Introduction
In this blog, you will learn about the Toggle Button widget, which is commonly used in Android applications. Widgets are the elements of the user interface that helps provide a smooth interface for the users. Toggle buttons play the role of an on/off button in our Android application. Toggle buttons are a subclass of Composite Buttons. Some common examples of Toggle buttons include Wifi hotspot buttons, Bluetooth buttons, etc.
Implementation
In this section, we will create a sample android application that will use toggle buttons. Follow the steps given below to make this sample application.
Creating an Android Studio Project
You need to first create an Android Studio project before actually creating your Android apps. To create a new project, open up Android Studio and press the New Project button, select Empty Activity as the activity type and implementation language as Kotlin. Select a minimum SDK version as per your requirements.
Don't have Android Studio and environment already set up in your machine? No worries, we got you all covered. Refer to the blog Android Studio and Environment Setup on the Coding Ninjas Website to set up things for a smoother development process.
The main activity XML file
The activity_main.xml file is the most important layout of your application which is referenced when we are building the interface of our application. The code for the ToggleButton widget is written in this file.
Code:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_height="match_parent"
xmlns:android="http://schemas.android.com/apk/res/android"
tools:context=".MainActivity"
android:background="@color/dirty_white"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent">
<TextView
android:id="@+id/textView"
android:layout_width="387dp"
android:layout_height="117dp"
android:layout_above="@+id/toggleButton"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:text="@string/welcome_text"
android:textAlignment="center"
android:textColor="@color/orange"
android:textSize="25dp"
android:textStyle="bold|italic"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.086" />
<ToggleButton
android:id="@+id/toggleButton"
android:layout_width="136dp"
android:layout_height="67dp"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:background="@color/navy_blue"
android:onClick="ToggleFunction"
android:textColor="@color/white"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.498"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.444" />
<TextView
android:id="@+id/textView2"
android:layout_width="271dp"
android:layout_height="51dp"
android:layout_above="@+id/toggleButton"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:textAlignment="center"
android:textColor="@color/black"
android:textSize="18dp"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.7" />
</androidx.constraintlayout.widget.ConstraintLayout>In the above code, note the following points. We have defined two TextView widgets and one ToggleButton widget in this file. The Toggle Button is sandwiched between the two Text Views. We have assigned the ID for the Toggle Button widget as toggleButton, and we have set the onClicked attribute to ToggleFunction. This function is defined in the MainActivity.kt file. Basically, this function describes the action that needs to be performed when the toggle button is clicked.
The main activity Kotlin file
This is the main file that gets your application running. This file contains the onCreate method, one of the first methods that get called after running our application. The code for MainActivity.kt file is given as below.
Code:
package com.example.togglebutton
import androidx.appcompat.app.AppCompatActivity
import android.widget.ToggleButton
import android.widget.TextView
import android.os.Bundle
import android.view.View
import com.example.togglebutton.R
class MainActivity : AppCompatActivity() {
var togglebutton: ToggleButton? = null
var textview: TextView? = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
togglebutton = findViewById<View>(R.id.toggleButton) as ToggleButton
textview = findViewById<View>(R.id.textView2) as TextView
}
fun ToggleFunction(view: View?) {
if (!togglebutton!!.isChecked) {
textview!!.text = "Toggle Button is OFF"
} else {
textview!!.text = "Toggle Button is ON"
}
}
}The ToggleFunction defined in this file references the second TextView defined in the activity_main.xml file. Depending upon the state of the Toggle Button, it sets the text of the TextView with ID textView2.
The Android Manifest XML file
This file is used for registering our activities. We don’t need to change anything in this file and just use the boilerplate code provided by Android Studio for this. The code for the AndroidManifest.xml file is given below.
Code:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.togglebutton">
<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/Theme.ToggleButton">
<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>The Resources directory
The resources folder named res in our Android Studio project is an important folder that contains all the resources for our application. It contains all non-coding assets of our application. For example, consider the strings.xml file present under the directory res/values. This file contains the name of the application, which is rendered when we run the application. The code of this file is written below. In this blog, we have named the application as Toggle Button.
Code:
<resources>
<string name="app_name">Toggle Button</string>
<string name="welcome_text">Welcome to Toggle Button Tutorial\nBy Coding Ninjas</string>
</resources>The code for the colors.xml file is given as follows.
Code:
<?xml version="1.0" encoding="utf-8"?>
<resources>
<color name="purple_200">#FFBB86FC</color>
<color name="purple_500">#FF6200EE</color>
<color name="purple_700">#FF3700B3</color>
<color name="teal_200">#FF03DAC5</color>
<color name="teal_700">#FF018786</color>
<color name="black">#FF000000</color>
<color name="white">#FFFFFFFF</color>
<color name="orange">#FF8C00</color>
<color name="dirty_white">#F0EAD6</color>
<color name="navy_blue">#02075D</color>
</resources>
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