Android Wrapper for Streamlit Applications

This project is a lightweight Android wrapper for running any public Streamlit app inside a native Android WebView.

It allows you to:

• Wrap your Streamlit app in an Android interface
• Generate an .apk or .aab
• Publish it to the Google Play Store

📱 Ideal for data scientists, developers, educators or researchers who want to make their web-based apps available as native Android apps — without rewriting them in Java/Kotlin.

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✅ Features

• Minimal native code (just a WebView)
• Compatible with Streamlit’s full interactivity
• Supports file uploads, plots, input widgets, etc.
• Works on Android 5.0+ (minSdk 21)
• Small app size (~5 MB)

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🚀 How to Use

1. Clone the repo

git clone https://github.com/luiscunhacsc/androidwrapper4streamlit.git
cd androidwrapper4streamlit

2. Open in Android Studio

• Launch Android Studio
• Open the project directory
• Let it sync Gradle files

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🔄 Customize the App

3. Set your Streamlit app URL

Open MainActivity.java and set your URL:

private String streamlitUrl = "https://yourusername-yourappname.streamlit.app";

Ensure the URL is publicly accessible.

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4. Rename the Package

To be accepted on Google Play, you must use a unique package name — never use com.example.

Update the following to your own reverse domain name:

Example:

package com.joanasilva.myfinanceapp;

Update the same in:

• build.gradle:

  namespace 'com.joanasilva.myfinanceapp'
  applicationId "com.joanasilva.myfinanceapp"

• Rename folder structure:

  app/src/main/java/com/joanasilva/myfinanceapp/MainActivity.java
  

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❗ Common issue: “Cannot resolve symbol R”

This is caused by a mismatch in package names or errors in res files.

How to fix:

1. Match package name everywhere (MainActivity, build.gradle, folder)
2. File > Sync Project with Gradle Files
3. Build > Clean Project, then Build > Rebuild
4. Check for errors in XML files (e.g., activity_main.xml)
5. If needed: File > Invalidate Caches / Restart

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📦 Generate the App Bundle (.aab)

Google Play requires .aab files for new apps.

In Android Studio:

Build > Build Bundle(s) / APK(s) > Build Bundle (AAB)

Output is in:

app/build/outputs/bundle/release/app-release.aab

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🛡️ Google Play Store Requirements

To publish your app, the Play Console requires:

Requirement	Description	Suggestions
✅ Unique package name	Must not be com.example	Use a reverse domain: com.nome.aplicacao
📸 Screenshots	At least 2 screenshots (1080x1920)	Use Android Emulator + Shift+Cmd+S or `Screenly
🖼️ App icon	512x512 PNG	Use Canva or IconKitchen
📜 Privacy policy URL	Public link is required	Use Notion, Google Docs, or GitHub Pages
📋 Content Rating	Fill in Google's questionnaire	Done inside Play Console
🌍 Countries & Pricing	Choose target countries	Usually set as “Free”
🔒 Data safety form	Describe data collection (usually none)	Mark as: no data collected, no shared data
📲 Target API level	Must be recent (e.g. 34)	Already set in build.gradle

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🧠 Tips for Better Mobile Experience

• In your Streamlit app, add:

st.set_page_config(layout="wide")

• Use st.button, st.radio, st.selectbox, etc., instead of complex drag/drop widgets
• Keep pages light to reduce load time on mobile networks

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📄 License

MIT License — feel free to use and adapt.

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🙌 Credits

Created by Luís Cunha to make Streamlit apps more accessible via the Android ecosystem.