Java Notes

MouseListener

This type of mouse listener is for events which typically don't happen very often -- a mouse button is pressed, released, or the mouse enters or leaves the area of the component with a listener. Here are the actions that a MouseListener catches.

press	one of the mouse buttons is pressed.
release	one of the mouse buttons is released.
click	a mouse button was pressed and released without moving the mouse. This is perhaps the most commonly used.
enter	mouse cursor enters the component. Often used to change cursor.
exit	mouse cursor exits the component. Often used to restore cursor.

To listen for these events you will use addMouseListener.

MouseListener Interface

To implement a MouseListener interface, you must define the following methods. You can copy these definitions into your program and only make a meaningful body for those methods that are of interest.

public void mousePressed(MouseEvent e) {}
public void mouseReleased(MouseEvent e) {}
public void mouseClicked(MouseEvent e) {}
public void mouseEntered(MouseEvent e) {}
public void mouseExited(MouseEvent e) {}

This method is called	When the user does this action
mouseClicked	A click is the result of a press and a release. This is probably the most common method to write.
mousePressed	A mouse button is pressed (any of three possible mouse buttons)
mouseReleased	A mouse button is released.
mouseEntered	The mouse cursor enters a component. You might write this to change the cursor.
mouseExited	The mouse cursor leaves a component. You might write this to restore the cursor.

To Get the Mouse Coordinates

All coordinates are relative to the upper left corner of the component with the mouse listener. Use the following MouseEvent methods to get x and y coordinates of where the mouse event occurred.

• int getX() // returns the x coordinate of the event.
• int getY() // returns the y coordinate of the event.

To Check for Double Clicks

Use the following MouseEvent method to get a count of the number of clicks.

• int getClickCount() // number of mouse clicks