What is ActionListener explain with example?
Table of Contents
What is ActionListener explain with example?
You implement an action listener to define what should be done when an user performs certain operation. An action event occurs, whenever an action is performed by the user. Examples: When the user clicks a button, chooses a menu item, presses Enter in a text field.
What is ActionEvent E in Java?
ActionEvent is a class, e is an instance of that class. You can use e to call it’s methods/properties, found here. http://docs.oracle.com/javase/7/docs/api/java/awt/event/ActionEvent.html. ActionEvent is just a type, it informs you what type of object e is. By the way, you can change e to whatever you prefer, for ex.
How does ActionListener work in Java?
To determine where the user clicked on the screen, Java provides an interface called “ActionListener” through which we determine where the user clicked and generates an event to perform several tasks, like calculation, print a value, print a specific character, etcetera using a button.
How do you get the command name for invoking ActionEvent?
Explanation: Action event is generated when a button is pressed, a list item is double-clicked or a menu item is selected. 2. Which of these methods can be used to obtain the command name for invoking ActionEvent object? Explanation: None.
What is ActionEvent class in Java?
public class ActionEvent extends AWTEvent. A semantic event which indicates that a component-defined action occurred. This high-level event is generated by a component (such as a Button ) when the component-specific action occurs (such as being pressed).
What is the use of ActionEvent in Java?
Uses of ActionEvent in java. awt. Handles the actionPerformed event by invoking the actionPerformed methods on listener-a and listener-b. Processes action events occurring on this menu item, by dispatching them to any registered ActionListener objects.
How would you implement ActionListener in another class?
Step 1: Create an event handler class and specify that the class either implements an ActionListener interface or extends a class that implements an ActionListener interface. Step 2: Register an instance of the event handler class as a listener on one or more components.
What is e getSource?
Description. object getSource() Returns the object on which the event occurred. You can use the getSource method to determine which component sourced the event when the listener is registered as an event listener with more than one component.
Which of these events is generated when a button is pressed a WindowEvent B ActionEvent C WindowEvent D KeyEvent?
| Q. | Which of these events is generated when a button is pressed? |
|---|---|
| B. | KeyEvent |
| C. | WindowEvent |
| D. | AdjustmentEvent |
| Answer» a. ActionEvent |
Which method is used to process mouse click in java?
A MouseEvent object is passed to every MouseListener or MouseAdapter object which is registered to receive the “interesting” mouse events using the component’s addMouseListener method. (MouseAdapter objects implement the MouseListener interface.) Each such listener object gets a MouseEvent containing the mouse event.
Why is Jpanel used in swings?
JPanel, a part of the Java Swing package, is a container that can store a group of components. The main task of JPanel is to organize components, various layouts can be set in JPanel which provide better organization of components, however, it does not have a title bar.
