1、 准备两个待合并的映射表，示例中通过新建获取，实际应用时应从数据库或其它数据源读取所需数据。 2、 调用putAll方法合并map时，需先判断对象是否为null。为避免map01为null导致无法合并map02，应新建一个map实例来确保操作顺利执行。

package dustin.examples; /** * Enum representing select western states in the United Sates. */ public enum States { ARIZONA("Arizona"), CALIFORNIA("California ...

A colleague of mine recently ran into an issue that I have not run into myself, but found to be interesting and, in my opinion, worth blogging about here. During some distributed Java development, my ...