# 7. Annotator
Sample implementation of annotator highlighting resolved and unresolved Simple language properties in Java strings.
**Reference**: [](syntax_highlighting_and_error_highlighting.md#annotator)
**Code**: [`SimpleAnnotator`](%gh-sdk-samples-master%/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleAnnotator.java)
**Testing**: [](annotator_test.md)
An `Annotator` helps highlight and annotate any code based on specific rules.
This section adds annotation functionality to support the Simple Language in the context of Java code.
## Required Project Configuration Changes
Classes defined in this step of the tutorial depend on `com.intellij.psi.PsiLiteralExpression` (the PSI representation for String literals in Java code) at runtime.
Using `PsiLiteralExpression` [introduces a dependency](plugin_compatibility.md#modules-specific-to-functionality) on `com.intellij.java`.
Beginning in version 2019.2, a dependency on Java plugin [must be declared explicitly](plugin_compatibility.md#java).
First, add a dependency on the Java plugin in the Gradle build script:
```kotlin
intellij {
plugins.set(listOf("com.intellij.java"))
}
```
```groovy
intellij {
plugins = ['com.intellij.java']
}
```
Then, declare the dependency in [plugin.xml](plugin_configuration_file.md) (use code insight)
```xml
com.intellij.java
```
## Define an Annotator
The [`SimpleAnnotator`](%gh-sdk-samples-master%/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleAnnotator.java) subclasses [`Annotator`](%gh-ic%/platform/analysis-api/src/com/intellij/lang/annotation/Annotator.java).
Consider a literal string that starts with "simple:" as a prefix of a Simple Language key.
It isn't part of the Simple Language, but it is a useful convention for detecting Simple Language keys embedded as string literals in other languages, like Java.
Annotate the `simple:key` literal expression, and differentiate between a well-formed vs. an unresolved property.
> The use of new `AnnotationHolder` syntax starting 2020.2, which uses the builder format.
>
{style="note"}
```java
```
{src="simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleAnnotator.java" include-symbol="SimpleAnnotator"}
> If the above code is copied at this stage of the tutorial, then remove the line below the comment "** Tutorial step 19. …" The quick fix class in that line is not defined until later in the tutorial.
>
## Register the Annotator
Using the `com.intellij.annotator` extension point in the plugin configuration file, register the Simple Language annotator class for `JAVA` language:
```xml
```
## Run the Project
Run the plugin by using the Gradle [`runIde`](creating_plugin_project.md#running-a-plugin-with-the-runide-gradle-task) task.
As a test, define the following Java file containing a Simple Language `prefix:value` pair:
```java
public class Test {
public static void main(String[] args) {
System.out.println("simple:website");
}
}
```
Open this Java file in an IDE Development Instance running the `simple_language_plugin` to check if the IDE resolves a property:
{width="800"}
If the property is an undefined name, the annotator flags the code with an error.
{width="800"}
Try changing the Simple Language [color settings](syntax_highlighter_and_color_settings_page.md#run-the-project) to differentiate the annotation from the default language color settings.