Hello Readers! In this post, we are going to learn about how to use android floating action button programmatically in kotlin in the application. We will also learn how to add floating action button to linearLayout programmatically in android application.

Output

Dynamic Floating Action Button Output

Getting Started

At first, we will create android project. Then, we will create and use floating action button programmatically in kotlin file.

1. Creating New Project in Kotlin

Follow the steps below to create new project. Please ignore the steps if you have already created a new project.

Now, we will modify xml and kotlin file to use floating action button dynamically.

2. Modify Values Folder

Open res/values/strings.xml file. Then, add below code into it.

<resources>
	<string name="app_name">DynamicFloatingActionButton</string>
	<string name="message">Floating Action Button has been created dynamically. Click on it to see Toast message.</string>
</resources>

Now, open res/values/styles.xml file and add below code into it.

<resources>

	<!-- Base application theme. -->
	<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
		<!-- Customize your theme here. -->
		<item name="colorPrimary">@color/colorPrimary</item>
		<item name="colorPrimaryDark">@color/colorPrimaryDark</item>
		<item name="colorAccent">@color/colorAccent</item>
	</style>

	<style name="AppTheme.AppBarOverlay" parent="AppTheme">
	</style>

	<style name="AppTheme.PopupOverlay" parent="AppTheme">
	</style>

</resources>

3. Define main content xml file

Now, we will add an xml file that will contains main UI for the application. So, create an xml file, named content_main.xml, in res/layout/content_main.xml. Then, add below code into it.

<?xml version="1.0" encoding="utf-8"?>
<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"
	app:layout_behavior="@string/appbar_scrolling_view_behavior"
	tools:showIn="@layout/activity_main">

	<TextView
		android:layout_width="wrap_content"
		android:layout_height="wrap_content"
		android:layout_centerInParent="true"
		android:layout_margin="40dp"
		android:text="@string/message"/>

</RelativeLayout>

Note – This is optional step. You may not need to add this file based on your application structures.

4. Modify Layout Folder

Open res/layout/activity_main.xml file. Then, add below code into it.

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
	xmlns:android="http://schemas.android.com/apk/res/android"
	xmlns:app="http://schemas.android.com/apk/res-auto"
	android:layout_width="match_parent"
	android:layout_height="match_parent"
	android:fitsSystemWindows="true">

	<android.support.design.widget.AppBarLayout
		android:layout_width="match_parent"
		android:layout_height="wrap_content"
		android:theme="@style/AppTheme.AppBarOverlay">

		<android.support.v7.widget.Toolbar
			android:id="@+id/toolbar"
			android:layout_width="match_parent"
			android:layout_height="?android:attr/actionBarSize"
			android:background="@color/colorPrimary"
			app:popupTheme="@style/AppTheme.PopupOverlay"
			app:titleTextColor="@android:color/white"/>

	</android.support.design.widget.AppBarLayout>

	<include layout="@layout/content_main"/>

	<LinearLayout
		android:id="@+id/rootContainer"
		android:layout_width="wrap_content"
		android:layout_height="wrap_content"
		android:layout_gravity="bottom|end"
		android:orientation="vertical">

	</LinearLayout>

</android.support.design.widget.CoordinatorLayout>

5. Create Android Floating Action Button Programmatically / Dynamically in Kotlin

Open app/src/main/java/com.tutorialwing.dynamicfloatingactionbutton/MainActivity.kt file. Then, add below code into it.

package com.tutorialwing.dynamicfloatingactionbutton

import android.os.Bundle
import android.support.design.widget.FloatingActionButton
import android.support.v7.app.AppCompatActivity
import android.support.v7.widget.Toolbar
import android.view.ViewGroup
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 toolbar = findViewById<Toolbar>(R.id.toolbar)
        setSupportActionBar(toolbar)

        val floatingActionButton = FloatingActionButton(this)

        val layoutParams = LinearLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT)
        layoutParams.setMargins(32, 32, 32, 32)
        floatingActionButton.layoutParams = layoutParams
        floatingActionButton.setImageResource(android.R.drawable.ic_dialog_email)
        floatingActionButton.setOnClickListener {
            // We are showing only toast message. However, you can do anything you need.
            Toast.makeText(applicationContext, "You clicked Floating Action Button", Toast.LENGTH_SHORT).show()
        }

        val linearLayout = findViewById<LinearLayout>(R.id.rootContainer)
        linearLayout?.addView(floatingActionButton)
    }
}

Since AndroidManifest.xml file is very important in any android application, we are also going to see the content inside this file.

AndroidManifest.xml file

Code inside src/main/AndroidManifest.xml file is –

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

	<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>

When we run the program, we will get output as shown above.

That’s end of our tutorial on Creating Android Floating Action Button Programmatically in Kotlin.