Introduction to Swing Components Chapter 14

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Nov 3, 2013 (3 years and 10 months ago)

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Introduction to Swing Components

Chapter 14


Part of the Java Foundation Classes (JFC)


Provides a rich set of GUI components


Used to create a Java program with a
graphical user interface (GUI)


table controls, list controls, tree controls,
buttons, and labels, and so on…


In April 1997, JavaSoft announced the
Java Foundation Classes (JFC).


a major part of the JFC is a new set of user
interface components called Swing.

AWT

Swing

Accessibility

Java


2D

Drag

And

Drop


AWT


java.awt


java.awt.color


java.awt.datatransfer


java.awt.event


java.awt.font


java.awt.geom


java.awt.image


Swing


javax.accessibility



javax.swing



javax.swing.colorchoos
er



javax.swing.event



javax.swing.filechooser



javax.swing.plaf



javax.swing.table



javax.swing.text.html


javax.swing.tree


A GUI consists of different graphic
Component objects which are combined
into a hierarchy using Container objects.


Component class



An abstract class for GUI components such as menus,
buttons, labels, lists, etc.


Container



An abstract class that extends Component. Containers
can hold multiple components.



Container


Type of component that holds other components


Can treat group as single entity


Defined in
Container
class


Often takes form of window


Drag


Resize


Minimize


Restore


Close



Swing provides:


A wide variety of components (tables, trees, sliders,
progress bars, internal frame, …)


Swing components can have
tooltips

placed over
them


Arbitrary keyboard events can be bound to
components


Additional debugging support.


Support for parsing and displaying HTML based
information

JFrame

window
= new
JFrame
(
"
title

"

);


A
JFrame

is a Window with all of the
adornments
added


JFrame

inherits from
Frame, Window,
Container, Component,

and
Object


A
JFrame

provides the basic building block for
screen
-
oriented
applications

import
javax.swing
.*;


public class
SwingFrame

{


public static void main( String
args
[] ) {


JFrame

window
= new
JFrame
( "My First GUI Program" )
;



window.setVisible
(true
);


}

}


Set size and title

window.setSize
(200, 100);

window.setTitle
("My frame");


Close
JFrame


Click Close button


JFrame

becomes hidden and application keeps
running


Default behavior


To change this behavior


Use
setDefaultCloseOperation
()

method

window.setDefaultCloseOperation
(
JFrame.EXIT_ON_CLOSE

);


import
javax.swing
.*;

import
java.awt
.*;


public class
SwingFrame

{



public
static void main( String
args
[] ) {


JFrame

window
= new
JFrame
( "My First GUI Program" );


window.setDefaultCloseOperation
(
JFrame.EXIT_ON_CLOSE

);



window.setSize
( 250
, 150

);


window.setVisible
(true
);


}

}


JFrame
s have several panes:








Components are placed in the Content Pane

Glass pane

Layered pane

Menu bar

Content pane


JComponent


JComboBox, JLabel, JList,
JMenuBar, JPanel, JPopupMenu,
JScrollBar, JScrollPane, JTable,
JTree, JInternalFrame,
JOptionPane, JProgressBar,
JRootPane, JSeparator, JSlider,
JSplitPane, JTabbedPane, JToolBar,
JToolTip, Jviewport,
JColorChooser, JTextComponent, …

label
= new
JLabel
("text
",
JLabel.RIGHT

);

Font
typeSet

= new Font("Arial",
Font.BOLD
, 36 );



JLabels

are components that you can fill with
text.


When creating a label you can specify the initial
value and the alignment you wish to use within the
label.


You can use
getText
()

and
setText
()

to get
and change the value of the label
.


You can use
setFont
()

to change the font, style
and size of your text

import
javax.swing
.*;


public class
SwingFrame

{


public static void main( String
args
[] ) {


JFrame

window
= new
JFrame
( "My First GUI Program" )
;


JLabel

label = new
JLabel
( "Hello World" );


Font
typeSet

= new Font(
"Century",
Font.BOLD
, 28
);



label.setFont
(
typeSet
);


window.add
( label
);


window.setSize
(250, 100);



window.setDefaultCloseOperation
(
JFrame.EXIT_ON_CLOSE
);


window.setVisible
(true
);


}

}


JButton

extends
Component

, displays a
string, and delivers an
ActionEvent

for
each mouse click.


