Explain Interface In Java,The AdjustmentListener Interface, The WindowListener Interface, The FocusListener Interface Explain
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The AdjustmentListener Interface
This interface defines the
adjustmentValueChanged( )
method that is invoked when an
adjustment event occurs. Its general form is shown here:
void adjustmentValueChanged(AdjustmentEvent ae )
The ComponentListener Interface
This interface defines four methods that are invoked when a component is resized, moved,
shown, or hidden. Their general forms are shown here:
void componentResized(ComponentEvent ce )
void componentMoved(ComponentEvent ce )
void componentShown(ComponentEvent ce )
void componentHidden(ComponentEvent ce )
The ContainerListener Interface
This interface contains two methods. When a component is added to a container,
componentAdded( )
is invoked. When a component is removed from a container,
componentRemoved( )
is invoked. Their general forms are shown here:
void componentAdded(ContainerEvent ce )
void componentRemoved(ContainerEvent ce )
The FocusListener Interface
This interface defines two methods. When a component obtains keyboard focus,
focusGained( )
is invoked. When a component loses keyboard focus,
focusLost( )
is called. Their general
forms are shown here:
void focusGained(FocusEvent fe )
void focusLost(FocusEvent fe )
The ItemListener Interface
This interface defines the
itemStateChanged( )
method that is invoked when the state of an
item changes. Its general form is shown here:
void itemStateChanged(ItemEvent ie )
The KeyListener Interface
This interface defines three methods. The
keyPressed( )
and
keyReleased( )
methods are
invoked when a key is pressed and released, respectively. The
keyTyped( )
method is invoked
when a character has been entered.
For example, if a user presses and releases the A key, three events are generated in sequence:
key pressed, typed, and released. If a user presses and releases the HOME key, two key events
are generated in sequence: key pressed and released.
The general forms of these methods are shown here:
void keyPressed(KeyEvent ke )
void keyReleased(KeyEvent ke )
void keyTyped(KeyEvent ke )
The MouseListener Interface
This interface defines five methods. If the mouse is pressed and released at the same point,
mouseClicked( )
is invoked. When the mouse enters a component, the
mouseEntered( )
method is called. When it leaves,
mouseExited( )
is called. The
mousePressed( )
and
mouseReleased( )
methods are invoked when the mouse is pressed and released, respectively.
The general forms of these methods are shown here:
void mouseClicked(MouseEvent me )
void mouseEntered(MouseEvent me )
void mouseExited(MouseEvent me )
void mousePressed(MouseEvent me )
void mouseReleased(MouseEvent me )
The MouseMotionListener Interface
This interface defines two methods. The
mouseDragged( )
method is called multiple times
as the mouse is dragged. The
mouseMoved( )
method is called multiple times as the mouse
is moved. Their general forms are shown here:
void mouseDragged(MouseEvent me )
void mouseMoved(MouseEvent me )
The MouseWheelListener Interface
This interface defines the
mouseWheelMoved( )
method that is invoked when the mouse
wheel is moved. Its general form is shown here:
void mouseWheelMoved(MouseWheelEvent mwe )
The TextListener Interface
This interface defines the
textChanged( )
method that is invoked when a change occurs
in a text area or text field. Its general form is shown here:
void textChanged(TextEvent te )
The WindowFocusListener Interface
This interface defines two methods:
windowGainedFocus( )
and
windowLostFocus( )
.
These
are called when a window gains or loses input focus. Their general forms are shown here:
void windowGainedFocus(WindowEvent we )
void windowLostFocus(WindowEvent we )
The WindowListener Interface
This interface defines seven methods. The
windowActivated( )
and
windowDeactivated( )
methods are invoked when a window is activated or deactivated, respectively. If a window
is iconified, the
windowIconified( )
method is called. When a window is deiconified,
the
windowDeiconified( )
method is called. When a window is opened or closed, the
windowOpened( )
or
windowClosed( )
methods are called, respectively. The
windowClosing( )
method is called when a window is being closed. The general forms of these methods are
void windowActivated(WindowEvent we )
void windowClosed(WindowEvent we )
void windowClosing(WindowEvent we )
void windowDeactivated(WindowEvent we )
void windowDeiconified(WindowEvent we )
void windowIconified(WindowEvent we )
void windowOpened(WindowEvent we )