# Why do I sometimes see errors in the editor but not in the problems view?

By default the AspectJ editor is used for files with the .aj extension and the Java editor for files with the .java extension. Some experienced AspectJ users may wish to use AspectJ function in .java files such as referring to ITD methods or fields, using inner aspects, implementing interfaces defined in aspects or calling methods on aspects. In this case you will see errors in the Java editor (although there will not be errors in the problems view). You may wish to either convert the file extension to .aj or use the AspectJ editor.

To open a .java file with the AspectJ editor right click, then select Open With > AspectJ/Java Editor. To use the AspectJ editor for all .java files select Window > Preferences > Workbench > File Associations. Select .java in the right-hand window, then use the section below to change the default editor.

AspectJ editor

Creating a new aspect
Converting file extensions