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Intro to Swing
GUI development
Swing is
• A big API
• Built on AWT (another big API)
• Used for GUI's
Swing class hierarchy fragment
Component
AWT
Swing
Container
Frame
JFrame
JApplet
JComponent
Window
Panel
Dialog
JWindow
JDialog
JLabel
JPanel
JTable
JTree
Other basic classes
• AWT classes defined in the package
java.awt
–
–
–
–
Color, ( an immutable class)
Point,
Dimension,
Font
JOptionPane Examples
JComboBox

A JComboBox looks like a text field with an
arrow next to it. If you click on the arrow,
the list of possible values is displayed.

If the Jcombobox is set to be editable, then
you can edit the current selection as if it
was a text field.

Only one item can be selected at a time.
You can retrieve it by calling:
getSelectedItem method.

Add the choice items to the end of the list
with the addItem method.
Progress Bar
• Displays progress of operation
– Can be used like a gauge
• Usage:
– Initialize
JProgressBar progressBar = new JProgressBar();
progressBar.setMinimum(0);
progressBar.setMaximum(numberSubOperations);
– Go
progressBar.setValue(progressBar.getMinimum());
for (int i = 0; i < numberSubOperations; i++) {
progressBar.setValue(i);
performSubOperation(i);
}
Intro to The Progress Dialog
Dynamic Feedback
Why Dynamic Feedback?
• Users interact more smoothly with your
application if you keep them informed
about the application's state.
– Progress animation--an indicator such as a
progress bar that shows what percentage of an
operation is complete
When?
• Use a progress bar whenever users are
blocked from interacting with the
application for more than 6 seconds.
Use
• Users cannot interact with a progress bar.
• Update the progress bar to show the proportion
completed at least every 4 seconds.
• If you overestimate how much is already done,
the progress bar can remain at 99 percent until the
task is complete.
• If you underestimate how much is already done,
fill the remaining portion of the progress bar when
the operation completes.
• The percentage done should never decrease.
Swing class hierarchy fragment
Component
AWT
Swing
Container
Frame
JFrame
JApplet
JComponent
Window
Panel
Dialog
JWindow
JDialog
JLabel
JPanel
JTable
JTree
Progress Bar
• Displays progress of operation
– Can be used like a gauge
• Usage:
– Initialize
JProgressBar progressBar = new JProgressBar();
progressBar.setMinimum(0);
progressBar.setMaximum(numberSubOperations);
– Go
progressBar.setValue(progressBar.getMinimum());
for (int i = 0; i < numberSubOperations; i++) {
progressBar.setValue(i);
performSubOperation(i);
}
JProgressBar Methods
javax.swing.JComponent
javax.swing.JProgressBar
+JProgressBar()
Creates a horizontal progress bar with min 0 and max 100.
+JProgressBar(min: int, max: int)
Creates a horizontal progress bar with specified min and max.
+JProgressBar(orient: int)
Creates a progress bar with min 0 and max 100 and a specified orientation.
+JProgressBar(orient: int, min: int,
max: int)
Creates a progress bar with a specified orientation, min, and max.
+getMaximum(): int
Gets the maximum value. (default: 100)
+setMaximum(n: int): void
Sets a new maximum value.
+getMinimum(): int
Gets the minimum value. (default: 0)
+setMinimum(n: int): void
Sets a new minimum value.
+getOrientation(): int
Gets the orientation value. (default: HORIZONTAL)
+setOrientation(orient: int): void
Sets a new minimum value.
+getPercentComplete():double
Returns the percent complete for the progress bar. 0 <= a value <= 1.0.
+getValus(): int
Returns the progress bar's current value
+setValus(n: int): void
Sets the progress bar's current value.
+getString(): String
Returns the current value of the progress string.
+setString(s: String): void
Sets the value of the progress string.
+isStringPainted(): Boolean
Returns the value of the stringPainted property.
+setStringPainted(b: boolean): void Sets the value of the stringPainted property, which determines whether the
progress bar should render a progress percentage string. (default: false)
Example: JProgressBar Demo
Objective: Write a GUI
application that lets you copy
files. A progress bar is used to
show the progress of the copying
operation.
