1)Variable Code: package com.example.operator fun main() { var name:String name= "John" name= "Roma" val rollno:Int rollno= 12 println (name) println (rollno) } data class Demo( val name :String= "N/A" ) Output: 2)Operator Arithmetic operation package com.example.operator fun main() { var x = 200 var y = 100 var sum = x + y println (sum) } data class Demo( val name :String= "N/A" ) Output: 3)Function package com.example.operator fun main(args: Array<String>){ result () print ( "Result after subtraction" ) } fun result(){ var num1 = 1700 var num2 = 68 println ( "result = " +(num1 - num2)) } data class Demo( val name :String= "N/A" ) Output: If - else program package com. example.operator fun main(args: Array<String>) { val num1 = 90 val num2 = 100 val result = if (num1 > num2) { " $ num1 is greater than $ num2 " } else { " $ num1 is smaller than $ num2 " } println (result) } data class Demo( val name :String= "N/A" ) Ouput: Kotlin Loop program Code: - package com.example.operator fun main() { val nums = arrayOf ( 1 , 5 , 10 , 15 , 20 ) for (x in nums) { println (x) } } data class Demo( val name :String= "N/A" ) Output: Kotlin when program Code: package com.example.operator fun main() { val day = 4 val result = when (day) { 1 - > "Monday" 2 - > "Tuesday" 3 - > "Wednesday" 4 - > "Thursday" 5 - > "Friday" 6 - > "Saturday" 7 - > "Sunday" else - > "Invalid day." } println (result) } data class Demo( val name :String= "N/A" ) Output: Hello world program. Activitymai n.xml < RelativeLayout xmlns: android ="http://schemas.android.com/apk/res/android" xmlns: app ="http://schemas.android.com/apk/res - auto" xmlns: tools ="http://schemas.android.com/tools" android :layout_width ="match_parent" android :layout_height ="match_parent" > < TextView android :layout_width ="wrap_content" android :layout_height ="wrap_content" android :layout_alignParentStart ="true" android :layout_alignParentTop ="true" android :layout_marginStart ="6dp" android :layout_marginTop ="58dp" android :text ="Hello World!" app :layout_constraintBottom_toBottomOf ="parent" app :layout_constraintEnd_toEndOf ="parent" app :layout_constraintStart_toStartOf ="parent" app :layout_constraintTop_to TopOf ="parent" /> </ RelativeLayout > MainActivity.kt package com.example.helloworld import androidx.appcompat.app.AppCompatActivity import android.os.Bundle class MainActivity : AppCompatActivity() { override fun onCreate( savedInstanceState: Bundle?) { super .onCreate(savedInstanceState) setContentView(R.layout. activity_main ) } } AndroidManifest.xml <? xml version ="1.0" encoding ="utf - 8" ?> < manifest xmlns: android ="http://schemas.android.com/apk /res/android" xmlns: tools ="http://schemas.android.com/tools" > < application android :allowBackup ="true" android :icon ="@mipmap/ic_launcher" android :label ="@string/app_name" android :supportsRtl ="true" android :th eme ="@style/Theme.Helloworld" tools :targetApi ="31" > < activity android :name =".MainActivity" android :exported ="true" > < intent - filter > < action android :name ="android.intent.action.MAIN" /> < category android :name ="android.intent.category.LAUNCHER" /> </ intent - filter > </ activity > </ application > </ manifest > String.xml file < resources > < string name ="app_name" >Hello world program</ string > < string name ="hello_world" >Hello world!!!</ string > < string name ="menu_settings" >Setting</ string > < string name ="title_activity_main" >MainActivity</ string > </ resources > Output: Text view pro gram A ctivitymain.xml file <?xml version=“1.0” encoding=“utf - 8”?> <LinearLayout xmlns:android=“http://schemas.android.com/apk/res/android” xmlns:tools=“http://schemas.android.com/tools” android:orientation=“vertical” android:layout_width=“match_parent” android:layout_height=“match_parent” tools:context=“.MainActivity”> <! — EditText with id editText <TextView android:id=“@+id/text_view_id” android:layout_height=“wrap_content” android:layout_width=“wrap_content” android:text=“@string/text_view” android:textColor=“#008000” android:textSize=“40dp” android:textStyle=“bold”/> </LinearLayout> Main Actiuvity.kt package com.example.sycspractical2ic import 25ndroid.appcompat.app.AppCompatActivity import android.os.Bundle import android. widget.TextView import android.widget.Toast class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) //accessing our 25ndroid25 from layout val textView = findViewById<TextView>(R.id.text_view_id) textView.setOnClickListener{ Toast.makeText(this@MainActivity, R.string.text_on_click, Toast.LENGTH_LONG).show() } } } String .xml file <resources> <string name=“app_name”>SYCSPractical2ic</string> <string name=“text_view”>www. bkbirla .com</string> <string name=“text_on_click”>COMPUTER SCIENCE PORTAL</string> </resources> AndroidM anifest.xml file <?xml version=“1.0” encoding=“utf - 8”?