webView | Native App | Open Website in Anderiod App |

There are many ways to write your webview code. Here is an example of how I do it.

This is a webview class complete with page load progressbar and the ability to download from any download links. You can also pass any url to it or as many as you like. If you only need one static url, then change the "static String url" with your static url.

Read the comments within the code as they explain what everything does.

Code (Java):

1. package com.webviewexample;
2.  
3. import android.Manifest;
4. import android.annotation.SuppressLint;
5. import android.app.DownloadManager;
6. import android.content.pm.PackageManager;
7. import android.graphics.Bitmap;
8. import android.net.Uri;
9. import android.os.Build;
10. import android.os.Bundle;
11. import android.os.Environment;
12. import android.view.View;
13. import android.webkit.CookieManager;
14. import android.webkit.DownloadListener;
15. import android.webkit.URLUtil;
16. import android.webkit.WebView;
17. import android.webkit.WebViewClient;
18. import android.widget.ProgressBar;
19. import android.widget.Toast;
20.  
21. import androidx.annotation.NonNull;
22. import androidx.appcompat.app.AppCompatActivity;
23. import androidx.core.app.ActivityCompat;
24.  
25. public class MyWebView extends AppCompatActivity {
26.     // Declare our web view.
27.     private WebView webview;
28.  
29.     // We can pass URLs from any other class to this string.
30.     static String url;
31.  
32.     // Optional progress bar for page loading progress.
33.     private ProgressBar progress;
34.  
35.     // A request code for our storage write request.
36.     private static final int WRITE_STORAGE = 1;
37.  
38.     @SuppressLint("SetJavaScriptEnabled")
39.     @Override
40.     protected void onCreate(Bundle savedInstanceState) {
41.         super.onCreate(savedInstanceState);
42.         setContentView(R.layout.activity_webview);
43.  
44.         // Optional progress bar for page loading progress.
45.         progress = findViewById(R.id.progressBar);
46.  
47.         // Attach our web view to our layout.
48.         webview = findViewById(R.id.webView);
49.         // Needed to interact with elements on most web pages.
50.         webview.getSettings().setJavaScriptEnabled(true);
51.         // This enables pinch to zoom.
52.         webview.getSettings().setBuiltInZoomControls(true);
53.         // Do not display the zoom controls on the screen.
54.         webview.getSettings().setDisplayZoomControls(false);
55.         // Loads a page to fit in the screen (zoomed out).
56.         webview.getSettings().setLoadWithOverviewMode(true);
57.         // Do not constrain the viewport to the web view dimensions.
58.         webview.getSettings().setUseWideViewPort(true);
59.         // Attach our web view to our WebViewClient.
60.         webview.setWebViewClient(new MyWebViewClient());
61.         // We call our url string variable to load.
62.         webview.loadUrl(url);
63.  
64.         // Adds a DownloadListener to our web view. This allows us to click on
65.         // download links and have items download to our downloads directory.
66.         webview.setDownloadListener(new DownloadListener() {
67.             public void onDownloadStart(String url, String userAgent, String contentDisposition, String mimetype, long contentLength) {
68.                 String fileName = URLUtil.guessFileName(url, contentDisposition, mimetype);
69.                 String cookie = CookieManager.getInstance().getCookie(url);
70.                 DownloadManager dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
71.                 DownloadManager.Request request = new DownloadManager.Request(Uri.parse(url));
72.                 request.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_WIFI | DownloadManager.Request.NETWORK_MOBILE);
73.                 request.setAllowedOverRoaming(false);
74.                 request.allowScanningByMediaScanner();
75.                 request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, fileName);
76.                 request.addRequestHeader("Cookie", cookie);
77.                 request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
78.                 // Check for storage write permission before attempting to download.
79.                 if (getPermission()) {
80.                     dm.enqueue(request);
81.                 }
82.             }
83.         });
84.  
85.     }
86.  
