Eclipse does not display /target/classes folder in "project explorer view"

The Project Explorer view defaults to not showing the output folders.

To change this click the small down arrow at the top right of the view and choose the Customize View option. Uncheck the 'Java output folders' option in the filters list.

Note that from Eclipse 2019-12 onwards the small down arrow is replaced by a 'hamburger' menu (three vertical dots).

Try this Click on Filters and customization and uncheck *.class resources