IntelliJ IDEA 2019.2 Help

Language injections

Language injections let you work with pieces of code inside string literals as well as tags or attributes in XML-like languages.

When you have a piece of formal language (such as HTML, CSS, XML, RegExp, and so on) inside a string literal, a tag, or an attribute, you can get comprehensive language assistance for editing that piece.

Temporarily inject a language

  1. Position the caret inside the string literal, tag, or attribute, in which you want to inject a language and press Alt+Enter (or use the intention action icon Intention action icon).

  2. Select Inject language or reference and choose the language you want to inject.

Open a code fragment in the dedicated editor section

  1. Position the caret within the injected code piece and press Alt+Enter (or use the intention action icon Intention action icon).

  2. Select Edit <language ID> Fragment.

    IntelliJ IDEA will open a dedicated editor section for editing the code with the injected language. This editor provides full code assistance, including code completion, inspections, intentions and code style actions.

Use language injection comments

Add a blank line before the target string literal, and type the following comment:

-- language=<language_ID>

For comments, use the syntax of the language you want to inject. Language IDs are generally intuitive, for example, SQL, RegExp, XML, HTML.

A language fragment may be combined with a prefix and a suffix that act together as a wrapper, turning the fragment into a syntactically complete language unit. When editing your code, you can see prefixes and suffixes only in the fragment editor. They are not shown in the main editor.

The prefix and the suffix can be included in the injection comment as follows:

// language=<language_ID> prefix=<prefix> suffix=<suffix>

Use the @Language annotation

In some languages (for example, in Java, Groovy, or Kotlin), you can also use the @Language("language_ID") annotation to inject a language.

  1. On a blank line before the target string literal, type @Language("language_ID").

  2. Position the caret at the annotation, press Alt+Enter and select Add 'annotations' to classpath.

    The IDE will prompt you to download the library with annotations from Maven.

  3. In the search field, type org.jetbrains:annotations:16.0.2 if you use JDK 1.8 or higher.

    For JDK 1.5, 1.6 or 1.7, type org.jetbrains:annotations-java5:16.0.2.

  4. Click OK.

  5. Press Alt+Enter and select Import class.

Cancel injections

  1. Position the caret at the code fragment and press Alt+Enter (or use the intention action icon the Intention action button).

  2. Select Uninject language or reference.

To cancel a language injection, you can also delete the injection comment or annotation.

Configure injection rules

You can configure language injection rules on the Editor | Language Injections page of IntelliJ IDEA settings Ctrl+Alt+S.

Language injections settings

All pre-defined injection rules are configured for the Built-in scope. In other words, they are global (and therefore available in all IntelliJ IDEA projects). Custom rules can be configured for the IDE or for one project only. To change the scope of custom injections, use the the Move to Project/IDE scope button.

To configure custom injection rules, click the Add button to add a new rule, or copy a predefined rule and change its settings.

Example: inject SQL in Java

You can configure the settings so that each time you use a certain method, the IDE will inject the selected language, for example, SQL.

  1. In the Setting/Preferences dialog Ctrl+Alt+S, go to Editor | Language Injections.

  2. Click the Add button and select Java Parameter.

  3. From the ID list, select SQL.

  4. In the Class Methods field, enter the method that you want to take an SQL parameter. You can type the method manually, or click the Browse button and select the method in the Select Class dialog.

    If the method takes multiple parameters, they will be displayed in the dialog. Select the ones that you want to use.

  5. Apply the changes and close the dialog.

Last modified: 19 August 2019

See Also