# 11. Find Usages Provider

> For the complete documentation index, see [llms.txt](https://plugins.jetbrains.com/docs/intellij/llms.txt).

> **TL;DR**
> Reference: [Find Usages](find-usages.html)
>
>
>
> Code: [SimpleFindUsagesProvider](https://github.com/JetBrains/intellij-sdk-code-samples/tree/main/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleFindUsagesProvider.java)
>
>
>
> Testing: [8. Find Usages Test](find-usages-test.html)

> **Tip:**
> This page is part of multi-step [Custom Language Support Tutorial](custom-language-support-tutorial.html). All previous steps must be executed in sequence for the code to work.

A `FindUsagesProvider` uses a word scanner to build an index of words in every file. A scanner breaks the text into words and defines the context for each word.

## Define a Find Usages Provider

The [SimpleFindUsagesProvider](https://github.com/JetBrains/intellij-sdk-code-samples/tree/main/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleFindUsagesProvider.java) implements [FindUsagesProvider](https://github.com/JetBrains/intellij-community/tree/idea/263.7307.200/platform/indexing-api/src/com/intellij/lang/findUsages/FindUsagesProvider.java). Using the [DefaultWordsScanner](https://github.com/JetBrains/intellij-community/tree/idea/263.7307.200/platform/indexing-impl/src/com/intellij/lang/cacheBuilder/DefaultWordsScanner.java) ensures the scanner implementation is thread-safe. See the comments in `FindUsagesProvider` for more information.

```JAVA
final class SimpleFindUsagesProvider implements FindUsagesProvider {

  @Override
  public WordsScanner getWordsScanner() {
    return new DefaultWordsScanner(new SimpleLexerAdapter(),
        SimpleTokenSets.IDENTIFIERS,
        SimpleTokenSets.COMMENTS,
        TokenSet.EMPTY);
  }

  @Override
  public boolean canFindUsagesFor(@NotNull PsiElement psiElement) {
    return psiElement instanceof PsiNamedElement;
  }

  @Nullable
  @Override
  public String getHelpId(@NotNull PsiElement psiElement) {
    return null;
  }

  @NotNull
  @Override
  public String getType(@NotNull PsiElement element) {
    if (element instanceof SimpleProperty) {
      return "simple property";
    }
    return "";
  }

  @NotNull
  @Override
  public String getDescriptiveName(@NotNull PsiElement element) {
    if (element instanceof SimpleProperty) {
      return ((SimpleProperty) element).getKey();
    }
    return "";
  }

  @NotNull
  @Override
  public String getNodeText(@NotNull PsiElement element, boolean useFullName) {
    if (element instanceof SimpleProperty) {
      return ((SimpleProperty) element).getKey() +
          SimpleAnnotator.SIMPLE_SEPARATOR_STR +
          ((SimpleProperty) element).getValue();
    }
    return "";
  }

}
```

## Register the Find Usages Provider

The `SimpleFindUsagesProvider` implementation is registered with the IntelliJ Platform in the plugin configuration file using the [com.intellij.lang.findUsagesProvider](https://jb.gg/ipe?extensions=com.intellij.lang.findUsagesProvider) extension point .

```XML
<extensions defaultExtensionNs="com.intellij">
  <lang.findUsagesProvider
      language="Simple"
      implementationClass="org.intellij.sdk.language.SimpleFindUsagesProvider"/>
</extensions>
```

## Run the Project

[Run](creating-plugin-project.html#running-the-plugin) the plugin.

The IDE now supports [Find Usages](https://www.jetbrains.com/help/idea/find-highlight-usages.html) for any property with a reference:

![Find Usages](images/find_usages.png)