Dive into Netbeans: Lookup

最新推荐文章于 2022-10-28 17:16:39 发布

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本文介绍了 Lookup 作为一种数据结构的应用方式，它使用 Class Objects 作为键，并以这些类实例的集合作为值。此外，Lookup 支持监听其内容的变化。文章还讨论了如何通过实现 Lookup 接口将对象作为提供者，使其他组件可以访问该对象的 Lookup。特别地，文中提到了 Nodes 也实现了 Lookup 提供者接口，并举例说明了在 Node 的 Lookup 中存储 DataObject 的用例。

Lookup as a Data Structure

So first let's have a look at Lookup as a data structure. A Lookup is a map with Class Objects as keys and a Set of instances of the key Class object as values. An additional feature of a Lookup is that you can listen for changes of what's in there.

Lookup.Provider

If your Object has a Lookup to store a bunch of stuff, you can make it accessible to others by implementing Lookup

Nodes

Nodes also implement Lookup.Provider so you can ask them for their Lookup as well. Something useful to store inside a Node's Lookup is the DataObject it may represent. If you're using Nodes you probably do so in combination with the Explorer API to display them. If you do that you'll usually create a lookup for your TopComponent with the help of the ExplorerManager: