There is no this pointer in a static method. (I don’t believe this code will even compile.) You shouldn’t be doing these things in a static method like main(); set things up in a constructor. I didn’t compile or run this to see if it actually works, but give it a try. public class Calc … Read more
This is not an immediate answer to your question, but knowing (or at least suspecting) what it is that you wish to offer (a simple paint program), I suggest starting with this approach based around a BufferedImage as the painting surface.. import java.awt.*; import java.awt.RenderingHints.Key; import java.awt.event.*; import java.awt.image.BufferedImage; import java.io.File; import java.io.IOException; import java.util.HashMap; … Read more
In order to reflect changes after adding/removing or resizing a component that is on a visible container call revalidate() and repaint() on the containers instance after adding/removing or resizing the component. Though this will not work in your code the main reason being inside JButton classes you recreate a new instance of MainPanel when in … Read more
Because ClockListener is a nested class (lower), the enclosing instance (upper) can access the listener’s private fields. If you have a reference to an instance of ClockListener, ClockListener cl = new ClockListener(); you can use it to initialize your timer Timer t = new Timer(1000, cl); and you can use it in your test: if … Read more
Generally speaking, where you have a limited set of key inputs, key bindings are a better choice. KeyListener suffers from issues related to focusability and with other controls in the GUI, focus will constantly be moving away from the component (with the KeyListener) all the time. A simple solution would be to use the Actions … Read more
I’d use a JToggelButton, as shown here, or delegate to the contained buttons, as @duffymo suggests. If you really need a custom OnOffSwitchEvent, the standard wiring is outlined in EventListenerList, an instance of which is contained in every JComponent. Addendum: Here’s an example of delegating to a ButtonGroup containing two buttons. The label is decorated … Read more
As a general rule, you should not have your GUI classes, such as the class extending JPanel, implement any listener interfaces, and in fact you should strive for just the opposite — to separate the control functions of the program (the listeners and the like) from the view functions of the program (the GUI). So … Read more
another way as implementing inner ActionListener (with setActionCommand(String actionCommand)) for whole JMenu is wrote java.swing.Action for each of JMenuItem or implements EventHandler (seems like as valid for all Listeners that I tried) example about JButtons and with implemented ActionListener and EventHandler (both Listeners firing events) EDIT: EventHandler os too hacky, because in Swing aren’t another … Read more
From a JavaRanch Forum post. Key press and release handlers are added on the scene and update movement state variables recorded in the application. An animation timer hooks into the JavaFX pulse mechanism (which by default will be capped to fire an event 60 times a second) – so that is a kind of game … Read more
Two ways: 1. Implement ActionListener in your class, then use jBtnSelection.addActionListener(this); Later, you’ll have to define a menthod, public void actionPerformed(ActionEvent e). However, doing this for multiple buttons can be confusing, because the actionPerformed method will have to check the source of each event (e.getSource()) to see which button it came from. 2. Use anonymous … Read more