Permission handling in Android refers to the way in which an app requests and manages access to specific features or data on a device. These permissions help to ensure the security and privacy of the user's device and data.

Android applications require permissions to perform certain actions, such as accessing the device's camera, microphone, or location data. Permissions are granted by the user when the app is installed or when the app requests access to a feature for the first time.

Developers can define the permissions required by their app in the AndroidManifest.xml file. When the user installs an app, they are presented with a list of permissions that the app requires. The user can choose to grant or deny each permission individually.

If an app is denied a permission, it may not be able to function properly or may have limited functionality. In some cases, the app may prompt the user to grant the permission again.

It is important for developers to request only the permissions that are necessary for the app to function. Requesting unnecessary permissions can lead to user distrust and may result in the app being uninstalled.

In conclusion, permission handling is a crucial aspect of Android app development that helps to protect user privacy and security. Developers should carefully consider the permissions required by their app and ensure that they are requesting only what is necessary for the app to function.

Here is a sample code for requesting a camera permission in Kotlin:

// Check if the app has camera permission
if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA)
    != PackageManager.PERMISSION_GRANTED) {

    // Request camera permission
    ActivityCompat.requestPermissions(this,
        arrayOf(Manifest.permission.CAMERA),
        MY_PERMISSIONS_REQUEST_CAMERA)
} else {
    // Permission is already granted
    // Open camera
    val cameraIntent = Intent(MediaStore.ACTION_IMAGE_CAPTURE)
    startActivityForResult(cameraIntent, CAMERA_REQUEST_CODE)
}

// Handle the result of the permission request
override fun onRequestPermissionsResult(requestCode: Int,
    permissions: Array<String>, grantResults: IntArray) {
    when (requestCode) {
        MY_PERMISSIONS_REQUEST_CAMERA -> {
            // If request is cancelled, the result arrays are empty.
            if ((grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED)) {
                // Permission is granted
                // Open camera
                val cameraIntent = Intent(MediaStore.ACTION_IMAGE_CAPTURE)
                startActivityForResult(cameraIntent, CAMERA_REQUEST_CODE)
            } else {
                // Permission is denied
                Toast.makeText(this, "Camera permission denied", Toast.LENGTH_SHORT).show()
            }
            return
        }
    }
}

In this code, we first check if the app has the camera permission. If it does not, we request the permission using ActivityCompat.requestPermissions. Then, we handle the result of the permission request in the onRequestPermissionsResult function. If the permission is granted, we can open the camera using an Intent. If the permission is denied, we show a toast message to the user.