home | O'Reilly's CD bookshelfs | FreeBSD | Linux | Cisco | Cisco Exam  

Java in a Nutshell

Previous Chapter 18
The java.awt Package

18.21 java.awt.EventQueue (JDK 1.1)

This class implements an event queue for AWT events in Java 1.1. When an EventQueue is created, a new thread is automatically created and started to remove events from the front of the queue and dispatch them to the appropriate component. It is this thread, created by the EventQueue, that notifies event listeners and executes most of the code in a typical GUI-driven application.

An application can create and use its own private EventQueue, but all AWT events are placed on and dispatched from a single system EventQueue. Use the getSystemEventQueue() method of the Toolkit class to get the system EventQueue object.

getNextEvent() removes and returns the event at the front of the queue. It blocks if there are no events in the queue. peekEvent() returns the event at the front of the queue without removing it from the queue. Passed an optional AWTEvent id field, it returns the first event of the specified type. Finally, postEvent() places a new event on the end of the event queue.

Most applications do not need to use the EventQueue class at all; they can simply rely on the system to dispatch events automatically.

public class EventQueue extends Object {
    // Public Constructor
            public EventQueue();
    // Public Instance Methods
            public synchronized AWTEvent getNextEvent() throws InterruptedException;
            public synchronized AWTEvent peekEvent();
            public synchronized AWTEvent peekEvent(int id);
            public synchronized void postEvent(AWTEvent theEvent);

Returned By:

Toolkit.getSystemEventQueue(), Toolkit.getSystemEventQueueImpl()

Previous Home Next
java.awt.Event (JDK 1.0) Book Index java.awt.FileDialog (JDK 1.0)

Java in a Nutshell Java Language Reference Java AWT Java Fundamental Classes Exploring Java