NetBeans: The Definitive Guide

Chapter 17. Internals of the Running IDE

Writing code to interact with a running application requires knowledge of what is going on behind the scenes in that application and what resources are available to you at runtime. This chapter will acquaint you with what is going on behind the scenes in NetBeans.

The Activated Node(s)

One of the reasons many user interface components in NetBeans are explorer views is that explorer views have a concept of a Node or set of Nodes being activated. At any time, only one window has input focus, meaning that it is responding to the keyboard. Many windows contain tabbed panes—the component comprising each individual pane is a TopComponent. Whichever tab is displayed in the window that has focus is the active TopComponent. Many TopComponents display Nodes in one way or another. Multiple Nodes in an explorer view can be selected (by Shift- or Control-left-clicking them). The Nodes that are selected in the active TopComponent are “activated.” The activated nodes provide the context by which NetBeans decides what actions should be available, by enabling or disabling menu items and toolbar buttons. They also determine what properties should be shown in the global property sheet. For context-sensitive actions such as Compile, it is this context that determines if the action can be performed and what the target of that action is. Note that in the Code Editor, the selected node is determined by the cursor position. If you were to expand a Java class