CopyFile
Run
Basic Controls
• Menu related classes
The Components
• A subclass of the java.awt.Component class
is called a Component
• A Component has a size, color, etc.
• A Component can normally be painted.
• When a component is painted it is visible on
the screen.
Component Subclasses
•
•
•
•
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•
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Container extends Component
Button extends Component
Window extends Container
Frame extends a Window
Dialog extends a Window
Panel extends a Container
Applet extends a Panel, etc.
Swing and AWT
• Swing is built on JComponent.
• JComponent extends Component
• JLabel, JButton, JCheckbox, etc all extend
JComponent
• Why?
Why does JComponent extend
Component?
•
•
•
•
Swing uses LightWeight Components!
AWT uses HeavyWeight components!
What is the difference?
What is so good about a LightWeight
Component?
• What are the drawbacks?
Do I still need AWT when using
Swing?
• Yes!
• AWT has many useful tools.
• Taken together they form a Framework.
Basic components to gather input
• JButton
• JCheckBox
a toggled on/off button displaying state
to user.
• JRadioButton
state to user.
a toggled on/off button displaying its
basic components
• JComboBox
a drop-down list with optional editable
text field. The user can key in a value or select a value
from drop-down list.
• Jlist
list.
allows a user to select one or more items from a
• Jmenu
popup list of items from which the user can
select.
• Jslider lets user select a value by sliding a knob.
• JTextField area for entering a single line of input.
Basic components to present information
• JLabel
contains text string, an image, or both.
• JProgressBar
communicates progress of some work.
• JToolTip describes purpose of another component.
• JTree
a component that displays hierarchical data in outline form.
• JTable
a component user to edit and display data in a twodimensional grid.
• JTextArea, JTextPane, JEditorPane
– define multi-line areas for displaying, entering, and editing text.
Swing components
Container
• Component that can contain other components and
containers.
Component
Container
JCom ponent

has
Intermediate components
• Used to organize and position other
components.
–
–
–
–
JPanel container of components.
JScrollPane panel with scrollbars.
JSplitPane divides two components graphically.
JTabbedPane lets the user switch between a group of
components by clicking on a labeled tab;
– JToolBar used for displaying a set of commonly used controls.
Example of component
organization
The following creates a JPanel and adds two buttons, labeled
“on” and “off.”
JPanel p = new JPanel();
p.add(new JButton("on"));
p.add(new JButton("off"));
• Wherever this panel is used, it will present the two
buttons.
Getting the screen size
public static Dimension getSize() {
Toolkit t = Toolkit.getDefaultToolkit();
return t.getScreenSize();
}
An example of AWT usage
public class Screen {
public static int getDpi() {
Toolkit t =
Toolkit.getDefaultToolkit();
return t.getScreenResolution();
}
Top-level container
• It’s not contained in any other container.
• provide
screen
area
where
components can display themselves.
other
– JApplet, JDialog, JFrame, and JWindow are
commonly used as top-level containers.
JFrame
• It’s a window with title, border, (optional)
menu bar and user-specified components.
• It can be moved, resized, iconified.
• It is not a subclass of JComponent.
• Delegates responsibility of managing userspecified components to a content pane, an
instance of JPanel.
Jframe
Jframe
Jframe internal structure
JFrame
• To add a component to a JFrame, add it to the
content pane:
JFrame f = new JFrame("A Frame");
JButton b = new JButton("Press");
Container cp = f.getContentPane();
cp.add(b)
JFrame components are in its
content pane.
JFrame
content pane
Container

Component
Swing vs AWT
• Swing has lightweight
components
• Light weight
components have no
peers
• Look and feel
variations available
• Swing is SLOW
• AWT is heavyweight
• heavyweight comps
require peers.
• Always looks like the
platform it runs on.
• AWT is FAST
Simple Output, a message dialog
public static void messageDialog(Object o) {
JOptionPane.showMessageDialog(null, o);
}
Simple Input
public class In {
public static String getString(Object o) {
return JOptionPane.showInputDialog(o);
}
How do we get an int?
