code: public void setTitle(CharSequence title){
          if(mConstruct != null && !mConstruct.getDesign().isMaterial()){
              // Modify the dialog's title element
              getDialog().setTitle(title);
          }else{
              if(mTitle != null){
                  mTitle.setText(title);
              }
          }
      }
docs: Modify the title of the dialog no matter what style it is
  
  @param title     the title to update with