我正在使用这个方法，它返回一个`Set<String>`，但实际上我得到的是一个像这样的Json字符串：

我的目标是获取键"id"的值。我还创建了一个Java Bean来映射数据：
```java
public class Data {
    private String id;
    private String title;
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
}

Set<String> availableData = getData(); // 这个方法返回一个json字符串
Iterator<String> itr = availableData.iterator();
while (itr.hasNext()) {
    Gson gson = new Gson();
    JsonParser parser = new JsonParser();
    JsonObject object = (JsonObject) parser.parse(itr.next());
    Data data = gson.fromJson(object, Data.class);
}

<details>
<summary>英文:</summary>
I&#39;m using this method that returns a `Set&lt;String&gt;` but in fact what I got is a Json string like this

My goal is to get the value of key "id". I've also made a java bean to map the data:
    public class Data {
        private String id;
        private String title;
    
        public String getId() {
            return id;
        }
    
        public void setId(String id) {
            this.id = id;
        }
    
        public String getTitle() {
            return title;
        }
    
        public void setTitle(String title) {
            this.title = title;
        }
    }
I tryied to parse using gson but all I can get is an error: Cannot cast 'java.util.LinkedHashMap$LinkedKeyIterator' to 'com.google.gson.stream.JsonReader'
So, obviously I'm doing something wrong:
    Set<String> availableData = getData(); //this method returns a json string
    Iterator<String> itr = availableData.iterator();
            while (itr.hasNext()) {
                Gson gson = new Gson();
                JsonParser parser = new JsonParser();
                JsonObject object = (JsonObject) parser.parse(itr.next());
                Data data = gson.fromJson(object, Data.class);
            }
update: The actual error is: Type mismatch Can't assign com.google.common.collect.Maps$TransformedEntriesMap to java.lang.String
</details>
# 答案1
**得分**: 1
在那一行中，你传递了一个迭代器：
```java
JsonObject object = (JsonObject) parser.parse((JsonReader) itr);

JsonObject object = (JsonObject) parser.parse(itr.next());

Data data = gson.fromJson(itr.next(), Data.class);

ObjectMapper objectMapper = new ObjectMapper();
String carJson =
    "{\"brand\": \"Mercedes\", \"doors\": 5}";
try {
    Car car = objectMapper.readValue(carJson, Car.class);
    System.out.println("car brand = " + car.getBrand());
    System.out.println("car doors = " + car.getDoors());
} catch (IOException e) {
    e.printStackTrace();
}

所以，根据这个相关问题：https://github.com/seleniumhq/selenium-google-code-issue-archive/issues/5154，最终我使用 Java 8 中的 JSONArray 和流进行了映射。
Set<String> availableData = getData();
JSONArray dataArray = new JSONArray(availableData);
List<Object> dataList = dataArray.toList();
Object o = dataList.stream()
        .filter(c -> ((Map) c).get("id").toString().contains("Id1"))
        .findFirst().orElse(null);
return ((Map)o).get("id").toString();

    public void parse() {
        String jsonString = "[
            {
                \"id\":\"Id1\"
            },
            {
                \"id\":\"Id2\",
                \"title\":\"anyTitle\"
            }
        ]";
        Gson gson = new Gson();
        
        // 使用 Gson 的 Type
        Type setType = new TypeToken<HashSet<Data>>(){}.getType();
        Set<Data> dataSet = gson.fromJson(jsonString, setType);
        
        // 输出 [Data{id='Id2', title='anyTitle'}, Data{id='Id1', title='null'}]
        System.out.println(dataSet);
        // 使用 Java 数组
        Data[] dataArray = gson.fromJson(jsonString, Data[].class);
        
        // 输出 [Data{id='Id1', title='null'}, Data{id='Id2', title='anyTitle'}]
        System.out.println(Arrays.toString(dataArray));
    }