How to turn Android device screen on and off programmatically using Kotlin?

This example demonstrates how to turn an Android device screen on and off programmatically using Kotlin.

Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.

Step 2 − Add the following code to res/layout/activity_main.xml.

<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:layout_margin="8dp">    <TextView       android:id="@+id/textView"       android:layout_width="wrap_content"       android:layout_height="wrap_content"       android:layout_centerHorizontal="true"       android:layout_marginTop="70dp"       android:background="#008080"       android:padding="5dp"       android:text="TutorialsPoint"       android:textColor="#fff"       android:textSize="24sp"       android:textStyle="bold" />    <LinearLayout       android:layout_width="match_parent"       android:layout_height="wrap_content"       android:layout_centerInParent="true"       android:orientation="horizontal">    <Button       android:id="@+id/btnEnable"       android:layout_width="0dp"       android:layout_height="wrap_content"       android:layout_weight="1"       android:onClick="enablePhone"       android:text="Enable" />    <Button       android:id="@+id/btnLock"       android:layout_width="0dp"       android:layout_height="wrap_content"       android:layout_weight="1"       android:onClick="lockPhone"       android:text="Lock" />    </LinearLayout> </RelativeLayout>

Step 3 − Add the following code to src/MainActivity.kt

import android.app.admin.DevicePolicyManager import android.content.ComponentName import android.content.Context import android.content.Intent import android.os.Bundle import android.view.View import android.widget.Button import android.widget.Toast import androidx.annotation.Nullable import androidx.appcompat.app.AppCompatActivity class MainActivity : AppCompatActivity() {    private val enableResult = 1    lateinit var deviceManger: DevicePolicyManager    lateinit var compName: ComponentName    lateinit var btnEnable: Button    lateinit var btnLock: Button    override fun onCreate(savedInstanceState: Bundle?) {       super.onCreate(savedInstanceState)       setContentView(R.layout.activity_main)       title = "KotlinApp"       btnEnable = findViewById(R.id.btnEnable)       btnLock = findViewById(R.id.btnLock)       deviceManger = getSystemService(Context.DEVICE_POLICY_SERVICE) as DevicePolicyManager       compName = ComponentName(this, DeviceAdmin::class.java)       val active = deviceManger.isAdminActive(compName)       if (active) {          btnEnable.text = "Disable"          btnLock.visibility = View.VISIBLE       }       else {          btnEnable.text = "Enable"          btnLock.visibility = View.GONE       }    }    fun enablePhone(view: View) {       val active = deviceManger.isAdminActive(compName)       if (active) {          deviceManger.removeActiveAdmin(compName)          btnEnable.text = "Enable"          btnLock.visibility = View.GONE       }       else {          val intent = Intent(DevicePolicyManager.ACTION_ADD_DEVICE_ADMIN)          intent.putExtra(DevicePolicyManager.EXTRA_DEVICE_ADMIN, compName)          intent.putExtra(DevicePolicyManager.EXTRA_ADD_EXPLANATION, "You should enable the app!")          startActivityForResult(intent, enableResult)       }    }    fun lockPhone(view: View) {       deviceManger.lockNow()    }    override fun onActivityResult(requestCode: Int, resultCode: Int, @Nullable data: Intent?) {       super.onActivityResult(requestCode, resultCode, data)       when (requestCode) {          enableResult -> {             if (resultCode == RESULT_OK) {                btnEnable.text = "Disable"                btnLock.visibility = View.VISIBLE             }             else {                Toast.makeText(                applicationContext, "Failed!",                Toast.LENGTH_SHORT             ).show()          }          return       }    } } }

Step 4 − Create a new Kotlin class (DeviceAdmin.kt) and add the following code −

import android.app.admin.DeviceAdminReceiver import android.content.Context import android.content.Intent import android.widget.Toast class DeviceAdmin : DeviceAdminReceiver() {    override fun onEnabled(context: Context, intent: Intent) {       super.onEnabled(context, intent)       Toast.makeText(context, "Enabled", Toast.LENGTH_SHORT).show()    }    override fun onDisabled(context: Context, intent: Intent) {       super.onDisabled(context, intent)       Toast.makeText(context, "Disabled", Toast.LENGTH_SHORT).show()    } }

Step 5 − Add the following code to res/xml/policies.xml

<?xml version="1.0" encoding="utf-8"?> <device-admin xmlns:android="http://schemas.android.com/apk/res/android">    <uses-policies>       <force-lock />    </uses-policies> </device-admin> 

Step 6 − Add the following code to androidManifest.xml

<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="com.example.q2">    <application       android:allowBackup="true"       android:icon="@mipmap/ic_launcher"       android:label="@string/app_name"       android:roundIcon="@mipmap/ic_launcher_round"       android:supportsRtl="true"       android:theme="@style/AppTheme">       <activity android:name=".MainActivity">          <intent-filter>             <action android:name="android.intent.action.MAIN" />             <category android:name="android.intent.category.LAUNCHER" />          </intent-filter>       </activity>       <receiver          android:name=".DeviceAdmin"          android:permission="android.permission.BIND_DEVICE_ADMIN" >       <meta-data          android:name= "android.app.device_admin"          android:resource= "@xml/policies" />       <intent-filter>          <action android:name= "android.app.action.DEVICE_ADMIN_ENABLED" />       </intent-filter>       </receiver>    </application> </manifest>

Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from android studio, open one of your project's activity files and click the Run icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen.