For creating relationship links between node elements, IntelliJ IDEA provides a special mode, in which drag-and-drop technique can be used for drawing links. As a link is created, the corresponding extends / implements clause is generated in the underlying source code. So doing, the extends link is represented with a solid line, and the implements link is represented with a dotted line.

To create a link between node elements
  1. Make sure that edgemode.png is pressed on the diagram toolbar.
  2. Draw a link from the source to a target node.
  3. Specify whether the target class should be declared abstract, or implement required abstract methods:

    umlAddLink.png

To delete a link
  1. Select a link between two node.
  2. Press ⌦, ⌫, ⌘⌫, ⌦, ⌫ or ⌘⌫⌦, ⌫, ⌘⌫, ⌦, ⌫ or ⌘⌫⌦, ⌫, ⌘⌫, ⌦, ⌫ or ⌘⌫Delete, ⌦ or ⌦Delete, ^ D, ⌦, ⌃D, ⌦ or ⌃D.
  3. In the dialog box that opens, confirm deletion:

    umlDeleteLink.png