July 28, by geekycoder. For those who been using Swing to develop Desktop Application will undoubtedly find that it is one of the most flexible and API-rich toolkit available. However such power comes at a price of complexity due to many ways of accomplishing the same task. This post will talk about the common listeners that often confused both beginners and veteran alike. Many thought that they are synonymous and interchangeable, and indeed the lack of understanding is often the source of confusion not only for those beginners in using Swing but also experienced Swing developer.
The inappropiate use of ActionListener and ItemListener are often one of the common source of hard-to-find bugs. Take for example of JCheckBox. In a way, both listeners for JCheckBox work similarly in that both will fire event upon change in state, whether by clicking or toggle by spacebar or programmatically through doClick method Similar to mouse click.
So why is it important? Consider when application startup, the GUI needed to configure for defined state, and using setSelected will trigger ItemListener. Do not register both ActionListener and ItemListener as both will be fired, landing the component in a random state Note the listener event model does not guarantee the sequence of event trigger.
Similarly, JComboBox behaves differently for these two types of Listener. Read more at. ActionEvent; import java. ActionListener; import java. ItemEvent; import java. Posted in Programming 5 Comments. I believe you have an error in your program. Otherwise I found this example very helpful, thank you! Comments RSS. You are commenting using your WordPress.
You are commenting using your Google account. You are commenting using your Twitter account. You are commenting using your Facebook account. Notify me of new comments via email.Posted by: admin December 21, Leave a comment. However, major difference is ItemListener can be triggered by calling the setSelected true on the checkbox. It does not really listen to change events whether the JCheckBox is selected or deselected.
Final words: An ItemEvent is fired even when the user deselects a check box by selecting another JCheckBox when in a ButtonGrouphowever 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. Together with if event. I experimented myself in order to get a good answer code below.
The ONLY difference I can tell between these two listeners is the type of Event Object that gets returned with the listener is different. The return types of an ActionEvent and an ItemEvent will have different methods stored that may be used when an Event Type gets fired. In the code below the comments show the difference in. Then I wrote the Listener classes below with ActionListener fully commented because I tested it first in this experiment.
You will notice that if you add this panel to a frame and display, all radiobuttons and checkboxes always fire regardless of the Listener type, just comment out the methods in one and try the other and vice versa.
Both Listeners fire events the same way. Explained a little better in comment above is the reason a checkbox should use an ItemListener over ActionListener due to the Event type that is returned.
February 25, Java Leave a comment. Questions: Closed. This question needs to be more focused. It is not currently accepting answers.
Want to improve this question? Update the question so it focuses on one problem only by editing this p Add menu. EventQueue; import java. ActionEvent; import java. ActionListener; import java.
ItemEvent; import java. ItemListener; import javax. JCheckBox; import javax. JFrame; import javax.
JCheckBox: addActionListener(ActionListener lis) : JCheckBox « javax.swing « Java by API
PLAIN,20 ; display. PLAIN; if bold. Selecting child rows from parent row using selenium webdriver with java-Exceptionshub February 25, Java Leave a comment Questions: Closed.Checkboxes allow the user to select one or more options from a set.
Typically, you should present each checkbox option in a vertical list. To create each checkbox option, create a CheckBox in your layout.
Because a set of checkbox options allows the user to select multiple items, each checkbox is managed separately and you must register a click listener for each one. When the user selects a checkbox, the CheckBox object receives an on-click event. The value for this attribute must be the name of the method you want to call in response to a click event. The Activity hosting the layout must then implement the corresponding method.
For example, here are a couple CheckBox objects in a list:. Within the Activity that hosts this layout, the following method handles the click event for both checkboxes:. The method you declare in the android:onClick attribute must have a signature exactly as shown above.
Specifically, the method must:. Tip: If you need to change the checkbox state yourself, use the setChecked boolean or toggle method. Content and code samples on this page are subject to the licenses described in the Content License. App Basics. Build your first app. App resources. Resource types.
App manifest file. App permissions. Device compatibility. Multiple APK support. Adding wearable features to notifications. Creating wearable apps. Creating custom UIs. Sending and syncing data. Creating data providers.
Creating watch faces. Android TV.Following is the pictorial representation of user interface UI or input controls in android application. Generally, in android the user interface of an app is made with a collection of View and ViewGroup objects. The ViewGroup is a subclass of View and it will act as a base class for layouts and layout parameters. The ViewGroup will provide invisible containers to hold other Views or ViewGroups and to define the layout properties.
The layout file must contain only one root element, which must be a View or ViewGroup object. Once we define the root element, then we can add additional layout objects or widgets as a child elements to build View hierarchy that defines our layout.
In android, each input control is having a specific set of events and these events will be raised when the user performs particular action like, entering the text or touches the button. Once we are done with the creation of layout with UI controls, we need to load the XML layout resource from our activity onCreate callback method like as shown below.
