java.awt

Some components fire events when a user interacts with the components. The AWTEvent class and its subclasses are used to represent the events that AWT components can fire. See AWTEvent for a description of the AWT event model.

A container is a component that can contain components and other containers. A con tainer can also have a layout manager that controls the visual placement of components in the container. The AWT package contains several layout manager classes and an interface for building your own layout manager. See Container and LayoutManager for more information.

Each {@code Component} object is limited in its maximum size and its location because the values are stored as an integer. Also, a platform may further restrict maximum size and location coordinates. The exact maximum values are dependent on the platform. There is no way to change these maximum values, either in Java code or in native code. These limitations also impose restrictions on component layout. If the bounds of a Component object exceed a platform limit, there is no way to properly arrange them within a Container object. The object's bounds are defined by any object's coordinate in combination with its size on a respective axis.

Additional Specification

• The AWT Focus Subsystem
• The AWT Modality

This is a very useful mechanism for avoiding deadlocks.

The event masks defined in this class are needed by Component subclasses which are using Component.enableEvents() to select for event types not selected by registered listeners.

The following example illustrates how to use this class:

 public myComponent extends Component {
 ActionListener actionListener = null;
 public synchronized void addActionListener(ActionListener l) {
 actionListener = AWTEventMulticaster.add(actionListener, l);
 }
 public synchronized void removeActionListener(ActionListener l) {
 actionListener = AWTEventMulticaster.remove(actionListener, l);
 }
 public void processEvent(AWTEvent e) {
 // when event occurs which causes "action" semantic
 ActionListener listener = actionListener;
 if (listener != null) {
 listener.actionPerformed(new ActionEvent());
 }
 }
 }
 

The target name is the name of the AWT permission (see below).

width

The pen width, measured perpendicularly to the pen trajectory.

end caps

The decoration applied to the ends of unclosed subpaths and dash segments.

The following code example creates a set of check boxes in a grid layout:

 setLayout(new GridLayout(3, 1));
 add(new Checkbox("one", null, true));
 add(new Checkbox("two"));
 add(new Checkbox("three"));
 

This image depicts the check boxes and grid layout created by this code example:

The button labeled one is in the "on" state, and the other two are in the "off" state.

The following picture depicts a menu which contains an instance of CheckBoxMenuItem:

Choice.java

Components added to a container are tracked in a list.

Supported operations include:

• launching the user-default browser to show a specified URI;
• launching the user-default mail client with an optional mailto URI;
• launching a registered application to open, edit or print a specified file.

This class provides methods corresponding to these operations.

It encapsulates asynchronous event dispatch machinery which extracts events from the queue and dispatches them by calling EventQueue.dispatchEvent(AWTEvent) dispatchEvent(AWTEvent) method on this EventQueue with the event to be dispatched as an argument.

Characters and Glyphs

The size of the frame includes any area designated for the border.

A Graphics object encapsulates state information needed for the basic rendering operations that Java supports.

Each component managed by a GridBagLayout is associated with an instance of GridBagConstraints .

Instances of this class control the number of copies, default selection, destination, print dialog, file and printer names, page ranges, multiple document handling (including collation), and multi-page imposition (such as duplex) of every print job which uses the instance.

Swing's painting architecture assumes the children of a JComponent do not overlap.

A menu can optionally be a tear-off menu.

The default MenuItem object embodies a simple labeled menu item.

This picture of a menu bar shows five menu items:
The first two items are simple menu items, labeled "Basic" and "Simple". Following these two items is a separator, which is itself a menu item, created with the label "-". Next is an instance of CheckboxMenuItem labeled "Check".

Menu shortcuts are created using virtual keycodes, not characters.

Instances of this class control the color state, paper size (media type), orientation, logical origin, print quality, and resolution of every page which uses the instance.

Instances of this class should be obtained via MouseInfo.getPointerInfo . The PointerInfo instance is not updated dynamically as the mouse moves.

For example, the following image depicts a frame with four text fields of varying widths.