Showing an element in the Package Explorer view

You can reveal an element's location in the Package Explorer view

In the Hierarchy or Outline view, select a type or one of its members.
From the selected element's pop-up menu, select Show in Package Explorer. If the Package Explorer is not already open, then it opens in the current perspective. The workbench navigates to the selected element.
From the Java editor's pop-up menu, select Show in Package Explorer (the currently edited compilation unit will be revealed)

Note: The element might not be revealed if Package Explorer filters are active or the Window > Preferences > Java > Appearance > Show Members in Package Explorer preference is cleared.

Java views

Setting execution arguments
Renaming a compilation unit
Opening a type in the Package Explorer
Organizing existing import statements

Java Base preference page
Package Explorer