1. Write a prolog program to calculate the sum of two numbers.
sum(X,Y):-S is X+Y,write(S).
OUTPUT:
1. Write a prolog program to calculate the sum of two numbers.
sum(X,Y):-S is X+Y,write(S).
OUTPUT:
The AWT classes are contained in the java.awt package. It is one of Java’s largest packages. Fortunately, because it is logically organized in a top-down, hierarchical fashion.
Event Listener Interfaces
event model has two parts: sources and listeners.
Listeners are created by implementing one or more of the interfaces defined by the java.awt.event package. When an event occurs, the event source invokes the appropriate method defined by the listener and provides an event object as its argument.
The TextEvent Class Instances of this class describe text events. These are generated by text fields and text areas when characters are entered by a user or program. TextEvent defines the integer constant TEXT_VALUE_CHANGED.
The one constructor for this class is shown here: TextEvent(Object src, int type) Here, src is a reference to the object that generated this event. The type of the event is specified by type.
Here, src is a reference to the component that generated the event. The system time at which the mouse event occurred is passed in when.
The modifiers argument indicates which modifiers were pressed when a mouse event occurred. The coordinates of the mouse are passed in x and y. The click count is passed in clicks.
The triggersPopup flag indicates if this event causes a pop-up menu to appear on this platform.
Two commonly used methods in this class are getX( ) and getY( ).
These return the X and Y coordinates of the mouse within the component when the event occurred.
Point getPoint( ) It returns a Point object that contains the X,Y coordinates in its integer members: x and y.
The translatePoint( ) method changes the location of the event. Its form is shown here: void translatePoint(int x, int y) Here, the arguments x and y are added to the coordinates of the event.
The getClickCount( ) method obtains the number of mouse clicks for this event. Its signature is shown here: int getClickCount( )
The isPopupTrigger( ) method tests if this event causes a pop-up menu to appear on this platform. Its form is shown here: boolean isPopupTrigger( )
int getButton( ) It returns a value that represents the button that caused the event. The return value will be one of these constants defined by MouseEvent:
NOBUTTON
BUTTON1
BUTTON2
BUTTON3
The NOBUTTON value indicates that no button was pressed or released. Java SE 6 added three methods to MouseEvent that obtain the coordinates of the mouse relative to the screen rather than the component.
They are shown here:
Point getLocationOnScreen( )
int getXOnScreen( )
int getYOnScreen( )
The getLocationOnScreen( ) method returns a Point object that contains both the X and Y coordinate. The other two methods return the indicated coordinate
Event Class | Description |
---|---|
ActionEvent | Generated when a button is pressed, a list item is double-clicked, or a menu item is selected. |
AdjustmentEvent | Generated when a scroll bar is manipulated. |
ComponentEvent | Generated when a component is hidden, moved, resized, or becomes visible. |
ContainerEvent | Generated when a component is added to or removed from a container. |
FocusEvent | Generated when a component gains or loses keyboard focus. |
InputEvent | Abstract superclass for all component input event classes. |
ItemEvent | Generated when a check box or list item is clicked; also occurs when a choice selection is made or a checkable menu item is selected or deselected. |
KeyEvent | Generated when input is received from the keyboard. |
MouseEvent | Generated when the mouse is dragged, moved, clicked, pressed, or released; also generated when the mouse enters or exits a component. |
MouseWheelEvent | Generated when the mouse wheel is moved |
TextEvent | Generated when the value of a text area or text field is changed. |
WindowEvent | Generated when a window is activated, closed, deactivated, deiconified, iconified, opened, or quit. |