# Indexing PDF documents on Android

Nutrient supports fast and efficient full-text search in PDF documents through [`PdfLibrary`](https://www.nutrient.io/api/android/nutrient/com.pspdfkit.document.library/-pdf-library/index.html). This guide describes how to get started with [`PdfLibrary`](https://www.nutrient.io/api/android/nutrient/com.pspdfkit.document.library/-pdf-library/index.html) alongside the [`LibraryDataSource`](https://www.nutrient.io/api/android/nutrient/com.pspdfkit.document.library/-library-data-source/index.html) API.

This guide covers the recommended approach using [`LibraryDataSource`](https://www.nutrient.io/api/android/nutrient/com.pspdfkit.document.library/-library-data-source/index.html) and [`LibraryFileSystemDataSource`](https://www.nutrient.io/api/android/nutrient/com.pspdfkit.document.library/-library-file-system-data-source/index.html). For the legacy approach using direct document enqueueing, refer to the [legacy approach](#legacy-approach) section below.

## Getting started (recommended)

The recommended way to use [`PdfLibrary`](https://www.nutrient.io/api/android/nutrient/com.pspdfkit.document.library/-pdf-library/index.html) is through the [`LibraryDataSource`](https://www.nutrient.io/api/android/nutrient/com.pspdfkit.document.library/-library-data-source/index.html) API, which provides automatic directory monitoring and more efficient indexing. This approach uses [`LibraryFileSystemDataSource`](https://www.nutrient.io/api/android/nutrient/com.pspdfkit.document.library/-library-file-system-data-source/index.html) to automatically index all PDFs in a specified directory:

```kotlin

// Create the library instance.
val libraryDbPath = File(context.filesDir, "pdf_library.db").absolutePath
val library = PdfLibrary(libraryDbPath)

// Set up the file system data source for a directory.
val documentsDirectory = File(context.filesDir, "documents")
val dataSource = LibraryFileSystemDataSource(library, documentsDirectory)

// Configure the library to use the data source.
library.dataSource = dataSource

// Index all documents in the directory.
library.updateIndexFromDataSource()

```

Check out our [Catalog example](https://github.com/PSPDFKit/pspdfkit-android-catalog/blob/master/app/src/main/java/com/pspdfkit/catalog/examples/kotlin/IndexedFullTextSearchExample.kt) to see it in action.

### Advanced configuration

[`LibraryFileSystemDataSource`](https://www.nutrient.io/api/android/nutrient/com.pspdfkit.document.library/-library-file-system-data-source/index.html) provides several configuration options:

```kotlin

val dataSource = LibraryFileSystemDataSource(library, documentsDirectory) { documentSource ->
    // Optional document handler — return `true` to index, `false` to skip.
    // You can use this to filter documents based on custom criteria.!documentSource.title?.contains("draft", ignoreCase = true)?: true
}

// Configure file extension filtering (defaults to "pdf" only).
// At the time of release, only PDF files have been tested.
dataSource.allowedPathExtensions = setOf("pdf")

// Enable explicit mode for manual change notifications (advanced).
dataSource.isExplicitModeEnabled = false // Default: automatic directory monitoring

```

## Searching with LibraryDataSource

Once your [`PdfLibrary`](https://www.nutrient.io/api/android/nutrient/com.pspdfkit.document.library/-pdf-library/index.html) is set up with a [`LibraryDataSource`](https://www.nutrient.io/api/android/nutrient/com.pspdfkit.document.library/-library-data-source/index.html), you can search across all indexed documents. The library enables you to query for the current indexing state using [`isIndexing()`](https://www.nutrient.io/api/android/nutrient/com.pspdfkit.document.library/-pdf-library/is-indexing.html) and check individual document status with [`getIndexStatusForUID()`](https://www.nutrient.io/api/android/nutrient/com.pspdfkit.document.library/-pdf-library/get-index-status-for-u-i-d.html).

The search results are delivered through the [`QueryResultListener`](https://www.nutrient.io/api/android/nutrient/com.pspdfkit.document.library/-query-result-listener/index.html) callbacks. Basic results (document UID to page numbers mapping) come through `onSearchCompleted`, while text preview snippets are delivered via `onSearchPreviewsGenerated` when [`generateTextPreviews()`](https://www.nutrient.io/api/android/nutrient/com.pspdfkit.document.library/-query-options/-builder/generate-text-previews.html) is enabled.

Here’s an example search with `LibraryDataSource`:

```kotlin

// Set up search result options.
val options = QueryOptions.Builder().generateTextPreviews(true).previewRange(20, 120).build()

// Run the search. The search will run on a background thread and the callbacks will be called
// from the background thread as well.
library.search("looking for this text", options, object : QueryResultListener {
    override fun onSearchCompleted(p0: String, p1: Map<String, Set<Int>>) {
        // Results contain UID → set of pages mapping.
    }

    override fun onSearchPreviewsGenerated(p0: String, p1: Map<String, Set<QueryPreviewResult>>) {
    	// Previews contain UID → set of `QueryPreviewResult` mappings.
    }
})

```

## Legacy approach

The following approach using `enqueueDocuments()` is legacy and isn’t recommended for new implementations. Use the [`LibraryDataSource`](https://www.nutrient.io/api/android/nutrient/com.pspdfkit.document.library/-library-data-source/index.html) approach above instead.

The legacy approach requires manually managing individual [`PdfDocument`](https://www.nutrient.io/api/android/nutrient/com.pspdfkit.document/-pdf-document/index.html) instances:

```kotlin

// Assume that you have two valid `PdfDocument`s.
val doc1 : PdfDocument =...
val doc2 : PdfDocument =...

// The library will be saved in your application's files directory.
val library = PdfLibrary.get(File(context.filesDir, "library.db").absolutePath)
library.enqueueDocuments(listOf(doc1, doc2))

```

## Resource management

When using [`LibraryFileSystemDataSource`](https://www.nutrient.io/api/android/nutrient/com.pspdfkit.document.library/-library-file-system-data-source/index.html), remember to clean up resources when done:

```kotlin

// In your activity's `onDestroy()` or when finished.
dataSource.cleanup()

```
---

## Related pages

- [PDF search matching options on Android](/guides/android/search/indexed-full-text-search/matching-options.md)