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POJava: How do I update a View when a Model's Collection is added to?
 

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  1. POJava: How do I update a View when a Model's Collection is added to?
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    <p>So I'm working on rewriting a program for a professor, and I have some questions related to the Model-View-Controller pattern. The program is called GraphViewer and is used to design and view graphs (as in Graph Theory, not Statistics). So far I have planned the structure thus:</p> <ul> <li>Models <ul> <li>VertexModel - Has id, location, color, and a collection of edges it is coincident to</li> <li>EdgeModel - Has the two vertices it spans, weight, color, and a couple other things</li> <li>GraphModel - Primarily, but not just, a collection of vertices and a collection of edges</li> </ul></li> <li>Views <ul> <li>VertexView - Paints its vertex, and has its own properties</li> <li>EdgeView - Paints its edge, and also has some of its own properties</li> <li>GraphView - Basically a JPanel that has a collection of vertex and edge views, when it gets a paint command, it also iterates through each collection of views and issues a paint command to them</li> </ul></li> <li>Controllers <ul> <li>GraphController - Takes care of interpreting user gestures for adding vertices, edges, etc. and updates the model.</li> </ul></li> </ul> <p>Now the first question I have is related to this plan: Should each model have a view--even though only the graphmodel is a JComponent? Now part of me says yes--because each vertex and edge might be drawn differently. But another part of me screams no to the kind-of parallel-list structure of a graphview having collections of views that correspond to models in the collections of the graphview's graphmodel (boy that's complicated). And somehow, I have to work in that the whole graphview must repaint if a vertex or edge model changes. I suppose the answer to this is also related to whether each model gets a controller. (Am I just approaching this wrong?)</p> <p>Somewhat tied to the answer of the first question is my second: how will I know to notify the graphview if a vertexmodel is added to the graphmodel's collection? If a whole new collection is set, it'll notify the view when it enters the setEdges() method. But what if I have to write getEdges().add(...)? Now the graphview needs to be notified of an update, but setEdges was never called...</p> <p>Thanks a bunch, as you can tell I'm kinda new to design patterns!</p>
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