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Class MouseEvent

All Implemented Interfaces:
Serializable
Direct Known Subclasses:
MenuDragMouseEvent, MouseWheelEvent 
public class MouseEvent
extends InputEvent

An event which indicates that a mouse action occurred in a component. A mouse action is considered to occur in a particular component if and only if the mouse cursor is over the unobscured part of the component's bounds when the action happens. For lightweight components, such as Swing's components, mouse events are only dispatched to the component if the mouse event type has been enabled on the component. A mouse event type is enabled by adding the appropriate mouse-based EventListener to the component (MouseListener or MouseMotionListener), or by invoking Component.enableEvents(long) with the appropriate mask parameter (AWTEvent.MOUSE_EVENT_MASK or AWTEvent.MOUSE_MOTION_EVENT_MASK). If the mouse event type has not been enabled on the component, the corresponding mouse events are dispatched to the first ancestor that has enabled the mouse event type.

For example, if a MouseListener has been added to a component, or enableEvents(AWTEvent.MOUSE_EVENT_MASK) has been invoked, then all the events defined by MouseListener are dispatched to the component. On the other hand, if a MouseMotionListener has not been added and enableEvents has not been invoked with AWTEvent.MOUSE_MOTION_EVENT_MASK, then mouse motion events are not dispatched to the component. Instead the mouse motion events are dispatched to the first ancestors that has enabled mouse motion events.

This low-level event is generated by a component object for:

  • Mouse Events
    • a mouse button is pressed
    • a mouse button is released
    • a mouse button is clicked (pressed and released)
    • the mouse cursor enters the unobscured part of component's geometry
    • the mouse cursor exits the unobscured part of component's geometry
  • Mouse Motion Events
    • the mouse is moved
    • the mouse is dragged

A MouseEvent object is passed to every MouseListener or MouseAdapter object which is registered to receive the "interesting" mouse events using the component's addMouseListener method. (MouseAdapter objects implement the MouseListener interface.) Each such listener object gets a MouseEvent containing the mouse event.

A MouseEvent object is also passed to every MouseMotionListener or MouseMotionAdapter object which is registered to receive mouse motion events using the component's addMouseMotionListener method. (MouseMotionAdapter objects implement the MouseMotionListener interface.) Each such listener object gets a MouseEvent containing the mouse motion event.

When a mouse button is clicked, events are generated and sent to the registered MouseListeners. The state of modal keys can be retrieved using InputEvent.getModifiers() and InputEvent.getModifiersEx(). The button mask returned by InputEvent.getModifiers() reflects only the button that changed state, not the current state of all buttons. (Note: Due to overlap in the values of ALT_MASK/BUTTON2_MASK and META_MASK/BUTTON3_MASK, this is not always true for mouse events involving modifier keys). To get the state of all buttons and modifier keys, use InputEvent.getModifiersEx(). The button which has changed state is returned by getButton()

For example, if the first mouse button is pressed, events are sent in the following order: 

id              modifiers    button 
    MOUSE_PRESSED:  BUTTON1_MASK BUTTON1
    MOUSE_RELEASED: BUTTON1_MASK BUTTON1
    MOUSE_CLICKED:  BUTTON1_MASK BUTTON1
When multiple mouse buttons are pressed, each press, release, and click results in a separate event.

For example, if the user presses button 1 followed by button 2, and then releases them in the same order, the following sequence of events is generated: 

id              modifiers    button 
    MOUSE_PRESSED:  BUTTON1_MASK BUTTON1
    MOUSE_PRESSED:  BUTTON2_MASK BUTTON2
    MOUSE_RELEASED: BUTTON1_MASK BUTTON1
    MOUSE_CLICKED:  BUTTON1_MASK BUTTON1
    MOUSE_RELEASED: BUTTON2_MASK BUTTON2
    MOUSE_CLICKED:  BUTTON2_MASK BUTTON2
If button 2 is released first, the MOUSE_RELEASED/MOUSE_CLICKED pair for BUTTON2_MASK arrives first, followed by the pair for BUTTON1_MASK.

Some extra mouse buttons are added to extend the standard set of buttons represented by the following constants:BUTTON1, BUTTON2, and BUTTON3. Extra buttons have no assigned BUTTONx constants as well as their button masks have no assigned BUTTONx_DOWN_MASK constants. Nevertheless, ordinal numbers starting from 4 may be used as button numbers (button ids). Values obtained by the getMaskForButton(button) method may be used as button masks.

