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

Java in a Nutshell

Previous Chapter 20
The java.awt.event Package

20.3 java.awt.event.AdjustmentEvent (JDK 1.1)

An event of this type indicates that an adjustment has been made to an Adjustable object--usually, this means that the user has interacted with a Scrollbar component.

The getValue() method returns the new value of the Adjustable object. This is usually the most important piece of information stored in the event. getAdjustable() returns the Adjustable object that was the source of the event. It is a convenient alternative to the inherited getSource() method.

The getID() method returns the type of an AdjustmentEvent. The standard AWT components only generate adjustment events of type AdjustmentEvent.ADJUSTMENT_VALUE_CHANGED. There are several types of adjustments that can be made to an Adjustable object, however, and the getAdjustmentType() method returns one of five constants to indicate which type has occurred. UNIT_INCREMENT indicates that the Adjustable value has been incremented by one unit, as in a scroll-line-down operation. UNIT_DECREMENT indicates the opposite: scroll-line-up. BLOCK_INCREMENT and BLOCK_DECREMENT indicate that the Adjustable object has been incremented or decremented by multiple units, as in a scroll-page-down or scroll-page-up operation. Finally, the TRACK constant indicates that the Adjustable value has been set to an absolute value unrelated to its previous value, as when the user drags a scrollbar to a new position.

public class AdjustmentEvent extends AWTEvent {
    // Public Constructor
            public AdjustmentEvent(Adjustable source, int id, int type, int value);
    // Constants
            public static final int ADJUSTMENT_FIRST;
            public static final int ADJUSTMENT_LAST;
            public static final int ADJUSTMENT_VALUE_CHANGED;
            public static final int BLOCK_DECREMENT;
            public static final int BLOCK_INCREMENT;
            public static final int TRACK;
            public static final int UNIT_DECREMENT;
            public static final int UNIT_INCREMENT;
    // Public Instance Methods
            public Adjustable getAdjustable();
            public int getAdjustmentType();
            public int getValue();
            public String paramString();  // Overrides AWTEvent



Passed To:

AdjustmentListener.adjustmentValueChanged(), AWTEventMulticaster.adjustmentValueChanged(), Scrollbar.processAdjustmentEvent()

Previous Home Next
java.awt.event.ActionListener (JDK 1.1) Book Index java.awt.event.AdjustmentListener (JDK 1.1)

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