Getting an Int
public static int getInt(Object o) {
return Integer.parseInt(
getString(o));
}
JList
– a component that allows a user to select one or
more elements from a list
String[] data = {"one", "two", ...};
JList list = new JList(data);
JList
– requires a ListSelectionListener that implements
public void valueChanged(ListSelectionEvent e) {
if (e.getValueIsAdjusting() == false) {
//selected: list.getSelectedValue()
}
}
– selection mode can be set to single, single interval, or
multiple interval
•
list.setSelectionMode(ListSelectionModel.SINGLE
_SELECTION);
Lists can be dynamic
– suppose you want the list to change during
execution of the program
– use a ListModel (normally DefaultListModel)
to contain the data
dynamic jlist
– create the list and pass in the ListModel as input
– add or remove elements in the ListModel
– the GUI will update the list dynamically
DefaultListModel listModel = new
DefaultListModel();
JList list = new JList(listModel);
listModel.addElement(object);
listModel.removeElement(i);
Scroll Panes
– sometimes the list will be too long to display in
the GUI
– Solution: display the list inside a JScrollPane
•
•
•
•
create a scroll pane containing the list
state how many rows you want to display
display the scroll pane, not the list
everything else is as before
jsp
JScrollPane sp = new
JScrollPane(list);
list.setVisibleRowCount(5);
add(sp);
Atomic IO
• Atomic actions happen all at once.
• Event driven call-backs can complicate
code.
• EmployeeRecord = getEmployeeRecord();
• How is getEmployeeRecord implemented?
JDialog
• Used to create custom dialog windows.
A Jdialog
– a top-level window.
– has an owner, generally a frame.
– It delegates component management to a
content pane, to which components are added.
– It’s displayed by invoking its setVisible
method with an argument of true, and is
hidden by invoking its setVisible method
with an argument of false
JDialog
• A typical constructor is specified as follows:
 Provides an object to create custom views to get or
present data.
public JDialog (Frame owner, String title,
boolean modal)
Implementing getXXX
• get data –
–
–
–
–
from a file
from the web
from the user
from …
• Hiding how the data is obtain encapuslates
complexity.
JColorChooser dialogs
• JColorChooser presents a pane of controls that allow
a user to select and manipulate a color.
Error Control
• int I = getInt(“enter an int [1..10]”,1,10);
• The getInt function protects the range on the
int. If the value is not correct, we prompt
the user again.
• The RHS waits for the assignment to
complete
JFileChooser
• Swing provides a file
chooser implemented
in 100% pure Java
•
The JFileChooser can display open, save and
custom dialogs
– showOpenDialog (JComponent)
– showSaveDialog (JComponent)
– showDialog (JComponent,
String)
•
JFileChooser allows multiple files to be
selected by setting the MuliSelectionEnabled
property to true
– setMultiSelectionEnabled(tr
ue);
FileChooser
JFileChooser directory = new JFileChooser();
directory.setCurrentDirectory(new File(“.”));
directory.showOpenDialog(this); //open dialog
File file = directory.getSelectedFile();
JFileChooser.getSelectedFiles
•
JFileChooser.getSelectedFiles can be called to get an array of the selected files
– File[] files = f.getSelectedFiles();
•
The JFileChooser abstracts the file view from the chooser using the
javax.swing.filechooser.JFileView abstract class
You can write your own file view by subclassing JFileView and passing it to the
JFileChooser
– f.setFileView (new ImageFileView());
•
•
•
One method of the JFileView returns an icon
This can be overridden to display different icons for different types of files in the
chooser
But how do you select a directory?
• Can JFileChooser select a directory?
• What about JTree?
Get a Directory
A Directory Chooser
public static File getReadDirFile(String
prompt) {
String dir =
DirectoryChooser.getDirectory(prompt);
if (dir==null) return null;
File f = new File(dir);
return f;
}
Layouts
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What is a layout manager?
What does a layout manager do?
What does a layout manager need?
Why do I need layouts?
Can I do GUI's without layouts?
Can you name a few layouts?
Some simple layouts
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FlowLayout
GridLayout
BorderLayout
BoxLayout
GridBagLayout….
