您应该打印 rs.getInt（1）。当您从某个表中选择某些数据的计数时，结果将作为结果集中的整数列返回。

You should print rs.getInt (1). When you select a count of some data from some table, the result is returned as an integer column in the result set.

请尝试：

JOptionPane.showMessageDialog（null，现有停车位数为+ rs.getInt（1））;