The Countdown Timer app is a lightweight utility that launches a modal dialog to count down from 10 seconds. Once the timer reaches zero, the app plays a system error tone and closes the dialog. This project serves as a basic example of using CountDownTimer, ToneGenerator, and custom Dialog implementation in Android.

Key Features

Single-Action Interface: A simple main screen with a start button.
Modal Countdown: A non-cancelable dialog that prevents user interference during the countdown.
Audible Alert: Integration with Android's ToneGenerator to play TONE_SUP_ERROR upon completion.
Real-time Updates: UI updates every second to reflect the remaining time.

Getting Started

Prerequisites

Android Studio (Ladybug or newer recommended)
JDK 17
An Android device or emulator running API level 24 or higher.

Building the App

To build the debug APK from the command line:

./gradlew assembleDebug

Running the App

Open the project in Android Studio.
Select your target device/emulator.
Click the Run button or press Shift + F10.

Project Structure

app/
├── src/
│   └── main/
│       ├── java/com/example/countdowntimer/
│       │   ├── MainActivity.kt      # Main entry point; launches the timer
│       │   └── CountdownDialog.kt   # Logic for the 10s countdown and tone
│       ├── res/                     # UI layouts and resources
│       └── AndroidManifest.xml      # Application manifest
└── build.gradle                     # App-level build configuration