Select personalised content. Create a personalised content profile. Measure ad performance. Select basic ads. Create a personalised ads profile. Select personalised ads. Apply market research to generate audience insights. Measure content performance. Develop and improve products. List of Partners vendors. Share Flipboard Email. Paul Leahy. Other events are initiated by the user, for example,. Outline for Lecture Event handling. In our example from Lecture 13, we used frame.
This could also be done by having the HelloWorldSwing class implement a windowClosing method to exit the system:. Exercise: What other changes would we have to make in the code for the example? WindowListener is an example of an event-listener interface. In general, for each leaf Event class there is a corresponding listener.
Two exceptions are. Some interfaces, e. We could just implement all of these methods in a class like HelloWorldSwing. But, because this is tedious, the java. Adapters are classes that implement all of the methods in their corresponding interfaces, with null bodies.
If the programmer only wants to define a few methods of the interface, s he can extend an adapter class, and override a few of its methods. But take a look at stackoverflow. Catch ; System. GlassGhost GlassGhost GlassGhost: The problem is that main is static, and there's no such thing as this in a static function.
You need to create a new Catcher1 somewhere, and pass that instance instead. GlassGhost: The code that uses this is in a constructor, not in main. That's why it works. Move it to main , and i guarantee it won't. That's what people have been trying to tell you, and what your answer is trying to do. I don't give a damn what's on github -- i care what's on SO.
And what you have on SO is broken. GlassGhost: I don't think your answer is inadequate overall. The problem i see with it is that the code won't work as is -- you're trying to use this from main , which won't compile in any released version of Java. If that part were in a constructor instead, or if main created a new Catcher1 and used that instead of this , it should work, even in 1.
GlassGhost: "A method that is declared static is called a class method. A class method is always invoked without reference to a particular object. An attempt to reference the current object using the keyword this or the keyword super or to reference the type parameters of any surrounding declaration in the body of a class method results in a compile-time error. This is one of the strangest code styles I've ever seen — Eric.
Show 20 more comments. Ivan Ivan 5, 3 3 gold badges 21 21 silver badges 29 29 bronze badges. Disclaimer: I am the author of Signals. Ilya Gazman Ilya Gazman Or a program might have a single listener for all events from all sources. A program can even have more than one listener for a single kind of event from a single event source.
Multiple listeners can register to be notified of events of a particular type from a particular source. Also, the same listener can listen to notifications from different objects. Each event is represented by an object that gives information about the event and identifies the event source.
Event sources are often components or models, but other kinds of objects can also be event sources. Whenever you want to detect events from a particular component, first check the how-to section for that component. A list of the component how-to sections is here.
The how-to sections give examples of handling the events that you are most likely to care about. In How to Use Color Choosers , for instance, you will find an example of writing a change listener to track when the color changes in the color chooser.
The following example demonstrates that event listeners can be registered on multiple objects and that the same event can be sent to multiple listeners. The example contains two event sources JButton instances and two event listeners.
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