If you observe above code we are calling our layout using setContentView method in the form of R.
If we want to create UI elements at runtime, we need to create our own custom View and ViewGroup objects programmatically with required layouts. By creating a custom View and ViewGroups programmatically, we can define UI controls in layouts based on our requirements in android applications.
We have a different type of UI controls available in android to implement the user interface for our android applications. In android, TextView is a user interface control that is used to display the text to the user.
Java AWT Checkbox
In android, EditText is a user interface control which is used to allow the user to enter or modify the text. In android, AutoCompleteTextView is an editable text view which is used to show the list of suggestions based on the user typing text. The list of suggestions will be shown as a dropdown menu from which the user can choose an item to replace the content of the textbox.
In android, Button is a user interface control that is used to perform an action when the user clicks or tap on it. To know more about Button in android check this, Android Buttons with Examples. In android, Image Button is a user interface control that is used to display a button with an image to perform an action when the user clicks or tap on it. Generally, the Image button in android looks similar as regular Button and perform the actions same as regular button but only difference is for image button we will add an image instead of text.
In android, Checkbox is a two-states button that can be either checked or unchecked.
Android Checkbox and Textview in ListView Tutorial
In android, Radio Button is a two-states button that can be either checked or unchecked and it cannot be unchecked once it is checked. In android, Radio Group is used to group one or more radio buttons into separate groups based on our requirements.
In case if we group radio buttons using the radio group, at a time only one item can be selected from the group of radio buttons. In android, ProgressBar is a user interface control which is used to indicate the progress of an operation. In android, Spinner is a drop-down list which allows a user to select one value from the list. To know more about Spinner, check this Android Spinner with Examples. We learn all android user interface UI controls in next chapters in detailed manner with examples.Examples and practices described in this page don't take advantage of improvements introduced in later releases and might use technology no longer available.
Action listeners are probably the easiest — and most common — event handlers to implement. 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 buttonchooses a menu itempresses Enter in a text field.
The result is that an actionPerformed message is sent to all action listeners that are registered on the relevant component. In general, to detect when the user clicks an onscreen button or does the keyboard equivalenta program must have an object that implements the ActionListener interface.
The program must register this object as an action listener on the button the event sourceusing the addActionListener method. When the user clicks the onscreen button, the button fires an action event. This results in the invocation of the action listener's actionPerformed method the only method in the ActionListener interface. The single argument to the method is an ActionEvent object that gives information about the event and its source.
Let us write a simple program which displays how many number of times a button is clicked by the user. First, here is the code that sets up the TextFieldbutton and numClicks variable:. We would like to handle the button-click event, so we add an action listener to the button b as below:.
In the above code, Button b is a component upon which an instance of event handler class AL is registered. Now, we want to display the text as to how many number of times a user clicked button.
We can do this by writing the code as below:. Now, when the user clicks the Button b, the button fires an action event which invokes the action listener's actionPerformed method. Each time the user presses the button, numClicks variable is appended and the message is displayed in the text field. More Examples: Beeper program example is available in this trail's introduction to events, Introduction to Event Listeners.
You can find the entire program in Beeper. The other example described in that section, MultiListener. The ActionListener Interface. Because ActionListener has only one method, it has no corresponding adapter class.
All rights reserved. Hide TOC.The Java ActionListener is notified whenever you click on the button or menu item. It is notified against ActionEvent. The ActionListener interface is found in java. It has only one method: actionPerformed.
The actionPerformed method is invoked automatically whenever you click on the registered component. The common approach is to implement the ActionListener. If you implement the ActionListener class, you need to follow 3 steps:. We can also use the anonymous class to implement the ActionListener. It is the shorthand way, so you do not need to follow the 3 steps:. JavaTpoint offers too many high quality services. Mail us on hr javatpoint.
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JCheckBox basic tutorial and examples
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How can I fix this? You get the error because you imported wrong package. You should import android. Learn more. Android: checkbox listener Ask Question. Asked 8 years, 6 months ago. Active 11 months ago. Viewed k times. I want to put a Listener over a CheckBox. Roman Rdgz Roman Rdgz Active Oldest Votes.
You can do this: satView. Chris Chris Thank you and here is how to remove it: stackoverflow. OnCheckedChangeListener are different. OnClickListener : satView. Martin Zeitler 39k 11 11 gold badges 74 74 silver badges bronze badges. It's really only one working solution when I wanted to listen a checkbox click actionnot its state like others solutions recommend there. OnCheckedChangeListener; So the callback should be : box.
Huang Huang 4, 3 3 gold badges 18 18 silver badges 20 20 bronze badges. Edric You could use this code. Arun Shankar Arun Shankar 1 1 gold badge 3 3 silver badges 12 12 bronze badges. Why are you passing a 'LinearLayout' to your 'changeVisibility LinearLayout layout, boolean isChecked ' method yet you're only changing one layout's visibility each time?