Android: run Javascript in WebView

Good afternoon, you need to automatically click on the button at the end of loading the page in WebView. I do this, but the button is clicked from the WebView, but not programmatically. What can be done in this situation? Thanks.

public class RostelecomLoginActivity extends Activity {

WebView webView;
String url;

@SupressLint("SetJavaScriptEnabled")
@Override
protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    this.getWindow().requestFeature(Window.FEATURE_NO_TITLE);
    setContentView(R.layout.activity_rostelecom_login);

    Intent webIntent = getIntent();
    final String url = webIntent.getStringExtra("url");

    webView = (WebView) findViewById(R.id.webView1);

    WebSettings webSettings = webView.getSettings();
    webSettings.setJavaScriptEnabled(true);
    webSettings.setSavePassword(true);
    webSettings.setSaveFormData(true);
    webSettings.setJavaScriptCanOpenWindowsAutomatically(true);

    webView.setWebViewClient(new WebViewClient() {

        public void onPageLoad(WebView view, String url) {
        }

        public void onPageStarted() {
        }

        public void onPageFinished(WebView view, String url) {
            webView.loadUrl("javascript:document.getElementById('mA').click()");
        }

        public void onReceivedSslError(WebView view, SslErrorHandler handler, SslError error) {
            handler.proceed();
        }

        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            return false;
        }
    });

    webView.loadUrl(url);
}
}