IntelliJ IDEA performs two different validity checks:
- On-the-fly validation.
- Full validation.
On-the-fly validation is available for all Web content files and is performed as you edit the file. IntelliJ IDEA checks well-formedness, that is, detects various violations of syntax requirements, such as unclosed tags, wrong end-tag name, duplicate tags, unresolved links, etc. All encountered errors are highlighted in the editor.
However, this form of code validation is rather soft, that is, not all requirements are taken into account.
Full validation involves structure validation in addition to well-formedness check. Full validation is available for files that are associated with an XSD (XML Schema Definition) Schema or contain a Data Type Definition (DTD). IntelliJ IDEA checks whether the structure of your XML file complies with the structure defined in the corresponding DTD or Schema.
Check results are provided as a Message View.
- Open the desired XML file in the editor, or just select it in the Project tool window.
- On the context menu, choose .