Master IntelliJ IDEA Diagrams to Visualize Java Servlet Inheritance

While revisiting Java knowledge, the author found Servlet inheritance hierarchies confusing and discovered that IntelliJ IDEA's diagram tool can present them clearly.

Viewing the Diagram

In the class editor tab, right‑click and choose Diagrams → Show Diagram (or the popup version). The same option is also available from the project tree. The resulting diagram displays inheritance with blue solid arrows and interface implementation with green dashed arrows.

Cleaning Up Unwanted Classes

Select any class you don't need in the diagram and press the Delete key. After removing irrelevant nodes, the diagram becomes focused on the important Servlet hierarchy.

Showing Detailed Class Information

Right‑click a class and select Show Categories to expand properties, methods, constructors, etc. You can also use the toolbar button for the same effect. To filter methods by visibility, choose Change Visibility Level and set the desired level.

Adding Other Classes to the Diagram

Right‑click in the diagram area and select Add Class to Diagram , then type the class name you wish to include. The new class appears in the diagram, showing any relationships it may have.

Viewing Specific Source Code

Double‑click a class in the diagram, then right‑click a method and choose Jump to Source to open its implementation. The Structure view can also be used to list all methods; clicking a method jumps directly to its code.

Using these IDEA features makes exploring class relationships and understanding framework source code much more comfortable.