[//]: # (title: Modifying Project View Structure)

<!-- Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file. -->

This tutorial is meant to illustrate how the project tree structure view appearance can be modified programmatically.
If you need to know more about basic concepts of the project view in IntelliJ-based IDEs, please refer to the [Project Tool Window](https://www.jetbrains.com/help/idea/project-tool-window.html) section in IntelliJ IDEA Web Help.

This topic describes the [treeStructureProvider](https://github.com/JetBrains/intellij-sdk-code-samples/tree/main/tree_structure_provider) sample plugin.

The steps below show how to filter out and keep visible only text files and directories in the Project View Panel.

Other use cases include:
- grouping/nesting related entries, e.g., [GUI Designer](https://www.jetbrains.com/help/idea/gui-designer-basics.html) <path>.form</path> file and related bound class ([`FormMergerTreeStructureProvider`](upsource:///plugins/ui-designer/src/com/intellij/uiDesigner/projectView/FormMergerTreeStructureProvider.java)).
- provide additional "nested" nodes, e.g., contents of custom archive file

## Register Custom TreeStructure Provider

Add new `com.intellij.treeStructureProvider` extension to the [plugin.xml](https://github.com/JetBrains/intellij-sdk-code-samples/blob/main/tree_structure_provider/src/main/resources/META-INF/plugin.xml)

```java
<extensions defaultExtensionNs="com.intellij">
  <treeStructureProvider implementation="org.intellij.sdk.treeStructureProvider.TextOnlyTreeStructureProvider"/>
</extensions>
```

## Implement Custom TreeStructureProvider

To provide custom Structure View behaviour, implement [`TreeStructureProvider`](upsource:///platform/editor-ui-api/src/com/intellij/ide/projectView/TreeStructureProvider.java) with the nodes filtering logic in `modify()` method.
The example below shows how to filter out all the Project View nodes except those which correspond to text files and directories.

```java
```
{src="tree_structure_provider/src/main/java/org/intellij/sdk/treeStructureProvider/TextOnlyTreeStructureProvider.java"}

## Compile and Run the Plugin

See [Code Samples](code_samples.md) on how to set up and run the plugin.

After going through the steps described above, you can see only text files and directories belonging to a project in the Project View.

![Text Files](text_only.png)