Execute Javascript in webview

WebViewActivity.java

public class MainActivity extends AppCompatActivity {

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

        final WebView webview = (WebView) findViewById(R.id.webview);
        webview.getSettings().setJavaScriptEnabled(true);
        webview.loadUrl("http://xxx.xxx.xxx.xxx:yyyy/form");
        webview.setWebViewClient(new WebViewClient(){
            @Override
            public void onPageFinished(WebView view, String url) {
                super.onPageFinished(view, url);

                String script = "document.getElementsByName(\"fullname\")[0].setAttribute(\"value\", \"pamir cevikogullari\" ) ";
                webview.evaluateJavascript(script, new ValueCallback<String>() {
                    @Override
                    public void onReceiveValue(String s) {
                        Log.d("LogName", s);
                    }
                });
            }
        });
    }
}