How do I programmatically add buttons into layout one by one in several lines using Kotlin?

This example demonstrates how to programmatically add buttons into layout one by one in several lines 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.

Example

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="https://schemas.android.com/apk/res/android"
   xmlns:tools="https://schemas.android.com/tools"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_gravity="center_horizontal"
   android:orientation="vertical"
   tools:context=".MainActivity">

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

import android.os.Bundle
import android.view.Gravity
import android.widget.Button
import android.widget.LinearLayout
import androidx.appcompat.app.AppCompatActivity
class MainActivity : AppCompatActivity() {
   override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.activity_main)
      title = "KotlinApp"
      val layout = LinearLayout(this)
      layout.orientation = LinearLayout.VERTICAL
      for (i in 0..2) {
         val row = LinearLayout(this)
         row.layoutParams = LinearLayout.LayoutParams(
            LinearLayout.LayoutParams.WRAP_CONTENT,
            LinearLayout.LayoutParams.WRAP_CONTENT
         )
         layout.gravity = Gravity.CENTER
         for (j in 0..3) {
            val btnTag = Button(this)
            btnTag.layoutParams = LinearLayout.LayoutParams(
               LinearLayout.LayoutParams.WRAP_CONTENT,
               LinearLayout.LayoutParams.MATCH_PARENT
            )
            btnTag.text = "Button " + (j + 1 + i * 4)
            btnTag.id = j + 1 + i * 4
            row.addView(btnTag)
         }
         layout.addView(row)
      }
      setContentView(layout)
   }
}

Step 4 − Add the following code to androidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="https://schemas.android.com/apk/res/android" package="com.example.q11">
   <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>
   </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