[Java] how to embed JavaScript

Embed JavaScript (J2v8)

if( ((String)langCombo.getSelectedItem()).equalsIgnoreCase("javascript") ) {
    SwingUtilities.invokeLater(() -> {
        try {
            boolean useNodeJS = false;
            V8 v8;
            if( useNodeJS ) {
                NodeJS nodeJS = NodeJS.createNodeJS();
                v8 = nodeJS.getRuntime();
            } else {
                v8 = V8.createV8Runtime();
            }
            v8.registerJavaMethod(j8print, "write"); 
            v8.registerJavaMethod(j8println, "writeln"); 
            outputPrintLn("<START Javascript>");
            v8.executeObjectScript(textTab.getSelectedTextView().getText());
            outputPrintLn("<END Javascript>");
        } catch (Exception e) {
            e.printStackTrace();
            outputPrintLn("error\n" + e.getMessage());
        }  
    });
}  

JavaVoidCallback j8print = new JavaVoidCallback() {
  public void invoke(final V8Object receiver, final V8Array parameters) {
    if (parameters.length() > 0) {
      Object arg1 = parameters.get(0);
      outputPrint((String)arg1);
      if (arg1 instanceof Releasable) {
        ((Releasable) arg1).release();
      }
    }
  }
 };

JavaVoidCallback j8println = new JavaVoidCallback() {
    public void invoke(final V8Object receiver, final V8Array parameters) {
        if (parameters.length() > 0) {
            Object arg1 = parameters.get(0);
            outputPrintLn((String)arg1);
            if (arg1 instanceof Releasable) {
                ((Releasable) arg1).release();
            }
        }
    }
};