--- title: "E-Learning" canonical_url: "https://www.nutrient.io/guides/android/samples/e-learning-kotlin/" md_url: "https://www.nutrient.io/guides/android/samples/e-learning-kotlin.md" last_updated: "2026-05-15T19:10:04.916Z" description: "Switch between documents while preserving view state, annotations, and bookmarks." --- # E-Learning Switch between documents while preserving view state, annotations, and bookmarks. [Get Started](https://www.nutrient.io/sdk/android/getting-started.md) [All Samples](https://www.nutrient.io/guides/android/samples.md) [Download](https://www.nutrient.io/guides/android/downloads.md) [Launch Demo](https://www.nutrient.io/demo/) --- ```kotlin /* * Copyright © 2020-2026 PSPDFKit GmbH. All rights reserved. * * The PSPDFKit Sample applications are licensed with a modified BSD license. * Please see License for details. This notice may not be removed from this file. */ package com.pspdfkit.catalog.examples.kotlin import android.content.Context import android.net.Uri import android.os.Bundle import android.view.Menu import android.view.MenuItem import androidx.annotation.UiThread import androidx.lifecycle.lifecycleScope import com.pspdfkit.annotations.AnnotationType import com.pspdfkit.bookmarks.Bookmark import com.pspdfkit.catalog.R import com.pspdfkit.catalog.SdkExample import com.pspdfkit.catalog.tasks.ExtractAssetTask.extract import com.pspdfkit.configuration.activity.PdfActivityConfiguration import com.pspdfkit.configuration.page.PageLayoutMode import com.pspdfkit.configuration.sharing.ShareFeatures import com.pspdfkit.document.PdfDocument import com.pspdfkit.preferences.PSPDFKitPreferences import com.pspdfkit.ui.DocumentDescriptor import com.pspdfkit.ui.PdfActivity import com.pspdfkit.ui.PdfActivityIntentBuilder import com.pspdfkit.ui.special_mode.controller.AnnotationTool import com.pspdfkit.utils.getSupportParcelableExtra import kotlinx.coroutines.Dispatchers import kotlinx.coroutines.Job import kotlinx.coroutines.launch import kotlinx.coroutines.withContext import java.util.EnumSet /** * This example shows how to swap between documents and sync view state, annotations, and bookmarks. */ class ELearningExample(context: Context) : SdkExample(context, R.string.eLearningExampleTitle, R.string.eLearningExampleDescription) { override fun launchExample(context: Context, configuration: PdfActivityConfiguration.Builder) { // We'll disable redaction tool in annotation creation toolbar to prevent creation of redaction annotations. val annotationTools = mutableListOf(*AnnotationTool.values()) annotationTools.remove(AnnotationTool.REDACTION) configuration // Turn off saving, so we have the clean original document every time the example is launched..autosaveEnabled(false) // Use single page mode..layoutMode(PageLayoutMode.SINGLE) // Disable all the menu items but annotations editing and bookmark list..outlineEnabled(false).documentInfoViewEnabled(false).annotationListEnabled(false).searchEnabled(false).settingsMenuEnabled(false).setEnabledShareFeatures(EnumSet.noneOf(ShareFeatures::class.java)).printingEnabled(false).thumbnailGridEnabled(false).setRedactionUiEnabled(false).enabledAnnotationTools(annotationTools) // The annotation creator written into newly created annotations. If not set, or set to null // a dialog will normally be shown when creating an annotation, asking you to enter a name. // We are going to skip this part and set it as "John Doe" only if it was not yet set. if (!PSPDFKitPreferences.get(context).isAnnotationCreatorSet) { PSPDFKitPreferences.get(context).setAnnotationCreator("John Doe") } // Extracts the documents from the assets and loads the teacher version first. extract("Teacher.pdf", title, context) { teacherDocumentFile -> extract("Student.pdf", title, context) { studentDocumentFile -> val teacherDocumentUri = Uri.fromFile(teacherDocumentFile) val studentDocumentUri = Uri.fromFile(studentDocumentFile) val intent = PdfActivityIntentBuilder.fromUri(context, teacherDocumentUri).configuration(configuration.build()).activityClass(ELearningActivity::class).build() intent.putExtra(ELearningActivity.STUDENT_URI_KEY, studentDocumentUri) intent.putExtra(ELearningActivity.TEACHER_URI_KEY, teacherDocumentUri) context.startActivity(intent) } } } } class ELearningActivity : PdfActivity() { /** List of annotations in instant JSON format that will be copied over the new document. */ private val serializedAnnotationsToTransfer: MutableList = mutableListOf() /** List of bookmarks that will be copied over the new document. */ private val bookmarksToTransfer: MutableList = mutableListOf() /** Student document URI. */ private lateinit var studentUri: Uri /** Teacher document URI. */ private lateinit var teacherUri: Uri /** Job in charge of switching the document. */ private var switchDocumentJob: Job? = null /** Job in charge of loading the annotation to the new document. */ private var transferDataJob: Job? = null /** Fragment state containing current page, zoom, and scroll. */ private var fragmentState: Bundle? = null /** Flag to keep track of visibility of bookmark list view. */ private var isBookmarkListDisplayed: Boolean = false /** * Create a button to switch between teacher and student documents. */ override fun onCreateOptionsMenu(menu: Menu): Boolean { super.onCreateOptionsMenu(menu) if (document == null || serializedAnnotationsToTransfer.isNotEmpty()) { return false } // Add