MOUSE_DRAGGED events are delivered to the Component in which the mouse button was pressed until the mouse button is released (regardless of whether the mouse position is within the bounds of the Component). Due to platform-dependent Drag&Drop implementations, MOUSE_DRAGGED events may not be delivered during a native Drag&Drop operation. In a multi-screen environment mouse drag events are delivered to the Component even if the mouse position is outside the bounds of the GraphicsConfiguration associated with that Component. However, the reported position for mouse drag events in this case may differ from the actual mouse position:

  • In a multi-screen environment without a virtual device:
    The reported coordinates for mouse drag events are clipped to fit within the bounds of the GraphicsConfiguration associated with the Component.
  • In a multi-screen environment with a virtual device:
    The reported coordinates for mouse drag events are clipped to fit within the bounds of the virtual device associated with the Component.

An unspecified behavior will be caused if the id parameter of any particular MouseEvent instance is not in the range from MOUSE_FIRST to MOUSE_LAST-1 (MOUSE_WHEEL is not acceptable).

Since:
1.1
See Also:
MouseAdapter, MouseListener, MouseMotionAdapter, MouseMotionListener, MouseWheelListener, Tutorial: Writing a Mouse Listener, Tutorial: Writing a Mouse Motion Listener, Serialized Form

Fields

MOUSE_FIRST

public static final int MOUSE_FIRST

The first number in the range of ids used for mouse events.

MOUSE_LAST

public static final int MOUSE_LAST

The last number in the range of ids used for mouse events.

MOUSE_CLICKED

public static final int MOUSE_CLICKED

The "mouse clicked" event. This MouseEvent occurs when a mouse button is pressed and released.

MOUSE_PRESSED

public static final int MOUSE_PRESSED

The "mouse pressed" event. This MouseEvent occurs when a mouse button is pushed down.

MOUSE_RELEASED

public static final int MOUSE_RELEASED

The "mouse released" event. This MouseEvent occurs when a mouse button is let up.

MOUSE_MOVED

public static final int MOUSE_MOVED

The "mouse moved" event. This MouseEvent occurs when the mouse position changes.

MOUSE_ENTERED

public static final int MOUSE_ENTERED

The "mouse entered" event. This MouseEvent occurs when the mouse cursor enters the unobscured part of component's geometry.

MOUSE_EXITED

public static final int MOUSE_EXITED

The "mouse exited" event. This MouseEvent occurs when the mouse cursor exits the unobscured part of component's geometry.

MOUSE_DRAGGED

public static final int MOUSE_DRAGGED

The "mouse dragged" event. This MouseEvent occurs when the mouse position changes while a mouse button is pressed.

MOUSE_WHEEL

public static final int MOUSE_WHEEL

The "mouse wheel" event. This is the only MouseWheelEvent. It occurs when a mouse equipped with a wheel has its wheel rotated.

Since:
1.4

NOBUTTON

public static final int NOBUTTON

Indicates no mouse buttons; used by getButton().

Since:
1.4

BUTTON1

public static final int BUTTON1

Indicates mouse button #1; used by getButton().

Since:
1.4

BUTTON2

public static final int BUTTON2

Indicates mouse button #2; used by getButton().

Since:
1.4

BUTTON3

public static final int BUTTON3

Indicates mouse button #3; used by getButton().

Since:
1.4

Constructors

MouseEvent

public MouseEvent(Component source,
                  int id,
                  long when,
                  int modifiers,
                  int x,
                  int y,
                  int clickCount,
                  boolean popupTrigger,
                  int button)

Constructs a MouseEvent object with the specified source component, type, time, modifiers, coordinates, click count, popupTrigger flag, and button number.

Creating an invalid event (such as by using more than one of the old _MASKs, or modifier/button values which don't match) results in unspecified behavior. An invocation of the form MouseEvent(source, id, when, modifiers, x, y, clickCount, popupTrigger, button) behaves in exactly the same way as the invocation MouseEvent(source, id, when, modifiers, x, y, xAbs, yAbs, clickCount, popupTrigger, button) where xAbs and yAbs defines as source's location on screen plus relative coordinates x and y. xAbs and yAbs are set to zero if the source is not showing. This method throws an IllegalArgumentException if source is null.

