kotlin android app development course, setting permissions

Setting permissions in Android application development is a very important aspect. Permissions mean the rights that an application requests from the user to use specific features or data, and proper permission settings contribute to improving user experience and enhancing security. In this course, we will explore how to set permissions in Android applications using Kotlin in detail.

1. Understanding Permissions

In Android, permissions must be requested when using various functions such as network access, camera, and location information. These permissions may be required at the time the user installs the app or requested at runtime when specific features are used. Permissions can be broadly classified into two categories:

• Static Permissions: Declared in the application’s AndroidManifest.xml file and approved by the user upon installation.
• Dynamic Permissions: A concept introduced after Marshmallow (Android 6.0, API 23), which are requested from the user at runtime.

2. Setting Permissions in AndroidManifest.xml

Static permissions are declared in the application’s AndroidManifest.xml file. For example, to set camera access permission, the following code should be added.

<uses-permission android:name="android.permission.CAMERA"/>

The above code is essential for apps that use the camera. It is advisable to clearly state all required permissions and explain the permissions requested from the user.

3. Requesting Dynamic Permissions

Dynamic permissions are requested from the system while the application is running. Below, we will look at how to request permissions for the camera and location information.

3.1 Installing Permission Request Library

To handle permission requests more easily, you can use the ActivityCompat and ContextCompat classes provided by Android. These classes provide various methods related to permission requests. Now, let’s go through a simple example of requesting dynamic permissions.

3.2 Code Example

The following is the complete code of a simple Android app that requests camera and location information.

import android.Manifest
import android.content.pm.PackageManager
import androidx.appcompat.app.AppCompatActivity
import androidx.core.app.ActivityCompat
import androidx.core.content.ContextCompat
import android.os.Bundle
import android.widget.Button
import android.widget.Toast

class MainActivity : AppCompatActivity() {
    
    private val CAMERA_REQUEST_CODE = 100
    private val LOCATION_REQUEST_CODE = 101
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        
        val buttonCamera = findViewById(R.id.button_camera)
        val buttonLocation = findViewById(R.id.button_location)
        
        buttonCamera.setOnClickListener {
            requestCameraPermission()
        }
        
        buttonLocation.setOnClickListener {
            requestLocationPermission()
        }
    }
    
    private fun requestCameraPermission() {
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this, arrayOf(Manifest.permission.CAMERA), CAMERA_REQUEST_CODE)
        } else {
            Toast.makeText(this, "Camera permission has already been granted.", Toast.LENGTH_SHORT).show()
        }
    }
    
    private fun requestLocationPermission() {
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this, arrayOf(Manifest.permission.ACCESS_FINE_LOCATION), LOCATION_REQUEST_CODE)
        } else {
            Toast.makeText(this, "Location permission has already been granted.", Toast.LENGTH_SHORT).show()
        }
    }

    override fun onRequestPermissionsResult(requestCode: Int, permissions: Array, grantResults: IntArray) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults)
        when (requestCode) {
            CAMERA_REQUEST_CODE -> {
                if ((grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED)) {
                    Toast.makeText(this, "Camera permission has been granted.", Toast.LENGTH_SHORT).show()
                } else {
                    Toast.makeText(this, "Camera permission has been denied.", Toast.LENGTH_SHORT).show()
                }
            }
            LOCATION_REQUEST_CODE -> {
                if ((grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED)) {
                    Toast.makeText(this, "Location permission has been granted.", Toast.LENGTH_SHORT).show()
                } else {
                    Toast.makeText(this, "Location permission has been denied.", Toast.LENGTH_SHORT).show()
                }
            }
        }
    }
}

3.3 Code Explanation

The above code requests camera and location information from the user. The requestCameraPermission and requestLocationPermission methods check and request camera and location permissions, respectively. The ActivityCompat.requestPermissions method sends the permission request. The results of this request are handled in the onRequestPermissionsResult method.

4. Precautions When Requesting Permissions

There are several precautions to consider when requesting permissions:

• If a user denies a permission, provide an alternative method. For example, if camera permission is denied, you could provide an option to choose a photo instead of using the camera.
• Clearly explain the purpose of the permission to the user to encourage them to grant the permission. For example, it is advisable to add descriptions like “Needed for providing location-based services” when requesting location permission.
• Not all apps need all permissions. Requesting unnecessary permissions can cause undue inconvenience to users, so it is preferable to request only the permissions that are absolutely necessary.

5. Conclusion

Permission settings are a crucial part of Android applications, essential for protecting users’ personal information and effectively utilizing the application’s features. This course covered how to set permissions using Kotlin. By requesting the necessary permissions from users, enhance the functionality of your application.

We will continue to cover Android development related content in the future. In the next course, we will delve deeper into user interface design, so please stay tuned!