Adding alert() support to a WebView - Android

MainActivity.java

/* 
  Retrieved from https://web.archive.org/web/20160516165158/http://lexandera.com/2009/01/adding-alert-support-to-a-webview/
*/

final WebView browser = (WebView)findViewById(R.id.browser);  
/* JavaScript must be enabled if you want it to work, obviously */   
browser.getSettings().setJavaScriptEnabled(true);  
  
final Context myApp = this;  
  
/* WebChromeClient must be set BEFORE calling loadUrl! */  
browser.setWebChromeClient(new WebChromeClient() {  
    @Override  
    public boolean onJsAlert(WebView view, String url, String message, final android.webkit.JsResult result)   
    {  
        new AlertDialog.Builder(myApp)  
            .setTitle("javaScript dialog")  
            .setMessage(message)  
            .setPositiveButton(android.R.string.ok,  
                    new AlertDialog.OnClickListener()   
                    {  
                        public void onClick(DialogInterface dialog, int which)   
                        {  
                            result.confirm();  
                        }  
                    })  
            .setCancelable(false)  
            .create()  
            .show();  
          
        return true;  
    };  
});  
  
/* load a web page which uses the alert() function */  
browser.loadUrl("http://lexandera.com/files/jsexamples/alert.html"); 

Code for adding support for confirm() and prompt() is almost identical and can be found in Mosembro’s source code.

If you get the error that Context and AlertDialog can not be resolved, you need to

import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;

Erro: http://prntscr.com/nn0oee

package br.com.aaaaa;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.webkit.WebChromeClient;
import android.webkit.WebView;

import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        final WebView browser = (WebView)findViewById(R.id.browser);
        /* JavaScript must be enabled if you want it to work, obviously */
        browser.getSettings().setJavaScriptEnabled(true);

        final Context myApp = this;

        /* WebChromeClient must be set BEFORE calling loadUrl! */
        browser.setWebChromeClient(new WebChromeClient() {
            @Override
            public boolean onJsAlert(WebView view, String url, String message, final android.webkit.JsResult result)
            {
                new AlertDialog.Builder(myApp)
                        .setTitle("javaScript dialog")
                        .setMessage(message)
                        .setPositiveButton(android.R.string.ok,
                                new AlertDialog.OnClickListener()
                                {
                                    public void onClick(DialogInterface dialog, int which)
                                    {
                                        result.confirm();
                                    }
                                })
                        .setCancelable(false)
                        .create()
                        .show();

                return true;
            };
        });

        /* load a web page which uses the alert() function */
        browser.loadUrl("http://lexandera.com/files/jsexamples/alert.html");


    }
}