How to use

isValid

method

in

com.vaadin.v7.ui.Field

@Override
public boolean isValid() {
  boolean res = true;
  getState().errorAmount = 0;
  for (FormSection formSection : getFormSections()) {
    for (Component fieldComponent : formSection) {
      boolean isFieldValid = ((Field) fieldComponent).isValid();
      if(!isFieldValid){
        ++getState().errorAmount;
      }
      res &= isFieldValid;
    }
  }
  return res;
}

&& !((Field<?>) f).isValid()) {