Parameters:
source - The Component that originated the event
id - An integer indicating the type of event. For information on allowable values, see the class description for MouseEvent
when - A long integer that gives the time the event occurred. Passing negative or zero value is not recommended
modifiers - a modifier mask describing the modifier keys and mouse buttons (for example, shift, ctrl, alt, and meta) that are down during the event. Only extended modifiers are allowed to be used as a value for this parameter (see the InputEvent.getModifiersEx() class for the description of extended modifiers). Passing negative parameter is not recommended. Zero value means that no modifiers were passed
x - The horizontal x coordinate for the mouse location. It is allowed to pass negative values
y - The vertical y coordinate for the mouse location. It is allowed to pass negative values
clickCount - The number of mouse clicks associated with event. Passing negative value is not recommended
popupTrigger - A boolean that equals true if this event is a trigger for a popup menu
button - An integer that indicates, which of the mouse buttons has changed its state. The following rules are applied to this parameter:
  • If support for the extended mouse buttons is disabled by Java then it is allowed to create MouseEvent objects only with the standard buttons: NOBUTTON, BUTTON1, BUTTON2, and BUTTON3.
  • If support for the extended mouse buttons is enabled by Java then it is allowed to create MouseEvent objects with the standard buttons. In case the support for extended mouse buttons is enabled by Java, then in addition to the standard buttons, MouseEvent objects can be created using buttons from the range starting from 4 to MouseInfo.getNumberOfButtons() if the mouse has more than three buttons.
Throws:
IllegalArgumentException - if button is less then zero
IllegalArgumentException - if source is null
IllegalArgumentException - if button is greater then BUTTON3 and the support for extended mouse buttons is disabled by Java
IllegalArgumentException - if button is greater then the current number of buttons and the support for extended mouse buttons is enabled by Java
IllegalArgumentException - if an invalid button value is passed in
IllegalArgumentException - if source is null
Since:
1.4
See Also:
EventObject.getSource(), AWTEvent.getID(), InputEvent.getWhen(), InputEvent.getModifiers(), getX(), getY(), getClickCount(), isPopupTrigger(), getButton()

MouseEvent

public MouseEvent(Component source,
                  int id,
                  long when,
                  int modifiers,
                  int x,
                  int y,
                  int clickCount,
                  boolean popupTrigger)

Constructs a MouseEvent object with the specified source component, type, modifiers, coordinates, click count, and popupTrigger flag. An invocation of the form MouseEvent(source, id, when, modifiers, x, y, clickCount, popupTrigger) behaves in exactly the same way as the invocation MouseEvent(source, id, when, modifiers, x, y, xAbs, yAbs, clickCount, popupTrigger, MouseEvent.NOBUTTON) where xAbs and yAbs defines as source's location on screen plus relative coordinates x and y. xAbs and yAbs are set to zero if the source is not showing. This method throws an IllegalArgumentException if source is null.

Parameters:
source - The Component that originated the event
id - An integer indicating the type of event. For information on allowable values, see the class description for MouseEvent
when - A long integer that gives the time the event occurred. Passing negative or zero value is not recommended
modifiers - a modifier mask describing the modifier keys and mouse buttons (for example, shift, ctrl, alt, and meta) that are down during the event. Only extended modifiers are allowed to be used as a value for this parameter (see the InputEvent.getModifiersEx() class for the description of extended modifiers). Passing negative parameter is not recommended. Zero value means that no modifiers were passed
x - The horizontal x coordinate for the mouse location. It is allowed to pass negative values
y - The vertical y coordinate for the mouse location. It is allowed to pass negative values
clickCount - The number of mouse clicks associated with event. Passing negative value is not recommended
popupTrigger - A boolean that equals true if this event is a trigger for a popup menu
Throws:
IllegalArgumentException - if source is null
See Also:
EventObject.getSource(), AWTEvent.getID(), InputEvent.getWhen(), InputEvent.getModifiers(), getX(), getY(), getClickCount(), isPopupTrigger()

MouseEvent

public MouseEvent(Component source,
                  int id,
                  long when,
                  int modifiers,
                  int x,
                  int y,
                  int xAbs,
                  int yAbs,
                  int clickCount,
                  boolean popupTrigger,
                  int button)

Constructs a MouseEvent object with the specified source component, type, time, modifiers, coordinates, absolute coordinates, click count, popupTrigger flag, and button number.

Creating an invalid event (such as by using more than one of the old _MASKs, or modifier/button values which don't match) results in unspecified behavior. Even if inconsistent values for relative and absolute coordinates are passed to the constructor, the mouse event instance is still created and no exception is thrown. This method throws an IllegalArgumentException if source is null.

