How to Use IntelliJ IDEA Diagrams to Explore Java Inheritance and Source Code

01 View Inheritance Diagram

In the editor tab of the class you want to inspect, right‑click and choose Diagrams → Show (opens in the same tab) or Show … Popup (opens as a floating window). The same option is also available by right‑clicking the class in the project tree.

The resulting diagram displays inheritance with solid blue arrows and interface implementation with dashed green arrows, as illustrated with a custom Servlet subclass.

02 Optimize the Diagram

2.1 Remove Unwanted Classes

If the diagram includes classes you do not care about (e.g., Object or Serializable), select them and press the Delete key. After cleaning, the diagram shows only the relevant inheritance chain.

2.2 Show Detailed Member Information

Right‑click the diagram and select Show Categories to expand attributes, methods, constructors, etc. The toolbar provides the same shortcut. You can also filter by visibility level via Change Visibility Level to display only protected and higher members.

2.3 Add Additional Classes

To examine relationships with other classes, choose Add Class to Diagram , type the class name (e.g., Student), and the class appears in the diagram. If no arrows connect it, the class has no inheritance or interface ties to the existing nodes.

2.4 Zoom and Pan

Holding the Alt key activates a magnifier, allowing you to zoom in on dense parts of the diagram.

03 Jump to Source Code

Double‑click a class in the diagram to open its source file. In the method list, right‑click a method and choose Jump to Source to navigate directly to its implementation.

The Structure view (accessible from the left sidebar) lists all members of the current class; clicking an entry jumps to that member in the editor.

Using these IDEA features makes exploring class hierarchies and reading framework source code much more comfortable and efficient.