Menu
Both ActionListener and ItemListener are used to fire an event with JCheckBox?
So, what's the difference between them and in which case one of them is preferred to the other?
584
For JButtons, use an Action. For JToggleButtons, JCheckBoxes, and JRadioButtons, use an Action and check its SELECTED_KEY value. If you aren't willing to use Actions, use ActionListener for JButtons, and use ItemListener for JToggleButtons, JCheckBoxes, and JRadioButtons.
The class that is interested in processing an action event implements this interface, and the object created with that class is registered with a component, using the component's addActionListener method. When the action event occurs, that object's actionPerformed method is invoked.
The JCheckBox class is used to create a checkbox. It is used to turn an option on (true) or off (false). Clicking on a CheckBox changes its state from "on" to "off" or from "off" to "on ".
JCheckBox often uses the methods isSelected and setSelected. To select, or un-select, a box, use the setSelected(boolean) method. To check if a box is selected, use the isSelected() method.
Both ItemListener as well as ActionListener, in case of JCheckBox have the same behaviour. However, major difference is ItemListener can be triggered by calling the setSelected(true) on the checkbox. As a coding practice do not register both ItemListener as well as ActionListener with the JCheckBox, in order to avoid inconsistency.
105
The difference is that ActionEvent is fired when the action is performed on the JCheckBox that is its state is changed either by clicking on it with the mouse or with a space bar or a mnemonic. It does not really listen to change events whether the JCheckBox is selected or deselected.
For instance, if JCheckBox c1 (say) is added to a ButtonGroup. Changing the state of other JCheckBoxes in the ButtonGroup will not fire an ActionEvent on other JCheckBox, instead an ItemEvent is fired.
Final words: An ItemEvent is fired even when the user deselects a check box by selecting another JCheckBox (when in a ButtonGroup), however ActionEvent is not generated like that instead ActionEvent only listens whether an action is performed on the JCheckBox (to which the ActionListener is registered only) or not. It does not know about ButtonGroup and all other selection/deselection stuff.
40
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