Parameters:
source - The Component that originated the event
id - An integer indicating the type of event. For information on allowable values, see the class description for MouseEvent
when - A long integer that gives the time the event occurred. Passing negative or zero value is not recommended
modifiers - a modifier mask describing the modifier keys and mouse buttons (for example, shift, ctrl, alt, and meta) that are down during the event. Only extended modifiers are allowed to be used as a value for this parameter (see the InputEvent.getModifiersEx() class for the description of extended modifiers). Passing negative parameter is not recommended. Zero value means that no modifiers were passed
x - The horizontal x coordinate for the mouse location. It is allowed to pass negative values
y - The vertical y coordinate for the mouse location. It is allowed to pass negative values
xAbs - The absolute horizontal x coordinate for the mouse location It is allowed to pass negative values
yAbs - The absolute vertical y coordinate for the mouse location It is allowed to pass negative values
clickCount - The number of mouse clicks associated with event. Passing negative value is not recommended
popupTrigger - A boolean that equals true if this event is a trigger for a popup menu
button - An integer that indicates, which of the mouse buttons has changed its state. The following rules are applied to this parameter:
  • If support for the extended mouse buttons is disabled by Java then it is allowed to create MouseEvent objects only with the standard buttons: NOBUTTON, BUTTON1, BUTTON2, and BUTTON3.
  • If support for the extended mouse buttons is enabled by Java then it is allowed to create MouseEvent objects with the standard buttons. In case the support for extended mouse buttons is enabled by Java, then in addition to the standard buttons, MouseEvent objects can be created using buttons from the range starting from 4 to MouseInfo.getNumberOfButtons() if the mouse has more than three buttons.
Throws:
IllegalArgumentException - if button is less then zero
IllegalArgumentException - if source is null
IllegalArgumentException - if button is greater then BUTTON3 and the support for extended mouse buttons is disabled by Java
IllegalArgumentException - if button is greater then the current number of buttons and the support for extended mouse buttons is enabled by Java
IllegalArgumentException - if an invalid button value is passed in
IllegalArgumentException - if source is null
Since:
1.6
See Also:
EventObject.getSource(), AWTEvent.getID(), InputEvent.getWhen(), InputEvent.getModifiers(), getX(), getY(), getXOnScreen(), getYOnScreen(), getClickCount(), isPopupTrigger(), getButton(), button, Toolkit.areExtraMouseButtonsEnabled(), MouseInfo.getNumberOfButtons(), InputEvent.getMaskForButton(int)

Methods

getLocationOnScreen

public Point getLocationOnScreen()

Returns the absolute x, y position of the event. In a virtual device multi-screen environment in which the desktop area could span multiple physical screen devices, these coordinates are relative to the virtual coordinate system. Otherwise, these coordinates are relative to the coordinate system associated with the Component's GraphicsConfiguration.

Returns:
a Point object containing the absolute x and y coordinates.
Since:
1.6
See Also:
GraphicsConfiguration

getXOnScreen

public int getXOnScreen()

Returns the absolute horizontal x position of the event. In a virtual device multi-screen environment in which the desktop area could span multiple physical screen devices, this coordinate is relative to the virtual coordinate system. Otherwise, this coordinate is relative to the coordinate system associated with the Component's GraphicsConfiguration.

Returns:
x an integer indicating absolute horizontal position.
Since:
1.6
See Also:
GraphicsConfiguration

getYOnScreen

public int getYOnScreen()

Returns the absolute vertical y position of the event. In a virtual device multi-screen environment in which the desktop area could span multiple physical screen devices, this coordinate is relative to the virtual coordinate system. Otherwise, this coordinate is relative to the coordinate system associated with the Component's GraphicsConfiguration.

Returns:
y an integer indicating absolute vertical position.
Since:
1.6
See Also:
GraphicsConfiguration

getModifiersEx

public int getModifiersEx()

Returns the extended modifier mask for this event.

Extended modifiers are the modifiers that ends with the _DOWN_MASK suffix, such as ALT_DOWN_MASK, BUTTON1_DOWN_MASK, and others.

Extended modifiers represent the state of all modal keys, such as ALT, CTRL, META, and the mouse buttons just after the event occurred.

For example, if the user presses button 1 followed by button 2, and then releases them in the same order, the following sequence of events is generated: 

MOUSE_PRESSED:  BUTTON1_DOWN_MASK
    MOUSE_PRESSED:  BUTTON1_DOWN_MASK | BUTTON2_DOWN_MASK
    MOUSE_RELEASED: BUTTON2_DOWN_MASK
    MOUSE_CLICKED:  BUTTON2_DOWN_MASK
    MOUSE_RELEASED:
    MOUSE_CLICKED:

It is not recommended to compare the return value of this method using == because new modifiers can be added in the future. For example, the appropriate way to check that SHIFT and BUTTON1 are down, but CTRL is up is demonstrated by the following code: 

int onmask = SHIFT_DOWN_MASK | BUTTON1_DOWN_MASK;
    int offmask = CTRL_DOWN_MASK;
    if ((event.getModifiersEx() & (onmask | offmask)) == onmask) {
        ...
    }
The above code will work even if new modifiers are added.
Overrides:
getModifiersEx in class InputEvent

getX

public int getX()

Returns the horizontal x position of the event relative to the source component.

