小编hai*_*504的帖子

鉴于我们有一份银行清单,每家银行都有多个办事处,

public class Bank {
   private String name;
   private List<String> branches;
   public String getName(){
       return name;
   }
   public List<String> getBranches(){
       return branches;
   }
}

例如:

Bank "Mizuho": branches=["London", "New York"]
Bank "Goldman": branches = ["London", "Toronto"]

根据银行名单,我会得到每个城市的银行代表地图.在上面的例子中,我需要一个结果

Map["London"] == ["Mizuho", "Goldman"]
Map["New York"] == ["Mizuho"]
Map["Toronto"] == ["Goldman"]

如何使用Java 8 API实现该结果？使用pre-Java8很容易,但很冗长.谢谢.