloseOperation ( JFrame.EXIT_ON_CLOSE ) ;

f.getContentPane().add ( BorderLayout.CENTER,panel) ;

f.setSize(panel.getPreferredSize()) ;

f.show() ;

}

}

“OBSERVER”

“OBSERVER” Pattern Define a one-to-many dependency between objects so

that when one object changes state, all its dependents are notified and updated automatically.

The key objects are “subject” and “observer”. A “subject” can have many dependent “observer”s Whenever “suject” undergoes a change all “observer”s are

notified Each “observer” can query “subject” for synchronizing its

state “Publish”-“Subscribe” : “observer”s are subscribed to

“subject” and “subject” publishes or notifies the observers of any change.

OBSERVER

OBSERVER Participants

“Subject” Knows its observers. Methods for adding and removing “Observer”s

“Observer” Method for being updated

ConcreteSubject Stores state of interest Sends notification to “Observer”s when its state change

ConcreteObserver Has a reference to ConcreteSubject Its state must be consistent with subject’s state Implements Updating to keep its state consistent with subject’s state

OBSERVER

OBSERVER Who calls notify() or update() …

If Subject calls … Client Observers don’t have to remember to call every time there is a

change in Subject If Observers call

An Observer can make a list of changes and only then call the notify() Update() can pass as argument the change.

Push model : Subject sends observers detailed information about the change, whether they want it or not.

Pull model : Subject sends only a minimal notification, and observers ask for details.

Observers can specify interest on some changes when they subscribe.

Complex Swing ComponentsJTable, JTree, etc.

JTree A tree is a set of hierarchical nodes. The top of this hierarchy is called “root”. An element that does not have children is

called “leaf”. JTree nodes are managed by a “TreeModel”. “TreeCellRenderer” converts an object to its

visual representation in the tree.

JTree Example

TreeModel Methods Object getRoot() Object getChild(Object parent, int index) int getChildCount(Object parent) boolean isLeaf(Object node) void valueForPathChanged(TreePath path, Object newVal) int getIndexOfChild(Object parent, Object child) void addTreeModelListener(TreeModelListener l) void removeTreeModelListener(TreeModelListener l)

JTree constructors JTree() JTree(Object[] value) JTree(Vector value) JTree(Hashtable value) JTree(TreeNode root) JTree(TreeNode root, boolean

asksAllowsChildren) JTree(TreeModel newModel)

TreeNodes Default tree model uses objects of TreeNode to represent the nodes in the

tree. A default implementation of it is DefaultMutableTreeNode. TreeNode methods

TreeNode getChildAt(int childIndex) int getChildCount() TreeNode getParent() int getIndex(TreeNode node) boolean getAllowsChildren() boolean isLeaf() Enumeration children()

DefaultMutableTreeNode constructors DefaultMutableTreeNode() DefaultMutableTreeNode(Object userObject) DefaultMutableTreeNode(Object userObject, boolean allowsChildren)

JTree example

import javax.swing.* ;import javax.swing.tree.* ;import java.awt.event.* ;import java.awt.* ;import java.util.* ;public class TreeNodeExample extends JPanel {

public TreeNodeExample() {DefaultMutableTreeNode rootNode = new

DefaultMutableTreeNode("Categories") ;DefaultMutableTreeNode parentNode = new

DefaultMutableTreeNode("Metals") ;parentNode.add(new DefaultMutableTreeNode("Gold",false)) ;parentNode.add(new DefaultMutableTreeNode("Silver",false)) ;parentNode.add(new DefaultMutableTreeNode("Bronze",false)) ;parentNode.add(new DefaultMutableTreeNode("Copper",false)) ;parentNode.add(new DefaultMutableTreeNode("Iron",false)) ;parentNode.add(new DefaultMutableTreeNode("Platinium",false)) ;parentNode.add(new DefaultMutableTreeNode("Titanium",false)) ;rootNode.add(parentNode) ;parentNode = new DefaultMutableTreeNode("Companies") ;parentNode.add(new DefaultMutableTreeNode("Paradigm

Research",false)) ;parentNode.add(new DefaultMutableTreeNode("JavaSoft",false)) ;parentNode.add(new DefaultMutableTreeNode("Wiley Press",false)) ;rootNode.add(parentNode) ;setLayout(new BorderLayout());add(new JScrollPane(new JTree(rootNode)),"Center") ;

}

public Dimension getPreferredSize(){ return new Dimension(200,120) ; }

public static void main(String[]args) {JFrame frame = new JFrame("Tree Node Example") ;TreeNodeExample panel = new TreeNodeExample() ;frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE) ;frame.getContentPane().add(panel,"Center") ;frame.setSize(panel.getPreferredSize()) ;frame.setVisible(true) ;

