if (o instanceof String s) {
    var foo = s.indexOf("bar");
  }

  return switch (o) {
     case Integer i -> String.format("int %d", i);
     case Long l    -> String.format("long %d", l);
     case Double d  -> String.format("double %f", d);
     case String s  -> String.format("String %s", s);
     default        -> o.toString();
  };