Normally buttons are displayed with a
border


In addition to text,
JButtons

can also
display icons

button = new JButton( ”text“ )
;

import
javax.swing
.*;


public class
SwingFrame

{


public static void main( String
args
[] ) {


JFrame

window
= new
JFrame
(
"My First GUI Program"
);



JButton

button = new
JButton
( "Click Me!!" );



window.add
( button
);


window.setSize
(250, 100);


window.setDefaultCloseOperation
(
JFrame.EXIT_ON_CLOSE
);



win.setVisible
(true);


}

}


Layout Manager


An interface that defines methods for
positioning and sizing objects within a
container. Java defines several default
implementations of
LayoutManager
.


Geometrical placement in a Container is
controlled by a
LayoutManager

object

19


Containers may contain components (which
means containers can contain containers!!).


All containers come equipped with a layout
manager which positions and shapes (lays
out) the container's components.


Much of the action in Swing occurs between
components, containers, and their layout
managers.

20


Layouts allow you to format components on the
screen in a platform
-
independent way


The standard JDK provides many classes that
implement the
LayoutManager

interface,
including:


FlowLayout



GridLayout



BorderLayout



BoxLayout


CardLayout



OverlayLayout


GridBagLayout


21


Invoke
the
setLayout
()

method on the
container to use the new layout.



setLayout
( new
FlowLayout
() );



The
layout manager should be established
before any components are added to the
container


JFrame

will otherwise stack all components on
top of each other

22


When
you add components to the screen, they
flow left to right (centered) based on the order
added and the width of the screen.


Very similar to word wrap and full justification on
a word processor.


If the screen is resized, the components' flow will
change based on the new width and height


FlowLayout

is the default layout for the
JPanel

class.


import
javax.swing
.*;

import java.awt.*;


public class
LayOut

{


public static void main( String
args
[] ) {




JFrame

window = new
JFrame
( "Layout Program" );


JLabel

title = new
JLabel
( "Layout Example" );


JLabel

name = new
JLabel
( "Enter your name" );


JTextField

textInput

= new
JTextField
( 12 );


JButton

button = new
JButton
( "Enter your name" );




window.setSize
(200, 150);


window.setDefaultCloseOperation
(
JFrame.EXIT_ON_CLOSE
);


window.setVisible
(true);




window.setLayout
( new
FlowLayout
() );


window.add
( title );


window.add
( name );


window.add
(
textInput

);


window.add
( button );


}

}


24

import
javax.swing
.*;

import
java.awt
.*;


public class
ShowFlowLayout

{


public static void main( String
args
[] ) {


JFrame

win = new
JFrame
( "My First GUI Program" );


win.setDefaultCloseOperation
(
JFrame.EXIT_ON_CLOSE

);



win.getContentPane
().
setLayout
( new
FlowLayout
() );



for (
int

i

= 0;
i

< 10;
i
++ ) {



win.getContentPane
().add(



new
JButton
(
String.valueOf
(
i

) ) );


}




win.setVisible
(true);


}

}

25

You can resize with the mouse and the
buttons will move to fill in the space


Programs respond to events that are
generated
outside

the control of the program


User types a key


The left mouse button is pressed


A CD is removed from the CD drive


When an event occurs, it is handled by an
event handler


Event driven programming involves

1.
writing the handlers, and

2.
arranging for the handler to be notified when
certain events occur


An
event

is represented by an object that
gives information about the event and identifies
the event source


Event sources are typically components, but other
kinds of objects can also be event sources


A
listener

is an object that wants to be
notified when a particular event occurs


An event source can have multiple listeners
registered on it


A single listener can register with multiple event
sources


In order for an object to be notified when a
particular event occurs, the object

1.
must implement the appropriate
Listener

interface

2.
must be
registered

as an event listener on the
appropriate event source


Action

Listener Type

User clicks a button, presses return while
typing in a text field, or chooses a menu
item

ActionListener

Users closes a frame (main window)

WindowListener

User presses a mouse button while the
cursor is over a component

MouseListener

User moves the mouse over a component

MouseMotionListener

A component becomes visible

ComponentListener

A component gets the keyboard focus

FocusListener

A table of list selection changes

ListSelectionListener