Gson用数组解析Json [英] Gson parse Json with array

问题描述

我在构建一个能解析出gson的类的时候遇到了一些麻烦，因为我希望这样做。

我创建了一个类。

  public class JsonObjectBreakDown {
 public String type; 
 public List< String> coordinates = new ArrayList< String>（）; 
 
  

并称为

  JsonObjectBreakDown p = gson.fromJson（withDup，JsonObjectBreakDown.class）; 
  

以下是我的json

  {
type：Polygon，
coordinates：[
 [
 [
 -66.9，
 18.05 
]，
 [
 -66.9，
 18.05 
]，
 [
 -66.9，
 18.06 
]，
 [
 -66.9，
 18.05 
] 
] 
] 
} 
  

我已经成功地使用过gson，但从来没有像这样的数组。我应该不使用List / ArrayList吗？

我收到错误讯息;

 线程main中的异常com.google.gson.JsonSyntaxException：com.google.gson.stream.MalformedJsonException：未终止的对象在第1行第31列
  

OpenCSV代码

  CSVReader reader = new CSVReader（new FileReader（c：\\Json.csv））; 
 String tmp = reader.readNext（）; 
 CustomObject tmpObj = CustomObject（tmp [0]，tmp [1]，......）; 
  

解决方案

这里的问题是您有您的JSON中的浮点数字数组的数组。你的类应该是

  public class JsonObjectBreakDown {
 public String type; 
 public List< List< float []>> coordinates = new ArrayList<>（）; 
} 
  

解析上述内容并尝试

  System.out.println（p.coordinates.size（））; 
 System.out.println（p.coordinates.get（0）.size（））; 
 System.out.println（Arrays.toString（p.coordinates.get（0）.get（0）））; b 
 
 
 
 $ b $ p code> 1 
 2 
 [-66.9，18.05] 
  

I am having some trouble building a class which will parse out gson as I expect it to.

I created a class.

public class JsonObjectBreakDown {
    public String type; 
    public List<String> coordinates = new ArrayList<String>();
}

And called

JsonObjectBreakDown p = gson.fromJson(withDup, JsonObjectBreakDown.class);

Below is my json

  {
   "type":"Polygon",
   "coordinates":[
      [
         [
            -66.9,
            18.05
         ],
         [
            -66.9,
            18.05
         ],
         [
            -66.9,
            18.06
         ],
         [
            -66.9,
            18.05
         ]
      ]
   ]
}

I have used gson before successfully, but never with an array like this. Should I not be using the List/ArrayList?

I get the error message;

Exception in thread "main" com.google.gson.JsonSyntaxException: com.google.gson.stream.MalformedJsonException: Unterminated object at line 1 column 31

OpenCSV code

CSVReader reader = new CSVReader(new FileReader("c:\\Json.csv"));
String tmp = reader.readNext();
CustomObject tmpObj = CustomObject(tmp[0], tmp[1],......);

解决方案

The problem here is that you have an array of arrays of arrays of floating point numbers in your JSON. Your class should be

public class JsonObjectBreakDown {
    public String type; 
    public List<List<float[]>> coordinates = new ArrayList<>();
}

Parsing with the above and trying

System.out.println(p.coordinates.size());
System.out.println(p.coordinates.get(0).size());
System.out.println(Arrays.toString(p.coordinates.get(0).get(0)));

yields

1
2
[-66.9, 18.05]

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