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Java ProgrammingIntroduction to Swing Components
Chapter 14
What is Java Swing?
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…
Java Foundation Classes
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 AccessibilityJava 2D
DragAndDrop
GUI Packages
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.colorchooser javax.swing.event javax.swing.filechooser javax.swing.plaf javax.swing.table javax.swing.text.html javax.swing.tree
Components
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.
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 Features
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 " );
JFrames
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
Creating a JFrame
import javax.swing.*;
public class SwingFrame { public static void main( String args[] ) {
JFrame window = new JFrame( "My First GUI Program" );
window.setVisible(true); }}
JFrames
Set size and titlewindow.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() methodwindow.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
Creating a JFrame
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
JFrames have several panes:
Components are placed in the Content Pane
Glass pane
Layered pane
Menu bar
Content pane
Swing Components
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 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
JLabelsimport 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);
}}
JButtons
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“ );
Buttonsimport 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
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
Components, Containers, and Layout Managers
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
Layout Managers 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
Changing the Layout
22
FlowLayout 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
Flow Layout
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
FlowLayout
You can resize with the mouse and the buttons will move to fill in the space
Event Driven Programming
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
Event Handling
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
Listeners
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
Swing Listeners
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