Dynamic Button in Kotlin

In Android, a button represent something that can be clicked by the user to perform some action.
Firstly, we need to create a project in Android Studio. To do follow these steps:

Click on File, then New, and then New Project, and give name whatever you like: 

• Click on File, then New, and then New Project, and give name whatever you like
• Then, select Kotlin language Support and click next button.
• Select minimum SDK, whatever you need.
• Select Empty activity and then click finish.

After doing this you will see some directories on the left hand side after your project/gradle is finished loading. It should look like this: 

Second step is to design our layout page. Go to app > res > layout and paste the following code:

Modify activity_main.xml file

XML

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">

    <LinearLayout
            android:id="@+id/layout"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="center"
            android:orientation="vertical">
    </LinearLayout>

</android.support.constraint.ConstraintLayout>

After setting up the design our final step is to code our progress bar. Open app/src/main/java/yourPackageName/MainActivity.kt 

Create Button in MainActivity.kt file

First of all, we define the button and set its attributes.  

val button = Button(this)
        // setting layout_width and layout_height using layout parameters
        button.layoutParams = LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT,
 ViewGroup.LayoutParams.WRAP_CONTENT)
 

then, add the button in the layout using addView()

       
 val layout = findViewById(R.id.layout) as LinearLayout
 // add Button to LinearLayout
        layout.addView(button)

Java

package com.geeksforgeeks.myfirstkotlinapp

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.ViewGroup
import android.widget.Button
import android.widget.LinearLayout
import android.widget.Toast

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val layout = findViewById(R.id.layout) as LinearLayout

        // creating the button
        val button = Button(this)
        // setting layout_width and layout_height using layout parameters
        button.layoutParams = LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT)
        button.text = "WELCOME TO GFG"
        button.setOnClickListener { Toast.makeText(this@MainActivity, "Hello GEEK", Toast.LENGTH_LONG).show() }


        // add Button to LinearLayout
        layout.addView(button)
    }
}

AndroidManifest.xml file

XML

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
          package="i.apps.button">

    <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>

Run as Emulator: