The Java Foundation Classes (JFC) are a set of packages encompassing the following APIs: Abstract Window Toolkit (AWT): native

GUI components Swing: lightweight GUI components 2D: rendering two-dimensional shapes, text,

and images Accessibility: allowing compatibility with, for

example, screen readers and screen magnifiers

Provides basic UI components: Buttons, lists, menus, textfields, etc Event handling mechanism Clipboard and data transfer Image manipulation Font manipulation Graphics

Platform independence is achieved through peers, or native GUI components

java.awt Basic component functionalityjava.awt.accessibility Assistive technologiesjava.awt.color Colors and color spacesjava.awt.datatransfer Clipboard and data transfer supportjava.awt.dnd Drag and dropjava.awt.event Event classes and listenersjava.awt.font 2D API font packagejava.awt.geom 2D API geometry packagejava.awt.im Input methodsjava.awt.image Fundamental image manipulation classesjava.awt.peer Peer interfaces for component peersjava.awt.print 2D API support for printingjava.awt.swing Swing components

The first AWT (Java 1.0) was rolled out in an incredible 6 weeks using peers

Thus an AWT menu on the Solaris platform, for example, actually creates a Motif menu object as its peer

UI components that have peers are called heavyweight because they are rendered in their own (opaque)

windows and thus are expensive to use, they must be rectangular and cannot have

transparent backgrounds, and they are not amenable to being subclassed

Java Program

Java AWT

NativeWindowSystemPeers

A Java program creates and displays an AWT component,which creates and displays a native component, or peer.

AWT 1.1 introduced the notion of lightweight components which: are contained within a heavyweight

component's window do not have peers are rendered in their container's window

rather than one of their own do not incur performance penalties and can

have transparent backgrounds Almost all Swing components are

lightweight ones that extend either java.awt.Component or java.awt.Container

Object

Component

Container ButtonList

Scrollbar

Label

Canvas

WindowJComponent

Scrollpane

Swing does not replace the AWT; it is built on top of it

All 1.0 AWT components are heavyweight; corresponding Swing components are lightweight

Swing component names begin with ``J'': Component (AWT) vs. JComponent (Swing) Button (AWT) vs. JButton (Swing)

Always use Swing components; however, since Swing is built on top of AWT, you will need to know some AWT methods

JComponent

AbstractButton

JButton JMenuItem

JToggleButton

JCheckBox

JLabel

JList

JScrollBar

JFileChooser

Note that JComponents are containers JComponents do not extend their AWT

counterparts: For example, the JButton class is not a

subclass (direct or indirect) of Button However, some Swing components are

not JComponents For example, some Swing containers are

direct subclasses of their AWT counterparts

Container

JComponent Panel

ScrollPane

Window

Dialog Frame

Applet

Container

JComponent Panel

ScrollPaneWindow

Dialog Frame Applet

JDialog

JWindow

JFrame JApplet

JComponent

JLayeredPane JPanel

JScrollPane

JInternalFrame

JDesktopPane

JTable

JTree

void setBackground(Color c) void setForeground(Color c) void setEnabled(boolean b) void setVisible(boolean b) void setFont(Font f) void setSize(Dimension d) void setLocation(int x, int y)

All but setSize and setLocation are overridden by the JComponent class.

import java.awt.*;import javax.swing.*;

public class SwingTest {

public static void main(String[] args) { JFrame frame = new JFrame("Test Frame"); frame.setSize(new Dimension(300,200)); frame.setLocation(100,100); frame.setVisible(true); }

}

setSize and setLocation require java.awt.*; the rest require javax.swing.*

The JFrame constructor argument is used as a title The Dimension constructor takes an integer width

and height, respectively The setLocation method takes a pair of integer

coordinates (x,y) where (0,0) is the upper left corner of the display

The visibility of a JFrame is set to false by default

This window was managed by the K Desktop Environment (KDE)

Clicking the Close button (X) will cause the display to be hidden, but the program will continue since no listeners are set up yet

