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    <p>A common use of classloaders is to isolate a JAR. If you have an application which uses plugins (<a href="http://www.eclipse.org/" rel="noreferrer">Eclipse</a>, <a href="http://maven.apache.org/" rel="noreferrer">Maven 2</a>), then you can have this situation: Plugin X needs jar A with version 1.0 while plugin Y need the same jar but version 2.0. X does not run with version 2.0, though.</p> <p>If you have classloaders, you can create partitions of classes (think of isolated islands connected by thin bridges; the bridges are the classloaders). This way, the classloaders can control what each plugin can see.</p> <p>When plugin X instantiates a class Foo, which has static fields, this is no problem and there won't be a mixup with the "same" class in plugin Y because each classloader will in fact create its own instance of the class Foo. You then have two classes in memory, where <code>cl1.getName().equals(cl2.getName())</code> is <code>true</code> but <code>cl1.equals(cl2)</code> is not. This means that instances of cl1 are not assignment compatible to instances of cl2. This can lead to strange <code>ClassCastExceptions</code> which say that <code>org.project.Foo</code> can't be assigned to <code>org.project.Foo</code>.</p> <p>Just like with remote islands, the two classes are not aware that the other one exists. Think of human clones which are born and then raised on different islands. From the point of view of the VM, there is no problem because instances of the type Class are handled like any other object: There can be several of them. That you think that some of them are "the same" doesn't matter to the VM.</p> <p>Another use for this pattern is that you can get rid of classes loaded this way: Just make sure that no one has a pointer to any object created from classes loaded from a classloader and then forget about the classloader, too. On the next run of the <a href="http://en.wikipedia.org/wiki/Garbage_collection_(computer_science)" rel="noreferrer">GC</a>, all classes loaded by this classloader are removed from memory. This allows you to "reload" your application without having to restart the whole VM.</p>
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    1. CONice analogy, the island one! +1
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A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

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