Android WebView in Kotlin

WebView is a view that is used to display web pages inside the app. It is used to turn the app into a web application. In this article let’s display the https://www.geeksforgeeks.org/ inside the Android Application using Kotlin.

Note: To implement Android WebView in Java please refer How to use WebView in Android using Java.

Class Hierarchy

kotlin.Any
     android.view.View
          android.view.ViewGroup
               android.widget.AbsoluteLayout
                    android.webkit.WebView

Approach:

Step 1: Create a new project

To create a new project in android studio please refer, how to Create/Start a New Project in Android Studio.

Remember to add these to your gradle(app) files

plugins 
{
   id 'com.android.application'
   id 'kotlin-android'
   id 'kotlin-android-extensions'
}

Step 2: Modify activity_main.xml

This is used to set the front end of the Application, we place the WebView in the front end. 

XML

<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <!-- Place Web-view on the Screen -->
    <WebView
        android:id="@+id/webView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</androidx.constraintlayout.widget.ConstraintLayout>

Step 3: Modify MainActivity.kt

This is the back end of the Application, here we assign values to the views and actions to the views.

Kotlin

package com.example.webview_kotlin

import android.os.Bundle
import android.webkit.WebViewClient
import androidx.appcompat.app.AppCompatActivity
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {
    private lateinit var webView: WebView

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

        webView = findViewById(R.id.webView)
        // WebViewClient allows you to handle
        // onPageFinished and override Url loading.
        webView.webViewClient = WebViewClient()

        // this will load the url of the website
        webView.loadUrl("https://www.geeksforgeeks.org/")

        // this will enable the javascript settings, it can also allow xss vulnerabilities
        webView.settings.javaScriptEnabled = true

        // if you want to enable zoom feature
        webView.settings.setSupportZoom(true)
    }

    // if you press Back button this code will work
    override fun onBackPressed() {
        // if your webview can go back it will go back
        if (webView.canGoBack())
            webView.goBack()
        // if your webview cannot go back
        // it will exit the application
        else
            super.onBackPressed()
    }
}

Step 4: Modify AndroidManifest.xml

In AndroidManifest.xml, one needs to include the below permission, in order to access the internet.

XML

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="com.example.webview_kotlin">

    <!-- Give permission for app to access the Internet -->
    <uses-permission android:name="android.permission.INTERNET"/>

   <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>

Output: Run on Emulator

When we run the application either on the Emulator or on the Android Smartphone we can see this as our output. Remember to turn on the internet on your device.