code: public static boolean iconExists(@NonNull Context context, @NonNull String icon) {
          try {
              ITypeface font = findFont(context, icon.substring(0, 3));
              icon = icon.replace("-", "_");
              font.getIcon(icon);
              return true;
          } catch (Exception ignore) {
              return false;
          }
      }
docs: Test if the icon exists in the currently loaded fonts
  
  @param context A context to access application resources
  @param icon    The icon to verify
  @return true if the icon is available