Method Of Key Event Key Listener must implement three methods, keypressed(), keyreleased() & keytyped(). 1) keypressed() : will run whenever a key is

Size: px

Start display at page:

Download "Method Of Key Event Key Listener must implement three methods, keypressed(), keyreleased() & keytyped(). 1) keypressed() : will run whenever a key is"

Lily Jennings
5 years ago
Views:

1 INDEX Event Handling. Key Event. Methods Of Key Event. Example Of Key Event. Mouse Event. Method Of Mouse Event. Mouse Motion Listener. Example of Mouse Event.

2 Event Handling One of the key concept in GUI programming is Event Handling. Some GUI components would register themselves with the Event Source so, the source would tell them when something happens. These are the EventListeners. All Events are objects of Event classes.

3 Key Event Key Event are generated when the user presses or releases keys. For an object to listen for key events, it is necessary to call component.addkeylistener() with the class that implements the inference as the parameter.

4 Method Of Key Event Key Listener must implement three methods, keypressed(), keyreleased() & keytyped(). 1) keypressed() : will run whenever a key is pressed. A key press event is called for every key that is pressed, including keys like Shift &Control. 2) keyreleased() : will run whenever that key is released. 3) keytyped(): combines the two-its runs when the key is pressed & then released & signifies a keystroke.the method keytyped() method reports the actual character typed.

5 Example Of Key Event import java.awt.*; import javax.swing.*; import java.awt.event.*; class keytest extends JFrame public keytest() setsize(400,400); settitle("key Event test"); setdefaultcloseoperation(3); addkeylistener(new KeyHandler()); class KeyHandler implements KeyListener public void keypressed(keyevent e) System.out.println("key is press");

6 public void keyreleased(keyevent e) System.out.println("key is Released"); public void keytyped(keyevent e) System.out.println("key is type"); public static void main(string args[]) keytest t=new keytest(); t.setvisible(true);

7 Mouse Event Mouse Event are generated whenever a mouse moves. There are five methods that are called when MouseEvent occurs ; mouse events are generated when the user presses or releases a mouse button.

8 Methods Of Mouse Events 1)public void mouseentered (MouseEvent e):- The mouseentered () method is called when the mouse first enters the bounding area of the component. 2)public void mouseexited (MouseEvent e):- The mouseexited () method is called when the mouse leaves the bounding area of the component. 3)public void mousepressed (MouseEvent e):- The mousepressed () method is called each time the user presses a mouse button within the component s space. 4)public void mousereleased (MouseEvent e):- This method is called when user releases the mouse button after a mouse press. The user does not have to be over the original component any more ; the original component is the source of the event.

9 5)public void mouseclicked (MouseEvent e):- The mouseclicked () method is called once each time the user clicks a mouse button ; That is, once for each mouse press / mouse release combination. int getx() :-Returns the x position of mouse pointer when the mouse was clicked. int gety() :-Returns the y position of mouse pointer when the mouse was clicked. int getclickcount():- Returns the number of consecutive mouse clicks associated with this event. To distinguish between single & double clicks use the getclickcount() method.

10 Mouse Motion Listener The mouse move & drag events are defined in a separate interface called MouseMotionListener. The MouseMotionListener interface contains two methods that are called when a MouseEvent occurs ; mouse motion events are generated when the user moves the mouse, whether or not a button is pressed.

11 Method of MouseMotionListener:- 1)public void mousemoved(mouseevent e):- This method is called every time the mouse moves within the bounding areas of the components & no mouse button is pressed. 2)public void mousedragged (MouseEvent e):- This method is called every time the mouse moves while a mouse button is pressed.

12 Example Of Mouse Event import java.awt.event.*; import javax.swing.*; public class MouseEventTest1 extends JFrame public MouseEventTest1() setsize(400,300); settitle("methods of Mouse Event"); setdefaultcloseoperation(3); addmouselistener(new MouseHandler()); class MouseHandler extends MouseAdapter public void mousepressed(mouseevent e) System.out.println("Mouse Pressed");

13 public void mousereleased(mouseevent e) System.out.println("Mouse Released"); public void mouseentered(mouseevent e) System.out.println("Mouse Entered"); public void mouseexited(mouseevent e) System.out.println("Mouse Exited"); public void mouseclicked(mouseevent e) System.out.println("Mouse Clicked"); public static void main(string args[]) new MouseEventTest1().setVisible(true);

Graphical User Interfaces 2

Graphical User Interfaces 2 CSCI 136: Fundamentals CSCI 136: Fundamentals of Computer of Science Computer II Science Keith II Vertanen Keith Vertanen Copyright 2011 Extending JFrame Dialog boxes Overview