Guide to Install and Setup IntelliJ IDEA for Android App Development

IntelliJ IDEA is a robust IDE developed by JetBrains, and while it's primarily recognized for Java development, it can be configured for Android app development. Here's how to install and set it up for Android development:

1. System Requirements:

Make sure your system meets the minimum requirements for IntelliJ IDEA. The requirements can be found on the official JetBrains website.

2. Download IntelliJ IDEA:

Go to the official IntelliJ IDEA download page and download the appropriate edition. For Android development, the Ultimate edition is recommended because of its extended features. However, you can still work with the Community edition.

3. Installation:

Windows: Run the downloaded .exe file and follow the setup instructions.
Mac: Open the downloaded .dmg file and drag the IntelliJ IDEA app to the Applications folder.
Linux: Unpack the downloaded .tar.gz file to a desired directory and run the idea.sh script in the bin subdirectory.

4. Setup IntelliJ IDEA:

Upon first launch, the setup wizard will guide you through:

Import Settings: If you have a previous version of IntelliJ IDEA, you can import settings from it. Otherwise, choose the Do not import settings option.
UI Theme: Choose between a light or dark theme.
Keymaps: You can select a keyboard scheme that you're familiar with.
Plugins: At this stage, ensure you enable the Android support plugin.

5. Configuring the SDK:

Before developing Android apps, you need to configure the Android SDK:

Open IntelliJ IDEA and click on Configure > SDK Manager at the bottom right.
In the SDK Platforms tab, select the versions of Android you want to develop for and install them.
In the SDK Tools tab, ensure that you've installed:
- Android SDK Build-Tools
- Android SDK Platform-Tools
- Android SDK Tools
- Android Emulator (if you want to use it)
- Android NDK (if you'll be doing native/C++ development)

6. Start Android Development:

Once the SDK is set up:

Click on File > New > Project.
Select Android on the left pane.
Choose Empty Activity or another template depending on your needs.
Fill in your application name, package name, and other initial configurations.
Click Finish.

Now, IntelliJ IDEA will create an Android project for you with a basic structure.

7. Emulator:

If you installed the Android Emulator during the SDK setup:

Click on Tools > AVD Manager.
Create a new Virtual Device or use an existing one.

Note:

While IntelliJ IDEA is a fantastic IDE for Java and Kotlin development, many Android developers prefer Android Studio for app development because it's tailored specifically for Android and frequently updated with the latest Android-centric features. Android Studio is built on the IntelliJ IDEA platform, so many features are similar, but it's optimized for Android development. If you're exclusively focusing on Android development, consider using Android Studio.

Using Gradle for Android projects in IntelliJ IDEA:
- Description: Gradle is the build system used for Android projects. IntelliJ IDEA integrates with Gradle for building, testing, and packaging Android apps. Gradle configurations are specified in the build.gradle files.
- Code:
```
// Sample build.gradle for an Android project
android {
    compileSdkVersion 30
    defaultConfig {
        applicationId "com.example.myapp"
        minSdkVersion 16
        targetSdkVersion 30
    }
}
```
Adding Android dependencies and plugins in IntelliJ IDEA:
- Description: Add dependencies and plugins for Android projects in IntelliJ IDEA by modifying the build.gradle file. Dependencies can include libraries, support libraries, and other Gradle plugins.
- Code:
```
// Add a dependency in build.gradle
dependencies {
    implementation 'com.android.support:appcompat-v7:30.0.0'
}
```