通过嵌套的hashmap迭代 [英] Iterate through nested hashmap

问题描述

我将如何去遍历嵌套的HashMap？

HashMap 是这样设置的：

  HashMap< String，HashMap< String，Student>> 
  

其中学生是一个包含变量的对象名称。例如，如果我的HashMap看起来像这样（下面不是我的代码，它只是模拟hashmap的内容）

  hm => HashMap<'S'，Hashmap<'Sam'，SamStudent>> 
 HashMap<'S'，Hashmap<'Seb'，SebStudent>> 
 HashMap<'T'，Hashmap<'Thomas'，ThomasStudent>> 
  

如何遍历所有单字母键，然后遍历每个全名键，然后拉出（Map.Entry< String，HashMap<>）的名字？

解决方案

  String，Student>> letterEntry：students.entrySet（））{
 String letter = letterEntry.getKey（）; 
 // ... 
 for（Map.Entry< String，Student> nameEntry：letterEntry.getValue（）。entrySet（））{
 String name = nameEntry.getKey（）; 
 Student student = nameEntry.getValue（）; 
 // ... 
} 
} 
  

How would I go about iterating through a nested HashMap?

The HashMap is setup like this:

HashMap<String, HashMap<String, Student>>

Where Student is an object containing a variable name. If for instance my HashMap looked like this (the following is not my code, it's just to simulate what the contents of the hashmap could be)

 hm => HashMap<'S', Hashmap<'Sam', SamStudent>>
       HashMap<'S', Hashmap<'Seb', SebStudent>>
       HashMap<'T', Hashmap<'Thomas', ThomasStudent>>

How could I iterate through all of the single letter keys, then each full name key, then pull out the name of the student?

解决方案

for (Map.Entry<String, HashMap<String, Student>> letterEntry : students.entrySet()) {
    String letter = letterEntry.getKey();
    // ...
    for (Map.Entry<String, Student> nameEntry : letterEntry.getValue().entrySet()) {
        String name = nameEntry.getKey();
        Student student = nameEntry.getValue();
        // ...
    }
}

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