What are these layouts for?
Adding Components via Layouts
Gui.layouts
• DialogLayout
ParagraphLayout
Simple ParagraphLayout
ParagraphLayout
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public static void main(String[] args) {
ClosableJFrame cf = new ClosableJFrame();
Container c = cf.getContentPane();
c.setLayout(new ParagraphLayout());
c.add(new JLabel("Name:"));
c.add(new JTextField(20));
c.add(new
JLabel("Name:"),ParagraphLayout.NEW_PARAGRAPH);
c.add(new JTextField(20));
cf.pack();
cf.setVisible(true);
}
PreferredSizeGridLayout
GridLayout ignores preferred size
How do I use
PreferredSizeGridLayout?
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public static void PreferredSizeGridLayoutExample() {
JFrame jf = new JFrame();
Container c = jf.getContentPane();
PreferredSizeGridLayout psgl =
new PreferredSizeGridLayout(0, 2, 0, 0);
psgl.setBoundableInterface(new BoundableComponentPlacement());
c.setLayout(psgl);
for (int i = 0; i < 5; i++) {
//rb.setAlignment((int)(Math.random()*8+1));
c.add(new RunButton("ok" + i) {
public void run() {
}
});
c.add(new RunButton("Cancel" + i) {
public void run() {
}
});
}
jf.setSize(200, 200);
jf.setVisible(true);
}
The following line switches
automatically to GridLayout
• psgl.setBoundableInterface(new
BoundableComponentPlacement());
PreferredSize
• Call:
• Dimension getPreferredSize(){…}
• To get the preferred size of any component.
VerticalFlowLayout
What is a layout manager?
• Responsible for positioning and resizing
components.
• LayoutManager is an interface that resides
in the java.awt.
Why do I need a Layout
Manager?
• You don't need a LayoutManager.
• You can set the Layout to null.
• You can reposition and resize all
components your self.
Why is a LayoutManager useful?
• Saves labor?
• Keeps the layout resolution versatile.
• keeps the interface flexible.
How does a LayoutManger
work?
• Every layout manager works differently.
– Typically, they get components dimensions
– components dimensions are used to properly
size and place the components.
Components implement:
Dimension getMinimumSize();
Dimension getMaximumSize();
Dimension getPreferredSize();
What if you don't like your
LayoutManager?
• Write your own!
• GridLayout ignores the min and max and
preferred sizes! It takes the available space
and evenly divides it among all the
components.
• All components are grown to the available
space.
GridLayout
FlowLayout
BoxLayout
keeps min and max size correct. Also centers
alignment
Options passed to the constructor
• X_AXIS - Components are laid out
horizontally from left to right.
• Y_AXIS - Components are laid out
vertically from top to bottom.
Custom layout managers (1)
• Ensure no existing manager does the job
– GridBagLayout / BoxLayout
– Layout manager downloads
Custom layout managers (2)
• Create class which implements Layout Manager
interface
– e.g. public class myManager implements LayoutManager
• Must have 5 methods required by interface
–
–
–
–
–
void addLayoutComponent(String, Component)
void removeLayoutComponent(Component)
Dimension preferredLayoutSize(Container)
Dimension minimumLayoutSize(Container)
Void layoutContainer(Container)
• See below URL for more documentation
– http://java.sun.com/docs/books/tutorial/uiswing/layout/custom.html
How do I combine GridLayout
with Preferred Size?
• I want a fixed number of rows or columns.
• I want to use the preferred size of each
component.
• I want to resize the components only if I
don't have enough room.
• I don't want components to fill all available
space.
Make your own LayoutManager!
• PreferredSizeGridLayout!
Using a custom layout manager
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•
public static void main(String[] args) {
ClosableJFrame cj = new ClosableJFrame();
Container c = cj.getContentPane();
c.setLayout(new VerticalFlowLayout(0,5));
for (int j = 0; j < 30; j++)
for (int i = 0; i < 10; i++) {
c.add(new RunLabel("Test#" + j + "," + i) {
•
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•
public void run() {
System.out.println(getText());
}
});
}
cj.setSize(200, 200);
cj.show();
}
Vertical Flow
Building An AddressBook Index
JTree
JTree Example
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.