Can use ctl-C to kill the Java Virtual Machine

Color.black Color.blue Color.cyan Color.darkGray Color.gray Color.green Color.lightGray

Color.magenta Color.orange Color.pink Color.red Color.white Color.yellow

The java.awt.Color class has the following staticfields (data members):

import java.awt.*;import javax.swing.*;

public class SwingTest {

public static void main(String[] args) { JFrame frame = new JFrame("Test Frame"); frame.setSize(new Dimension(300,200)); frame.setLocation(100,100); Container contentPane = frame.getContentPane(); contentPane.setBackground(Color.red); frame.setVisible(true); }

}

Q: Why not just: frame.setBackground(Color.red); ?

A: In order to be lightweight, Swing's top-level window objects must be built on top of a lightweight AWT Container object introduced in version 1.1

This container is called a content pane Swing top-level window classes:

JWindow JFrame JApplet JDialog JInternalFrame

import java.awt.*;import javax.swing.*;

public class SwingTest {

public static void main(String[] args) { JFrame frame = new JFrame("Test Frame"); frame.setSize(new Dimension(300,200)); frame.setLocation(100,100); Container contentPane = frame.getContentPane(); JLabel label = new JLabel("HERE IS A LABEL"); contentPane.add(label, BorderLayout.NORTH); JButton button = new JButton("BUTTON"); contentPane.add(button, BorderLayout.SOUTH); frame.setVisible(true); }

}

Resized

Since the frame is a top-level Swing window, components must be added to its content pane

When components are added to a container, how they are placed is dependent upon the container's layout manager

The default layout manager for a JFrame is a BorderLayout manager (described later)

When adding to a container whose layout manager is BorderLayout, the second parameter should be a location defined in the BorderLayout class

import java.awt.*;import javax.swing.*;

public class SwingTest {

public static void main(String[] args) { JFrame frame = new JFrame("Test Frame"); frame.setSize(new Dimension(300,200)); frame.setLocation(100,100); Container contentPane = frame.getContentPane(); JLabel label = new JLabel("HERE IS A LABEL"); contentPane.add(label, BorderLayout.NORTH); JButton button = new JButton("BUTTON"); contentPane.add(button, BorderLayout.SOUTH); String[] options = {"Option 1", "Option 2", "Option 3"}; JList list = new JList(options); contentPane.add(list, BorderLayout.CENTER); frame.setVisible(true); }}

Note that "Option 3" has been selected.

public class SwingTest {

public static void main(String[] args) { JFrame frame = new JFrame("Test Frame"); frame.setSize(new Dimension(400,200)); frame.setLocation(100,100); Container contentPane = frame.getContentPane(); JLabel label = new JLabel("HERE IS A LABEL"); contentPane.add(label, BorderLayout.NORTH); JButton button = new JButton("BUTTON"); contentPane.add(button, BorderLayout.SOUTH);

String[] options = {"Option 1", "Option 2", "Option 3"}; JList list = new JList(options); contentPane.add(list, BorderLayout.CENTER);

JCheckBox cbox = new JCheckBox("Check"); contentPane.add(cbox, BorderLayout.WEST);

JSlider slider = new JSlider(); contentPane.add(slider, BorderLayout.EAST);

frame.setVisible(true); }}

A layout manager determines the location and size of components placed into a container

Different layout managers use different algorithms for determining size and location: BorderLayout: places at compass locations and

center FlowLayout: places components in rows, left to right GridLayout: places in rectangular grid BoxLayout: places in a single row or column

public class SwingTest {

public static void main(String[] args) { JFrame frame = new JFrame("Test Frame"); frame.setSize(new Dimension(300,200)); frame.setLocation(100,100); Container contentPane = frame.getContentPane();

contentPane.setLayout(new FlowLayout()); JLabel label = new JLabel("HERE IS A LABEL"); JButton button = new JButton("BUTTON"); String[] options = {"Option 1", "Option 2", "Option 3"}; JList list = new JList(options); JCheckBox cbox = new JCheckBox("Check"); JSlider slider = new JSlider(); contentPane.add(label); contentPane.add(button); contentPane.add(list); contentPane.add(cbox); contentPane.add(slider);

frame.setVisible(true); }

}

Resized

The default layout manager for content panes is BorderLayout. Recall that the following Swing components have content panes: JWindow JFrame JDialog JApplet JInternalFrame

The other Swing container is the JPanel, whose default layout manager is FlowLayout.

