Java Reference
In-Depth Information
ods are called when the mouse interacts with a
Component
if appropriate event-listener ob-
jects are registered for that
Component
.
Each of the mouse event-handling methods receives as an argument a
MouseEvent
object that contains information about the mouse event that occurred, including the
x-
and
y
-coordinates of its location. These coordinates are measured from the
upper-left corner
of the GUI component on which the event occurred. The
x
-coordinates start at 0 and
increase from left to right
. The
y
-coordinates start at 0 and
increase from top to bottom
. The
methods and constants of class
InputEvent
(
MouseEvent
's superclass) enable you to deter-
mine which mouse button the user clicked.
MouseListener
and
MouseMotionListener
interface methods
Methods of interface
MouseListener
public void mousePressed(MouseEvent event)
Called when a mouse button is
pressed
while the mouse cursor is on a component.
public void mouseClicked(MouseEvent event)
Called when a mouse button is
pressed and released
while the mouse cursor remains sta-
tionary on a component. Always preceded by a call to
mousePressed
and
mouseReleased
.
public void mouseReleased(MouseEvent event)
Called when a mouse button is
released after being pressed
. Always preceded by a call to
mousePressed
and one or more calls to
mouseDragged
.
public void mouseEntered(MouseEvent event)
Called when the mouse cursor
enters
the bounds of a component.
public void mouseExited(MouseEvent event)
Called when the mouse cursor
leaves
the bounds of a component.
Methods of interface
MouseMotionListener
public void mouseDragged(MouseEvent event)
Called when the mouse button is
pressed
while the mouse cursor is on a component and
the mouse is
moved
while the mouse button
remains pressed
. Always preceded by a call to
mousePressed
. All drag events are sent to the component on which the user began to drag
the mouse.
public void mouseMoved(MouseEvent event)
Called when the mouse is
moved
(with no mouse buttons pressed) when the mouse cursor
is on a component. All move events are sent to the component over which the mouse is
currently positioned.
Fig. 12.27
|
MouseListener
and
MouseMotionListener
interface methods.
Software Engineering Observation 12.5
Calls to
mouseDragged
are sent to the
MouseMotionListener
for the
Component
on which
the drag started. Similarly, the
mouseReleased
call at the end of a drag operation is sent
to the
MouseListener
for the
Component
on which the drag operation started.