TreeModel
• Hierarchical data
•
•
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•
•
Parents
Children
Siblings
Ancestors
Descendents
TreeModel
•
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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
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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
–
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–
–
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
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–
–
–
TreePath getTreePath()
Object[] getPath()
Object[] getChildren()
int[] getChildIndices()
Custom TreeModel
Implementation
• Implement interface TreeModel
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 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 ;
}
public String toString()
{ return myFile.getName() ; }
}
Custom Tree Model Example
import 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 Example
import 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) ; }
}
Jtree
DefaultTreeModel
• Interface TreeModel
– Declares methods for representing tree structure
• Class DefaultTreeModel
– Default TreeModel implementation
• TreeNode
• MutableTreeNode
• DefaultMutableTreeNode
JTree Architecture
«interface»
TreeModel
getRoot() : Object
getChildCount(in parent : Object) : int
getChild(in parent : Object, in index : int) : Object
getIndexOfChild(in parent : Object, in child : Object) : int
isLeaf(in node : Object) : boolean
valueForPathChanged(in Parameter1)
model
uiDelegate
JTree
TreeUI
*
«interface»
RowMapper
*
BasicTreeUI
1
«interface»
TreeNode
DefaultTreeModel
root
treePathMapping
AbstractLayoutCache
1
*
«interface»
MutableTreeNode
0..*
FixedHeightLayoutCache
DefaultMutableTreeNode
children
parent
VariableHeightLayoutCache
TreePaths (1)
lastPathComponent
parentPath
TreePaths (2)
• A child TreePath prevents all of its ancestors from
being gc’d
• Used throughout JTree as a unique address for a
tree node
• Allows equal() node objects to be used in the
same tree
• Some duplicate functionality with the data model
– trace node parentage
– indent level
– higher speed, more memory
JTree expandedState Cache
• Treepath used as key, value is Boolean
• Cache entry is not removed when node is collapsed
• Child entry is not removed if parent is collapsed
Boolean.TRUE
– JTree "remembers" expansion state of child nodes
Boolean.TRUE
Boolean.TRUE
Boolean.TRUE
JTree Layout Cache
• BasicTreeUI treePathMapping table
• Position and bounding box info for visible
nodes
• VariableHeightLayoutCache
– Is JTree default
– Caches all visible nodes
• FixedHeightLayoutCache
– Caches only expanded visible nodes
– Only enabled if JTree largeModel = true and
rows are explicitly set to a fixed height
JTree Caching Summary
expanded
state
previously expanded
fixed
height
variable
height
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 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 ;
}
public String toString()
{ return myFile.getName() ; }
}
Custom Tree Model Example
import 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 Example
import 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) ; }
}
Class: javax.swing.JTable
Swing Component
• displays data in table
• edit the data
Why do we need a table?
• The JTable component is useful for
presenting information of a tabular
nature
JTable properties
– Column is the basic unit of the Table.
– Row collection of columns
– Cell the location of data.
Architecture
•
•
•
•
MVC (Model-View-Controller)
Model:data of the components.
View:visual representation.
Controller:describe how the component
interacts with user.
MVC
Model Class
View Class
Data Accessor
Methods
Display Methods
Controller Class
Event Handling
Methods
MVC
• MVC paradigm
– Model
• Data storage, no presentation elements
– View
• No data storage, presentation elements
– Controller like a mediator
• Glue to tie the Model and the view together
Why use MVC?
