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jvx:reference [2020/06/10 13:05] cduncan [Following the chain] |
jvx:reference [2020/06/10 13:12] cduncan [Notes on the launcher] |
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So we need two classes, the ''%%ILauncher%%'' implementation that knows how to start the technology and the ''%%IApplication%%'' implementation. That we already knew, so let’s try to put this into code. For simplicity reasons (and because I don’t want to write a complete factory from scratch for this example), we will reuse the Swing implementation and write a new launcher and application for it. | So we need two classes, the ''%%ILauncher%%'' implementation that knows how to start the technology and the ''%%IApplication%%'' implementation. That we already knew, so let’s try to put this into code. For simplicity reasons (and because I don’t want to write a complete factory from scratch for this example), we will reuse the Swing implementation and write a new launcher and application for it. | ||
- | ===== Entry point ===== | + | ===== Entry Point ===== |
- | The ''%%Main%%'' class that we will use as example is very straightforward: | + | The ''%%main%%'' class that we will use as example is very straightforward: |
<code java> | <code java> | ||
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} | } | ||
</code> | </code> | ||
- | All we have to do there is start the launcher itself. As the comment suggests, there might be work required for a “real” application startup. For this example, it is all we need to do. Of course we could also directly embed this little function into the launcher implementation itself, to save us one class. | + | All we have to do there is start the launcher itself. As the comment suggests, there might be work required for a “real” application startup. For this example, it is all we need to do. Of course, we could also directly embed this little function into the launcher implementation itself to save us one class. |
- | ===== The launcher ===== | + | ===== The Launcher ===== |
- | The ''%%ILauncher%%'' implementation on the other hand contains quite some logic, but nothing not manageable: | + | The ''%%ILauncher%%'' implementation, on the other hand, contains quite some logic but nothing not manageable: |
<code java> | <code java> | ||
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} | } | ||
</code> | </code> | ||
- | In short, the launcher is kicking off the Swing thread by invoking the startup method on the main Swing thread. This startup method will instantiate the factory and then create the application. From there we only need to set it visible and then our application has started. | + | In short, the launcher is kicking off the Swing thread by invoking the startup method on the main Swing thread. This startup method will instantiate the factory and then create the application. From there, we only need to set it to visible and then our application has started. |
- | The launcher extends from ''%%SwingFrame%%'', that is required because there hasn’t been a factory created yet which could be used by UI components to create themselves. If we’d try to use an UI component before creating/setting a factory, we would obviously see the constructor of the component fail with a ''%%NullPointerException%%''. | + | The launcher extends from ''%%SwingFrame%%''. That is required because there hasn’t been a factory created yet that could be used by UI components to create themselves. If we’d try to use an UI component before creating/setting a factory, we would see the constructor of the component fail with a ''%%NullPointerException%%''. |
- | The method ''%%startup()%%'' is invoked on the main Swing thread, which also happens to be the main UI thread for [[https://sourceforge.net/projects/jvx/|JVx]] in this application. Once we are on the main UI thread we can create the application, add it and then set everything to visible. | + | The method ''%%startup()%%'' is invoked on the main Swing thread, which also happens to be the main UI thread for [[https://sourceforge.net/projects/jvx/|JVx]] in this application. Once we are on the main UI thread, we can create the application, add it, and then set everything to visible. |
- | ===== The application ===== | + | ===== The Application ===== |
- | The ''%%IApplication%%'' implementation is quite short, because we extend ''%%com.sibvisions.rad.application.Application%%'', an ''%%IApplication%%'' implementation created with UI components. | + | The ''%%IApplication%%'' implementation is quite short because we extend ''%%com.sibvisions.rad.application.Application%%'', an ''%%IApplication%%'' implementation created with UI components. |
<code java> | <code java> | ||
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} | } | ||
</code> | </code> | ||
- | Because the launcher has previously started the technology and created the factory we can from here on now use UI components, which means we are already independent of the underlying technology. So the ''%%IApplication%%'' implementation can already be used with different technologies and is completely independent. | + | Because the launcher has previously started the technology and created the factory, we can now use UI components, which means we are already independent of the underlying technology. So, the ''%%IApplication%%'' implementation can already be used with different technologies and is completely independent. |
- | ===== Notes on the launcher ===== | + | ===== Notes on the Launcher ===== |
- | As you might have noticed, in our example the launcher is a (window) frame, that makes sense for nearly every desktop GUI toolkit as they all depend upon a window as main method to display their applications. But the launcher could also be simpler, for example just a call to start the GUI thread. Or it could be something completely different, for example an incoming HTTP request. | + | As you might have noticed, in our example the launcher is a (window) frame. That makes sense for nearly every desktop GUI toolkit as they all depend upon a window as main method to display their applications. But the launcher could also be simpler: for example, just a call to start the GUI thread. Or it could be something completely different: for example, an incoming HTTP request. |
- | Also don’t forget that the launcher is providing additional functionality to the application, like saving file handles, reading and writing the configuration and similar platform and toolkit dependent operations, see the [[https://sourceforge.net/p/jvx/code/HEAD/tree/trunk/java/swing/src/com/sibvisions/rad/ui/swing/impl/SwingApplication.java|launcher for Swing for further details]]. | + | Also, don’t forget that the launcher is providing additional functionality to the application, like saving file handles, reading and writing the configuration, and similar platform and toolkit-dependent operations. See the [[https://sourceforge.net/p/jvx/code/HEAD/tree/trunk/java/swing/src/com/sibvisions/rad/ui/swing/impl/SwingApplication.java|launcher for Swing for further details]]. |
===== Conclusion ===== | ===== Conclusion ===== |