Returns:
x an integer indicating horizontal position relative to the component

getY

public int getY()

Returns the vertical y position of the event relative to the source component.

Returns:
y an integer indicating vertical position relative to the component

getPoint

public Point getPoint()

Returns the x,y position of the event relative to the source component.

Returns:
a Point object containing the x and y coordinates relative to the source component

translatePoint

public void translatePoint(int x,
                           int y)

Translates the event's coordinates to a new position by adding specified x (horizontal) and y (vertical) offsets.

Parameters:
x - the horizontal x value to add to the current x coordinate position
y - the vertical y value to add to the current y coordinate position

getClickCount

public int getClickCount()

Returns the number of mouse clicks associated with this event.

Returns:
integer value for the number of clicks

getButton

public int getButton()

Returns which, if any, of the mouse buttons has changed state. The returned value is ranged from 0 to the MouseInfo.getNumberOfButtons() value. The returned value includes at least the following constants:

  • NOBUTTON
  • BUTTON1
  • BUTTON2
  • BUTTON3
It is allowed to use those constants to compare with the returned button number in the application. For example, 
if (anEvent.getButton() == MouseEvent.BUTTON1) {
In particular, for a mouse with one, two, or three buttons this method may return the following values:
  • 0 (NOBUTTON)
  • 1 (BUTTON1)
  • 2 (BUTTON2)
  • 3 (BUTTON3)
Button numbers greater then BUTTON3 have no constant identifier. So if a mouse with five buttons is installed, this method may return the following values:
  • 0 (NOBUTTON)
  • 1 (BUTTON1)
  • 2 (BUTTON2)
  • 3 (BUTTON3)
  • 4
  • 5

Note: If support for extended mouse buttons is disabled by Java then the AWT event subsystem does not produce mouse events for the extended mouse buttons. So it is not expected that this method returns anything except NOBUTTON, BUTTON1, BUTTON2, BUTTON3.

Returns:
one of the values from 0 to MouseInfo.getNumberOfButtons() if support for the extended mouse buttons is enabled by Java. That range includes NOBUTTON, BUTTON1, BUTTON2, BUTTON3;
NOBUTTON, BUTTON1, BUTTON2 or BUTTON3 if support for the extended mouse buttons is disabled by Java
Since:
1.4
See Also:
Toolkit.areExtraMouseButtonsEnabled(), MouseInfo.getNumberOfButtons(), MouseEvent(Component, int, long, int, int, int, int, int, int, boolean, int), InputEvent.getMaskForButton(int)

isPopupTrigger

public boolean isPopupTrigger()

Returns whether or not this mouse event is the popup menu trigger event for the platform.

Note: Popup menus are triggered differently on different systems. Therefore, isPopupTrigger should be checked in both mousePressed and mouseReleased for proper cross-platform functionality.

Returns:
boolean, true if this event is the popup menu trigger for this platform

getMouseModifiersText

public static String getMouseModifiersText(int modifiers)

Returns a String instance describing the modifier keys and mouse buttons that were down during the event, such as "Shift", or "Ctrl+Shift". These strings can be localized by changing the awt.properties file.

Note that the InputEvent.ALT_MASK and InputEvent.BUTTON2_MASK have equal values, so the "Alt" string is returned for both modifiers. Likewise, the InputEvent.META_MASK and InputEvent.BUTTON3_MASK have equal values, so the "Meta" string is returned for both modifiers.

Note that passing negative parameter is incorrect, and will cause the returning an unspecified string. Zero parameter means that no modifiers were passed and will cause the returning an empty string.

Parameters:
modifiers - A modifier mask describing the modifier keys and mouse buttons that were down during the event
Returns:
string string text description of the combination of modifier keys and mouse buttons that were down during the event
Since:
1.4
See Also:
InputEvent.getModifiersExText(int)

paramString

public String paramString()

Returns a parameter string identifying this event. This method is useful for event-logging and for debugging.

Overrides:
paramString in class ComponentEvent
Returns:
a string identifying the event and its attributes

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