> <manifest xmln s:android=“http://schemas.android.com/apk/res/android” xmlns:tools=“http://schemas.android.com/tools”> <application android:allowBackup=“true” android:dataExtractionRules=“@xml/data_extraction_rules” android:fullBackupContent=“@xml/backup_rules” andr oid:icon=“@mipmap/ic_launcher” android:label=“@string/app_name” android:supportsRtl=“true” android:theme=“@style/Theme.SYCSPractical2ic” tools:targetApi=“31”> <activity android:name=“.MainActivity” android:exported=“true”> <intent - filter> <action android:name=“android.intent.action.MAIN” /> <category android:name=“android.intent.category.LAUNCHER” /> </intent - filter> </activity> </application> </manifest> Output: EditT ext Program Acti vityMain.x ml file <?xml version="1.0" encoding= "utf - 8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=". MainActivity"> <! -- EditText with id editText -- > <EditText android:id="@+id/editText" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_margin="16dp" android:hint="Input" android:inputType="text"/> <Button and roid:id="@+id/showInput" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center_horizontal" android:text="show" android:backgroundTint="@color/colorPrimary" android:textColor="@android:color/white" /> </LinearLayout> MainActivity.kt file package com.example.sycspractical2ib import android.annotation.SuppressLint import android.os.Bundle import android.support.v7.app.AppCompatActivity import android.widget.Button import android.wi dget.EditText import android.widget.Toast import com.example.sycspractical2aii.R class MainActivity : AppCompatActivity() { @SuppressLint("MissingInflatedId") override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setCo ntentView(R.layout.activity_main) // finding the button val showButton = findViewById<Button>(R.id.showInput) // finding the edit text val editText = findViewById<EditText>(R.id.editText) // Setting On Click Listener showButton.setOnClickListener { // Getting the user input val text = editText.text Output Button program Activi ty Main.xml file <?xml version=“1.0” encoding=“utf - 8”?> <! — suppress ALL <39ndroid.constraintlayout.widget.ConstraintLayout xmlns:android=“http://schemas.android.com/apk/res/android” xmlns:app=“http://schemas.android.com/apk/res - auto” xmlns:tools=“http://schemas.android.com/tools” android:layout_width=“match_parent” android:layout_height=“match_parent” android:background=“#168BC34A” tools:context=“.MainActivity” tools:ignore=“MissingClass”> <! — Button added in the activity <Button android:id=“@+id/button” android:layout_width=“wrap_content” android:layout_height=“wrap_content” android:background=“#4CAF50” android:paddingStar t=“10dp” android:paddingEnd=“10dp” app:layout_constraintEnd_toEndOf=“parent” app:layout_constraintStart_toStartOf=“parent” app:layout_constraintTop_toTopOf=“parent” /> String.xml file <resources> <string name=“app_name”>SYCSPractical2iic</string> < string name=“btn”>Button</string> <string name=“message”>Hello Geeks!! This is a Button.</string> </resources> Output: Implicit program Acti vityMain.xml fil e <?xml version="1.0" encoding="utf - 8"?> <! -- suppress ALL -- > <androidx.constraintlayout.widget.ConstraintLayou t xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res - auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".Mai nActivity"> <EditText android:id="@+id/editText" android:layout_width="match_parent" android:layout_height="wrap_content" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" /> <Button android:id="@+id/btn" android:text="Search" android:onClick="search" android:layout_width="wrap_content" a ndroid:layout_height="wrap_content" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/editText" /> </androidx.constraintlayo ut.widget.ConstraintLayout> Mai nActi vity.kt file package com.example.sycspractical4i import android.content.Intent import android.net.Uri import android.os.Bundle import android.support.v7.app.AppCompatActivity import android.widget.EditText class MainActivity : AppCompatActi vity() { lateinit var editText: EditText override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) editText = findViewById(R.id.editText) } fun search() { val url = editText.text. toString() val urlIntent = Intent(Intent.ACTION_VIEW, Uri.parse(url)) startActivity(urlIntent) } } Output Explicit intent ActvityMain.xml fil e <?xml version ="1.0" encoding="utf - 8"?> <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res - auto" xmlns:tools="http://schemas.android.com/tools" android:layout_wi dth="match_parent" android:layout_height="match_parent" tools:context="com.example.explicitintentexample.MainActivity"> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" android:grav ity="center"> <Button android:id="@+id/button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Launch Second Activity"/> </LinearLayout> </androidx.constraintlayout.widget.ConstraintLayout> MainActvity .kt file package com.example.explicitintentexample import android.content.Intent import androidx.appcompat.app.AppCompatActivity import android.os.Bundle import android.widget.Button class MainActivity : AppCompat Activity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) val button = findViewById<Button>(R.id.button) button.setOnClickListener { val intent = Intent(this, SecondActi vity::class.java) startActivity(intent) } } } Output: