Setting up Eclipse

For General Text Editing

1. Go to "Window -> Preferences" to open up the Preferences window.
2. Navigate to "General -> Editors -> Text Editors"
3. Check "Insert spaces for tabs" and set "Displayed tab width" to 4.

Optional but recommended step: check "Show whitespace characters". You can choose which characters to display, as well as their opacity, by clicking on "whitespace characters" (should be highlighted).

For Java

1. Go to "Window -> Preferences" to open up the Preferences window.
2. Navigate to "Java -> Code Style -> Formatter".
3. Create a new profile.
4. Click "Edit".
5. Under the "Indentation" tab, make sure that the "Tab Policy" is "Spaces only" and that "Indentation size"/"Tab size" are set to 4.

For Scala

1. Go to "Window -> Preferences" to open up the Preferences window.
2. Navigate to "Scala -> Formatter".
3. Under the "Indentation & Alignment" tab, set "Spaces to indent" to 2 and make sure "Indent using tabs" is NOT checked.
4. Navigate to "Scala -> Organize Imports".
5. Click "collapse into single import statement".

Note that Ctrl+Shift+F will reformat the open file.