87.     // Check if storage write permission has been granted. If not, request it.
88.     private boolean getPermission() {
89.         if (Build.VERSION.SDK_INT >= 23) {
90.             if (ActivityCompat.checkSelfPermission(this,
91.                     Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
92.                 // True if permission granted exists.
93.                 return true;
94.             } else {
95.                 // We ask for storage write permission if it doesn't exist.
96.                 ActivityCompat.requestPermissions(this,
97.                         new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, WRITE_STORAGE);
98.                 return false;
99.             }
100.         } else {
101.             // True for SDK < 23
102.             return true;
103.         }
104.     }
105.  
106.     // Check if user granted or denied storage write permission when requested and
107.     // run code for either situation. This method is optional, but useful.
108.     @Override
109.     public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
110.         switch (requestCode) {
111.             case WRITE_STORAGE: {
112.                 if (grantResults.length > 0 &amp;&amp; grantResults[0] == PackageManager.PERMISSION_GRANTED) {
113.                     Toast.makeText(getApplicationContext(), "Permission Granted!", Toast.LENGTH_LONG).show();
114.                 } else {
115.                     Toast.makeText(getApplicationContext(), "Permission Denied!", Toast.LENGTH_LONG).show();
116.                 }
117.             }
118.         }
119.     }
120.  
121.     // Attach our web view to our WebViewClient.
122.     private class MyWebViewClient extends WebViewClient {
123.         // This method makes sure that any links we click will open within
124.         // our app instead of launching in the default web browser.
125.         @Override
126.         public boolean shouldOverrideUrlLoading(WebView view, String url) {
127.             return super.shouldOverrideUrlLoading(view, url);
128.         }
129.  
130.         // Since this method is called every time a new page starts to load, it's
131.         // perfect to run our Progress Bar.
132.         @Override
133.         public void onPageStarted(WebView view, String url, Bitmap favicon) {
134.             progress.setVisibility(View.VISIBLE);
135.             super.onPageStarted(view, url, favicon);
136.         }
137.  
138.         // Called whenever a page has finished loading. Here we can end our
139.         // page loading progress bar and take it out of view.
140.         @Override
141.         public void onPageFinished(WebView view, String url) {
142.             progress.setVisibility(View.GONE);
143.             super.onPageFinished(view, url);
144.         }
145.  
146.     }
147.  
148.     // If we have clicked through multiple pages, this allows the back button
149.     // to take us back through each page.
150.     @Override
151.     public void onBackPressed() {
152.         if (webview.canGoBack()) {
153.             webview.goBack();
154.         } else {
155.             super.onBackPressed();
156.         }
157.     }
158. }

You can then pass a url to this class from any other class like this...

Code (Java):

1. public void googleButton(View view) {
2.     MyWebView.url = "https://www.google.com/";
3.     Intent intent = new Intent(this, MyWebView.class);
4.     startActivity(intent);
5. }

I wrote a full tutorial complete with source code on github and a fully working app in the following link...
https://intechgeek.com/android-webview/

Try the sample app I provided to see if this code serves your purpose. Just check the app/release/ folder in the github source code.

 

First, that error would tend to indicate that you haven't imported WebView. @GameTheory's example shows that (line 16)

Also, your WebView doesn't have an ID, and you're trying to use an id to get it

Code (Text):

1. <WebView
2. android:layout_width="match_parent"
3. android:layout_height="match_parent"
4. tools:layout_editor_absoluteX="8dp"
5. tools:layout_editor_absoluteY="8dp" />

If you want to use ID, you'll need to add one, like

Code (Text):

1. <WebView
2. android:id="@+id/webview"
3. android:layout_width="match_parent"
4. android:layout_height="match_parent"
5. tools:layout_editor_absoluteX="8dp"
6. tools:layout_editor_absoluteY="8dp" />

and be sure to use the id exactly as defined.

Follow that link @GameTheory shared, it looks like it will give you a good start.