为何properties.store方法存储properties对象中的内容，每个属性和关键字必须用string类型，要么就发生异常？

属性文件中每个属性是用字符串表示的
public void store(OutputStream out,String comments) throws IOException
方法定义时已经声明是String类型了，你再给他传递非String 类型的当然要发生异常

查阅JDK，发现有个原因：
Because Properties inherits from Hashtable, the put and putAll methods can be applied to a Properties object.
Their use is strongly discouraged as they allow the caller to insert entries whose keys or values are not Strings.
[ 本帖最后由 孙斌 于 2011-07-23  15:05 编辑 ]