A JPanel object can be used for grouping components into a container, which can then be added to another container

The JPanel constructor with no arguments creates a panel with a FlowLayout manager

Another JPanel constructor takes any layout manager as an argument

A JPanel can also be used a a blank area for drawing custom graphics

JFrame frame = new JFrame("Test Frame"); frame.setSize(new Dimension(300,200)); frame.setLocation(100,100); Container contentPane = frame.getContentPane();

JLabel label = new JLabel("HERE ARE SOME BUTTONS", SwingConstants.CENTER);

JButton button1 = new JButton("BUTTON1"); JButton button2 = new JButton("BUTTON2"); JButton button3 = new JButton("BUTTON3"); JPanel panel = new JPanel(); panel.add(button1); panel.add(button2); panel.add(button3);

contentPane.add(label, BorderLayout.NORTH); contentPane.add(panel, BorderLayout.CENTER);

frame.setVisible(true);

Note use of SwingConstants.CENTER argumentin JLabel constructor.

JFrame frame = new JFrame("Test Frame"); frame.setSize(new Dimension(300,200)); frame.setLocation(100,100); Container contentPane = frame.getContentPane();

JLabel label = new JLabel("HERE ARE SOME BUTTONS", SwingConstants.CENTER);

JButton button1 = new JButton("BUTTON1"); JButton button2 = new JButton("BUTTON2"); JButton button3 = new JButton("BUTTON3"); JPanel panel = new JPanel(); panel.setLayout (new BoxLayout(panel, BoxLayout.Y_AXIS)); panel.add(button1); panel.add(button2); panel.add(button3);

contentPane.add(label, BorderLayout.NORTH); contentPane.add(panel, BorderLayout.CENTER);

frame.setVisible(true);

The button panel is to the west because no other component was placed there

The BoxLayout constructor requires both the component being laid out and either: BoxLayout.X_AXIS BoxLayout.Y_AXIS

Some layout constructors allow hgap and vgap, integers specifying the number of pixels separating components horizontally and vertically

FlowLayout allows the specification of whether the line of components should be left-justified, right-justified, or centered

new FlowLayout(int align)new FlowLayout(int align, int hgap, int vgap)

new BorderLayout(int hgap, int vgap)

new GridLayout(int rows, int cols)new GridLayout(int rows, int cols, int hgap, int vgap)

JFrame frame = new JFrame("Test Frame"); frame.setSize(new Dimension(300,200)); frame.setLocation(100,100); Container contentPane = frame.getContentPane(); LayoutManager lm = contentPane.getLayout(); ((BorderLayout)lm).setHgap(25);

JLabel label = new JLabel("HERE ARE SOME BUTTONS", SwingConstants.CENTER);

JButton button1 = new JButton("BUTTON1"); JButton button2 = new JButton("BUTTON2"); JButton button3 = new JButton("BUTTON3"); JPanel panel = new JPanel(); panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS)); panel.add(button1); panel.add(button2); panel.add(button3);

contentPane.add(label, BorderLayout.NORTH); contentPane.add(panel, BorderLayout.CENTER);

frame.setVisible(true);

The LayoutManager returned by getLayout() is an interface type that the BorderLayout class implements

The setHgap method we want is in the BorderLayout class

So we must cast the LayoutManager to BorderLayout in order to use setHgap

Layout managers often need to resize their components to make things fit For example, the widths and heights of

components in a BoxLayout are adjusted according to both preferred and maximum heights and widths

If you don't like the size of the components a layout manager comes up with, you may have to give sizing hints using the following methods from the JComponent class: void setMinimumSize(Dimension d) void setPreferredSize(Dimension d) void setMaximumSize(Dimension d)