Is it possible to use JavaScript code in Android?

Question

in this code Android app opens a web page with WebView and extracts a text from HTML which is between tags "body" and "/body".

import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Button;
import android.widget.TextView;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Intent;

public class MainAc extends Activity {

    /** Called when the activity is first created. */
    @SuppressLint({ "JavascriptInterface", "SetJavaScriptEnabled" })
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        WebView webView = (WebView) findViewById(R.id.web);
        TextView text2 = (TextView) findViewById(R.id.text);

        Button infoButton = (Button) findViewById(R.id.b1);
        infoButton.setOnClickListener(new OnClickListener(){
            public void onClick(View view){
                // here is your button click logic, for example running another activity (page)
                startActivity(new Intent(MainAc.this, JavaInterface.class));
            }   
        });







        class Javasc { 
            private TextView t2;       

            public Javasc (TextView i)   
            {
                t2 = i;
            }

            @SuppressWarnings("unused") 

            public void processContent(String ii) 
            { 
                final String content = ii;
                t2.post(new Runnable() 
                {    
                    public void run() 
                    {          
                        t2.setText(content);        
                    }     
                });
            } 
        } 


        webView.getSettings().setJavaScriptEnabled(true); 
        webView.addJavascriptInterface(new Javasc(text2), "INTERFACE"); 
        webView.setWebViewClient(new WebViewClient() { 
            @Override 
            public void onPageFinished(WebView view, String url) 
            { 
                view.loadUrl("javascript:window.INTERFACE.processContent(document.getElementsByTagName('body')[0].innerText);"); 

            } 
        }); 

        webView.loadUrl("http://www.nytimes.com/2014/08/03/sports/basketball/pacers-paul-george-has-surgery-after-badly-injuring-leg.html?ref=sports");
    }

    }

Is it possible to use JavaScript functions for extracted text in android's TextView ?

for example this JavaScript function (or it could be any other JS function where need to work with text)

function myFunction() {
var text = document.body.innerText;
var titles =text.match(/^\n(.+?)\n\n/mg);
 for (var i = 0; i < titles.length; i++) {
   document.write(titles[i] + "<br />" + "<br />");
   }
   }

Thanks for answers :)

Answer 1

According to this article, the Dalvik VM supports Java's scripting features (javax.script). One of the premier languages supported by the javax.script stuff is, unsurprisingly, JavaScript.

So in theory, you can use the javax.script stuff to execute JavaScript code and get back results. I think (also based on that article), that you have to include the relevant jar(s) (javax.script isn't in the Android SDK). Fortunately, though, javax.script is largely a set of interfaces, which are implemented by jars for specific scripting languages.

Some resources about using javax.script to run script code:

• The Java Scripting API (Oracle)

• Java Scripting Programmer's Guide (Oracle)

Answer 2

You can use Rhino to achieve this. See specifically Context.jsToJava.

https://vec.io/posts/embed-javascript-in-android-java-code-with-rhino

Answer 3

You want to do a regex on a text and resorting to javascript for it, which is unnecessary when you have a better faster API in java with no overhead.

The equivalent to your example is:

http://developer.android.com/reference/java/util/regex/Pattern.html

Pattern p = Pattern.compile("/^\n(.+?)\n\n/mg");
 Matcher m = p.matcher(myTextView.getText());
 while (m.find()) {
     String titles = m.group(1);
     Log.V("TAG", titles);
 }

There are plenty of other text analysis solutions included in the core framework or external libraries that have been proved for both mobile and server. You just have to look it up and not resort to a worse API you're comfortable with.