document.getElementsByName NOT working in some websites in webview in android

Issue

i build new android app and use java script syntax document.getElementsByName('') to insert value in input field in web page . but not working in some web page that i load it in web view in android studio

here the code

 webCollection =(WebView)findViewById(R.id.webCollection);

 webCollection.getSettings().setJavaScriptEnabled(true);
 webCollection.getSettings().setDomStorageEnabled(true);



  webCollection.loadUrl("mywepSite");

               webCollection.setWebViewClient(new WebViewClient(){
                   @Override
                   public void onPageFinished(WebView view, String url) {
                       super.onPageFinished(view, url);


  view.loadUrl("javascript:(function(){document.getElementsByName('j_username')[0].value='myUser';document.getElementsByName('j_password')[0].value='MyPassword';document.getElementsByTagName('form')[0]();})()");

                   }
               });

           }
       });

here the input field

<input name="j_username" tabindex="1" class="form-control input-lg margin-bottom" id="j_username" spellcheck="false" type="text" size="15" autocapitalize="off" autocorrect="off" autocomplete="off" data-required="Please enter required fields.">

<input name="j_password" tabindex="1" class="form-control input-lg margin-bottom" id="j_password" spellcheck="false" type="text" size="15" autocapitalize="off" autocorrect="off" autocomplete="off" data-required="Please enter required fields.">

Solution

this is a working class that can load a webview successfully

import android.app.Activity;
import android.os.Bundle;
import android.webkit.WebResourceError;
import android.webkit.WebResourceRequest;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Toast;
import android.annotation.TargetApi;

public class Main extends Activity {

    private WebView mWebview ;

    @Override
    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        mWebview  = new WebView(this);

        mWebview.getSettings().setJavaScriptEnabled(true); // enable javascript

        final Activity activity = this;

        mWebview.setWebViewClient(new WebViewClient() {
            @SuppressWarnings("deprecation")
            @Override
            public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {
                Toast.makeText(activity, description, Toast.LENGTH_SHORT).show();
            }
            @TargetApi(android.os.Build.VERSION_CODES.M)
            @Override
            public void onReceivedError(WebView view, WebResourceRequest req, WebResourceError rerr) {
                // Redirect to deprecated method, so you can use it in all SDK versions
                onReceivedError(view, rerr.getErrorCode(), rerr.getDescription().toString(), req.getUrl().toString());
            }
        });

        mWebview .loadUrl("http://www.google.com");
        setContentView(mWebview );

    }

}

Dont forget to add Permission

<uses-permission `android:name="android.permission.INTERNET" />

Answered By - TanvirChowdhury