1. Write a prolog program to calculate the sum of two numbers.

1. Write a prolog program to calculate the sum of two numbers. 

sum(X,Y):-S is X+Y,write(S).

OUTPUT:

Container class

 

AWT Classes

 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 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. 

Sources of Events

 

The TextEvent Class

 

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.

The MouseEvent Class

 

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

The ComponentEvent Class

 

The AdjustmentEvent Class

Main Event Classes in java.awt.event

 

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.