How to detect click on HTML button through javascript in Android WebView using Kotlin?

Kotlin Apps/Applications Mobile Development

This example demonstrates how to detect click on HTML buttons through javascript in Android WebView using Kotlin.This example demonstrates how to detect click on HTML buttons through javascript in Android WebView 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.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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">
   <TextView
      android:id="@+id/textView"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerHorizontal="true"
      android:layout_marginTop="70dp"
      android:background="#008080"
      android:padding="5dp"
      android:text="TutorialsPoint"
      android:textColor="#fff"
      android:textSize="24sp"
      android:textStyle="bold" />
   <Button
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:layout_centerInParent="true"
      android:onClick="loadPage"
      android:text="Load web Page" />
</RelativeLayout>

Step 3 − Create an asset folder and create a file.htm and add the following code −

<html>
<body>
First name: <input type="text" name="firstName" id="txtFirstName"><br>
Last name: <input type="text" name="lastName" id="txtLastName"><br>
<script>
   function getValues() {
      document.getElementById("btnOK").value =
      document.getElementById("txtFirstName").value+"
      "+document.getElementById("txtLastName").value;
   }
</script>
<button type="button" value="" id="btnOK" onclick=" getValues();ok.performClick(this.value); "> OK
</button>
</body>
</html>

Step 4 − Add the following code to src/MainActivity.kt

import android.annotation.SuppressLint
import android.os.Bundle
import android.view.View
import android.webkit.JavascriptInterface
import android.webkit.WebView
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
class MainActivity : AppCompatActivity() {
   override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.activity_main)
      title = "KotlinApp"
   }
   @SuppressLint("JavascriptInterface")
   fun loadPage(view: View) {
      val browser = WebView(this)
      browser.settings.javaScriptEnabled = true
      browser.loadUrl("file:///android_asset/page.html")
      setContentView(browser)
      val ws = browser.settings
      ws.javaScriptEnabled = true
      browser.addJavascriptInterface(object:Any() {
         @JavascriptInterface // For API 17+
         fun performClick(string:String) {
            Toast.makeText(this@MainActivity, string, Toast.LENGTH_SHORT).show()
         }
      }, "ok")
   }
}

Step 5 − Add the following code to androidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://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.

Azhar

Published on 07-Sep-2020 11:31:28

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