• Modular design
• Consistency
• Complexity hiding
Constructors:
•
•
•
•
•
JTable( ) - JTable( int rows, int columns )
JTable( Object[ ][ ] rowData, Object[ ] columnNames )
JTable( Vector rowData, Vector columnNames )
JTable( TableModel model )
JTable( TableModel model,
TableColumnModel tcModel )
• JTable( TableModel model,
TableColumnModel tcModel,
ListSelectionModel lsModel )
Object[][] data = {{“Mary”, “Campione”,
“Snowboarding”, new Integer(5), new
Boolean(false)},{“Alison”, “Huml”,
“Rowing”, new Integer(3), new
Boolean(true)},{“Kathy”, “Walrath”,
“Chasing Toddlers”, new Integer(2),
new Boolean(false)},{“Mark”,
“Andrews”, “Speed Reading”, new
Integer(20), new
Boolean(true)},{“Angela”, “Lih”,
“Teaching high school”, new
Integer(4), new Boolean(false)}
};
String[] columnNames =
{
“First Name”,
“Last Name”,
“Sport”,
“# of Years”,
“Vegetarian”
};
JTable table = new JTable(data,
columnNames);
Interfaces
• TableColumnModel manages column
selection and spacing
• TableModel provides data.
Events
• TableColumnEvent caused by column
model changed.
• TableModelEvent caused by TableModel
changed
Change Width
TableColumn column;
for (int i = 0; i < 5; i++)
{
column =
table.getColumnModel().getColumn(i);
if (i == 2)
column.setPreferredWidth(100);
else
column.setPreferredWidth(50);
}
To change column widths
TableColumn column = null;
for (int i = 0; i < 5; i++) {
column = table.getColumnModel().getColumn(i);
if (i == 2) {
column.setPreferredWidth(100); //second column is
bigger
} else {
column.setPreferredWidth(50);
}
}
Build Model
TableModel tm = new AbstractTableModel()
{
public void getColumnCount()
{
return columnNames.length;
}
public void getRowCount()
{
return data.length;
}
public Object getValueAt(int row, int col)
{
return data[row][col];
}
public Class getColumnClass(int col)
{
return getValueAt(0, col).getClass();
}
Put the JTable in a JScrollPane
• This automatically deals space for the
header and does the right things!
Split pane
• Allows user-controlled resizing of two
components
• Can move divider programmatically with
setDividierLocation
– int parameter
• absolute position
– float parameter
• percentage
Tabbed Pane
• Tabbed panel control
• Similar to using CardLayout with buttons
for selecting cards
• Use addTab to add components/panels
The JDesktopPane
• Parent JLayeredPane.
• Can hold multiple overlapping internal
frames.
• Internal frames may be dragged, resized,
iconified.
• events handled by DesktopManager.
JDesktopPane Pro
• more window behavior control over than
JFrames.
• Can control minimization,
• Can control window look and feel.
• Appearance same on all platforms, easily
configurable.
Cons
• Requires more management.
• Can’t just add components without saying
where.
• Minimization prefs.
JDesktopPane and
JInternalFrame
• Multiple-document interface
– A main window (called the parent window)
contains other windows (called child windows)
– Manages several open documents that are being
processed in parallel
– Implemented by Swing’s JDesktopPane and
JInternalFrame
Using JInternalFrame
• Main constructor
– public JInternalFrame(String title,
boolean resizable,
boolean closeable,
boolean maximizable,
boolean iconifiable)
• Other useful methods
– moveToFront
– moveToBack
Internal Frames: Example Code
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class JInternalFrames extends JFrame {
public static void main(String[] args) {
new JInternalFrames();
}
public JInternalFrames() {
super("Multiple Document Interface");
WindowUtilities.setNativeLookAndFeel();
Internal Frames: Example Code
(Continued)
JDesktopPane desktop = new
JDesktopPane();
desktop.setBackground(Color.white);
content.add(desktop,
BorderLayout.CENTER);
setSize(450, 400);
for(int i=0; i<5; i++) {
JInternalFrame frame
= new JInternalFrame(("Internal Frame
" + i),
true, true,
true, true);
frame.setLocation(i*50+10, i*50+10);
Internal Frames:
Example Output
Internal Frames
Minimize
Maximize
Close
Outline
• DeskTo
pTest.ja
va
• (2 of
3)
Minimized internal frames
Position the mouse over any corner of a child window to
resize the window (if resizing is allowed).
Maximized internal frame
Outline
• DeskTo
pTest.ja
va
• (3 of
3)
Extra Fields in JInternalFrame
• closable, closed, desktopIcon, desktopPane,
frameIcon, icon, iconifiable, layer,
layeredPane, maximizable, maximum,
resizable, selected