> For the complete documentation index, see [llms.txt](https://docs.apryse.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.apryse.com/android/viewer/new-ui-migration.md).

# Migrate to the New Viewer UI

Learn how to easily migrate to the new UI for your document viewer in your app with just a few simple steps. Update to version 7.1.5 of Apryse libraries, switch to ViewerBuilder2, and make necessary r

If you have integrated the document viewer previously in your app (i.e. [`DocumentActivity`](/android/open-save-document/open.md) or [`PdfViewCtrlTabHostFragment`](/android/open-save-document/open.md)), you can easily migrate to use the new UI with a couple of simple steps.

## Prerequisites

* Updated Apryse libraries to version 7.1.5 (see [changelog](/android/changelogs/version-7/v7-1-5.md) for more info)

## Migrate PdfViewCtrlTabHostFragment

1. Update all references to `ViewerBuilder` to `ViewerBuilder2`. This new builder will create the new viewer fragment [`PdfViewCtrlTabHostFragment2`](https://sdk.apryse.com/api/android/javadoc/reference/com/pdftron/pdf/controls/PdfViewCtrlTabHostFragment2.html), which contains the new UI.
2. Update all references to `PdfViewCtrlTabHostFragment` to `PdfViewCtrlTabHostFragment2` in your project.
3. Update all references to `PdfViewCtrlTabFragment` to [`PdfViewCtrlTabFragment2`](https://sdk.apryse.com/api/android/javadoc/reference/com/pdftron/pdf/controls/PdfViewCtrlTabFragment2.html) in your project.
4. (Optional) If you have defined the `CustomAppTheme` style to customize your theme, you will need to change this style to extend `PDFTronAppTheme` and pass it into `ViewerBuilder2` as described in our customize viewer theme guide.

## Migrate DocumentActivity

1. Remove any calls to `DocumentActivity.openDocument(...)`.
2. Then launch the activity using `DocumentActivity.IntentBuilder` as described in this guide.
3. If you have defined the `CustomAppTheme` style to customize your theme, you will need to change this style to extend `PDFTronAppTheme`.


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