在Java中创建复杂的HashMap [英] Creating complex HashMap in Java

问题描述

创建HashMap的最简单的方式是这样的：

What is the easiest way to create a HashMap like this :

( student1 => Map( name => Tim,         
                   Scores => Map( math => 10,
                                  physics => 20,
                                  Computers => 30),
                   place => Miami,
                   ranking => Array(2,8,1,13),
                ), 
student2 => Map ( 
                  ...............
                  ...............
                ),
............................
............................
);

我尝试过：

HashMap record = new HashMap();
record.put("student1", new HashMap());
record.get("student1").put("name","Tim");
record.get("student1").put("Scores", new HashMap());

但是我收到错误。我这样做是因为， record.get（student1）是一个HashMap对象，所以我假设一个 put

But I get error. I do it that way because, record.get("student1") is a HashMap object, so I assume a put on that should work, and so on.

如果它不起作用，最好的方法是什么？

If it doesnt work, what is the best way to do it ?

推荐答案

你得到这个异常，因为 get（）返回一个类型 Object 。您需要将其转换为地图。

You get that exception because get() returns a type Object. you need to cast that to a Map.

((Map)record.get("student1")).put("name","Tim");

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