} }

TreeModel Listener TreeModelListener methods

void treeNodesChanged(TreeModelEvent e) void treeNodesInserted(TreeModelEvent e) void treeNodesRemoved(TreeModelEvent e) void treeStructureChanged(TreeModelEvent e)

TreeModelEvent methods TreePath getTreePath() Object[] getPath() Object[] getChildren() int[] getChildIndices()

Custom Tree Model Example

import java.io.* ;

import java.util.* ;

class FileHolder {

File myFile ;

Vector children ;

public FileHolder(File f)

{ myFile = f ; }

public File getFile()

{ return myFile ; } public String toString() { return myFile.getName() ; }

public Vector getChildren() { if (myFile.isDirectory() && (children==null)) { int max=0; String list[] ; File curFile ; FileHolder curHolder ; children = new Vector() ; list = myFile.list() ; if (list!=null) max = list.length ; for (int i=0;i<max;++i) { curFile = new File(myFile,list[i]) ; curHolder = new FileHolder(curFile) ; children.addElement(curHolder) ; } } return children ; }}

Custom Tree Model Exampleimport javax.swing.* ;import javax.swing.tree.* ;import javax.swing.event.* ;import java.io.* ;import java.util.* ;class FileSystemTreeModel implements TreeModel { protected FileHolder root ; protected Vector listeners ; public FileSystemTreeModel(File r) { root = new FileHolder(r) ; listeners = new Vector() ; } public Object getRoot() { return root ; } public Object getChild(Object parent, int index) { Object retVal=null ; Vector children ; if (parent instanceof FileHolder) { children = ((FileHolder)parent).getChildren() ; if (children!=null) if (index<children.size()) retVal=children.elementAt(index) ; } return retVal ; } public int getChildCount(Object parent) { int retVal = 0 ; Vector children ; if (parent instanceof FileHolder) { children = ((FileHolder)parent).getChildren() ; if (children!=null) retVal = children.size() ; } return retVal ; }

public boolean isLeaf(Object node)

{ boolean retVal = true ;

File file ;

if (node instanceof FileHolder) {

file = ((FileHolder)node).getFile() ;

retVal = file.isFile() ;

}

return retVal ; }

public void valueForPathChanged(TreePath path, Object newVal)

{ }

public int getIndexOfChild(Object parent, Object child)

{ int retVal = -1 ;

Vector children ;

if (parent instanceof FileHolder) {

children = ((FileHolder)parent).getChildren() ;

if (children!=null)

retVal = children.indexOf(child) ;

}

return retVal ; }

public void addTreeModelListener(TreeModelListener l)

{ if ((l!=null)&&!listeners.contains(l))

listeners.addElement(l) ; }

public void removeTreeModelListener(TreeModelListener l)

{ listeners.removeElement(l) ; }

}

Custom Tree Model Exampleimport javax.swing.* ;import java.awt.event.* ;import java.awt.* ;import java.io.* ;import java.util.* ;public class FileTree extends JPanel { public FileTree(String startPath) { JTree tree = new JTree() ; tree.setModel(new FileSystemTreeModel(new File(startPath))) ; setLayout(new BorderLayout()) ; add(new JScrollPane(tree),"Center") ; } public Dimension getPreferredSize() { return new Dimension(250,200) ; } public static void main(String[]s) { JFrame frame = new JFrame("File Tree Example") ; FileTree panel = new FileTree(s.length>0?s[0]:"/") ; frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE) ; frame.getContentPane().add(panel,"Center") ; frame.setSize(panel.getPreferredSize()) ; frame.setVisible(true) ; }}

JTable JTable displays tabular data in rows and

columns. Header for the title of each column.

TableModel

TableModel Methods void addTableModelListener(TableModelListener l) void removeTableModelListener(TableModelListener l) int getRowCount() int getColumnCount() String getColumnName(int columnIndex) Class getColumnClass(int columnIndex) boolean isCellEditable(int rowIndex, int columnIndex) Object getValueAt(int rowIndex, int columnIndex) Object setValueAt(Object aValue, int rowIndex, int columnIndex)

AbstractTableModel (methods that must be implemented) int getRowCount() int getColumnCount() Object getValueAt(int rowIndex,int columnIndex)

TableModelListener TableModelListener methods

void tableChanged(TableModelEvent evt) TableModelEvent methods

int getColumn() int getFirstRow() int getLastRow() int getType()