a new switch button. val switchItem = menu.add(0, SWITCH_ITEM_ID, 0, "Switch") switchItem.setShowAsAction(MenuItem.SHOW_AS_ACTION_IF_ROOM or MenuItem.SHOW_AS_ACTION_WITH_TEXT) return true } /** * Set the corresponding action for every button. */ override fun onOptionsItemSelected(item: MenuItem): Boolean = when (item.itemId) { SWITCH_ITEM_ID -> { switchDocument() true } else -> { super.onOptionsItemSelected(item) } } override fun onPause() { switchDocumentJob?.cancel() transferDataJob?.cancel() super.onPause() } override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) intent.getSupportParcelableExtra(STUDENT_URI_KEY, Uri::class.java)?.let { studentUri = it } intent.getSupportParcelableExtra(TEACHER_URI_KEY, Uri::class.java)?.let { teacherUri = it } } @UiThread override fun onDocumentLoaded(document: PdfDocument) { // Take any serialized annotations that were stored upon switching, and add them to the loaded document. transferDataJob = lifecycleScope.launch { withContext(Dispatchers.IO) { // Create annotations from instant JSON and add them to the document. for (json in serializedAnnotationsToTransfer) { document.annotationProvider.createAnnotationFromInstantJson(json) } // Once all annotations are transferred, we can clear the list. serializedAnnotationsToTransfer.clear() // Take any bookmarks that were stored upon switching, and add them to the loaded document. bookmarksToTransfer.forEach { bookmark -> document.bookmarkProvider.addBookmarkAsync(bookmark).blockingAwait() } // Once all bookmarks are transferred, we can clear the list. bookmarksToTransfer.clear() } // Restore page index, scroll and zoom. fragmentState?.let { requirePdfFragment().state = it fragmentState = null } // Make sure the outline view shows the changes from transferring bookmarks and annotations. pspdfKitViews.outlineView?.setDocument(document, configuration.configuration) // Restore bookmark list view visibility. if (isBookmarkListDisplayed) { pspdfKitViews.outlineView?.show() } invalidateOptionsMenu() } } /** * Switch the document when the button is tapped. This works in multiple steps: * - Fetching all annotations asynchronously, and convert them to Instant JSON format. * - Fetch all bookmarks. * - Save the view state. */ private fun switchDocument() { val document = document?: return // While the document switching is in progress, we disable all document interaction to // prevent changes to be made. requirePdfFragment().isDocumentInteractionEnabled = false // Run the collection of annotations and bookmarks asynchronously. switchDocumentJob = lifecycleScope.launch { // Clear previous data serializedAnnotationsToTransfer.clear() bookmarksToTransfer.clear() withContext(Dispatchers.IO) { // Fetch all annotations, serialize them, and collect them in a list. We keep them around in // memory, and will add them to the other document once it is loaded. val annotations = document.annotationProvider.getAllAnnotationsOfType( AnnotationType.entries.toSet(), ) annotations.forEach { annotation -> val json = annotation.toInstantJson() // For some unsupported annotation types (like popup annotations) we don't offer serialization. // In these cases, `toInstantJson()` returns "null". We filter those from the serialized items. if (invalidInstantJson(json)) { serializedAnnotationsToTransfer.add(json) } } // Fetch the bookmarks for synchronization and collect them in a list. val bookmarks = document.bookmarkProvider.bookmarks bookmarksToTransfer.addAll(bookmarks) } // Save current page index, scroll and zoom. fragmentState = requirePdfFragment().state // Save bookmark list view visibility. isBookmarkListDisplayed = pspdfKitViews.outlineView?.isDisplayed?: false // Swap out the current document to either the teacher or student version. if (document.documentSource.fileUri == teacherUri) { documentCoordinator.setDocument(DocumentDescriptor.fromUri(studentUri)) } else { documentCoordinator.setDocument(DocumentDescriptor.fromUri(teacherUri)) } invalidateOptionsMenu() } } companion object { private const val SWITCH_ITEM_ID = 1234 const val STUDENT_URI_KEY = "TeacherStudentActivity.STUDENT_URI_KEY" const val TEACHER_URI_KEY = "TeacherStudentActivity.TEACHER_URI_KEY" } } private fun invalidInstantJson(it: String) = it!= "null" ``` This code sample is an example that illustrates how to use our SDK. Please adapt it to your specific use case. --- ## Related pages - [Application Policy](/guides/android/samples/application-policy-kotlin.md) - [Custom Form Highlight Color](/guides/android/samples/custom-form-highlight-color-java.md) - [Custom Page Templates](/guides/android/samples/custom-page-templates-java.md) - [Digital Signature (Basic)](/guides/android/samples/digital-signature-basic-kotlin.md) - [Disabled Annotation Property](/guides/android/samples/disabled-annotation-property-java.md) - [Image Document](/guides/android/samples/image-document-kotlin.md) - [Compose Image Document](/guides/android/samples/compose-image-document-kotlin.md) - [Inline Multimedia](/guides/android/samples/inline-multimedia-kotlin.md) - [JavaScript Form Filling](/guides/android/samples/javascript-form-filling-kotlin.md) - [Overlay Visibility](/guides/android/samples/overlay-visibility-kotlin.md) - [PdfFragment](/guides/android/samples/pdffragment-kotlin.md) - [Reader View](/guides/android/samples/reader-view-kotlin.md) - 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