如何将对象向上转换为 java.util.Map？

How to upcast an Object to a java.util.Map?

提问by user441174

I have an object in my code of the type Object: Object o

我的代码中有一个 Object 类型的对象： Object o

The class of the instance is Object: o.getClass()gives Object.

实例的类是Object：o.getClass()给出Object。

Now, it should be a Map! How can I upcast this to a Map?

现在，它应该是一张地图！我如何将其上传到地图？

I tried: Map<String, Object> map = (HashMap<String,Object>)o

我试过： Map<String, Object> map = (HashMap<String,Object>)o

But this returns: java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to java.util.HashMap

但这会返回： java.lang.ClassCastException: [Ljava.lang.Object; 不能转换为 java.util.HashMap

The instance 'o' comes from a XMLRPC request. This request does not qualify variables correctly supposedly

实例“o”来自 XMLRPC 请求。这个请求没有正确地限定变量

Please have a look at this!?

请看看这个！？

EDIT:

编辑：

Now I have the following issue: o.getClass().getName()gives java.util.ArrayList,

现在我有以下问题： o.getClass().getName()给出java.util.ArrayList，

o.get(0)gives [Ljava.lang.Object;@739e8329,

o.get(0)给[Ljava.lang.Object;@739e8329,

and o.get(0).getClass().getName()gives java.lang.String.

并o.get(0).getClass().getName()给出java.lang.String.

I cannot findout what to do..

我不知道该怎么做..

EDIT2:

编辑2：

Finally I found out what happened. The software that created this object flattened a datastructure into a String (valueOf()). So, when I printed the variable it returned a [Ljava.util.Object, which was in fact a String containing this information.

终于我知道发生了什么。创建此对象的软件将数据结构扁平化为字符串 (valueOf())。因此，当我打印该变量时，它返回一个 [Ljava.util.Object，它实际上是一个包含此信息的字符串。

Thanks guys!

谢谢你们！

采纳答案by Grzegorz Oledzki

[Ljava.lang.Objectindicates the type of the object o is an array of Objects - that is Object[]. You cannot cast it to Map.

[Ljava.lang.Object表示对象 o 的类型是一个对象数组 - 即Object[]. 您不能将其转换为Map.

You might find it useful if took a look at: java: what is this: [Ljava.lang.Object;?

如果查看以下内容，您可能会发现它很有用：java: what is this: [Ljava.lang.Object;?

You stated that .getClass()indicated Object, but was it Objector [LObject? Compare to:

你说这.getClass()表明Object，但它Object还是[LObject？相比于：

    Object[] array= new Object[]{};
    Object simple = new Object();

    System.out.println(array.getClass());
    System.out.println(simple.getClass());      

which prints:

打印：

class [Ljava.lang.Object;
class java.lang.Object

回答by Andreas Dolk

The error clearly indicates, that odoes not implement the Mapinterface. So it is impossible to cast this object to Map.

错误清楚地表明，o没有实现Map接口。所以不可能将此对象强制转换为Map.

The result is an array of Objects. Maybe, the array actually holds maps. Try if this works:

结果是一个对象数组。也许，该数组实际上包含地图。试试这是否有效：

 Object[] objects = (Object[]) o;
 if (objects != null && objects.length > 0) {
    Object object = objects[0];
    if (object instanceof Map) {
      Map map = (Map) object;
      System.out.println("Heureka!");
    }
 }

回答by amorfis

You cannot cast oto Map, because it does not implement Mapinterface. Exception shows that ois array of Objects.

您不能强制转换o为Map，因为它没有实现Map接口。异常表明它o是Objects 的数组。

回答by Darshil Shah

ObjectMapper oMapper = new ObjectMapper();
    Map<String, String> map = oMapper.convertValue(YOUROBJECT, Map.class);
    List<InputValues> inputValuesList = new ArrayList<InputValues>();
   for(String key : map.keySet()){
        inputValuesList.add(new InputValues(key,map.get(key).toString()) );
    }


    <dependency>
        <groupId>com.fasterxml.Hymanson.core</groupId>
        <artifactId>Hymanson-databind</artifactId>
        <version>2.9.9</version>
    </dependency>

InputValues class has 2 Strings.Also Hymanson Dependency has to be added.

InputValues 类有 2 个字符串。还必须添加 Hymanson 依赖项。