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How can I prevent gson from converting integers to doubles

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再見小時候
再見小時候 2020-12-05 07:37

I\'ve got integers in my json, and I do not want gson to convert them to doubles. The following does not work:

@Test
public void keepsIntsAsIs(){
    String
6条回答
  • 执念已碎
    执念已碎 (楼主)
    2020-12-05 08:22

    This worked for me, I have a "specs" field which is a Map:

    public class MyClass {

  public Map specs;

}

    Before the fix I was getting this output for a list of these objects:

    {  
   "hits":{  
      "content":[  
         {  
            "specs":{  
               "fiscalHorsePower":4.0,
               "nbOfDoors":5.0,
               "consumption":4.3
            }
         }
      ]
   }
}

    fiscalHorsePower and nbOfDoors are integer.

    Here is the fix I used, first create a new Adapter and a Factory:

    public class CustomizedObjectTypeAdapter extends TypeAdapter {

public static final TypeAdapterFactory FACTORY = new TypeAdapterFactory() {
    @SuppressWarnings("unchecked")
    @Override public  TypeAdapter create(Gson gson, TypeToken type) {
        if (Map.class.isAssignableFrom(type.getRawType())) {
            return (TypeAdapter) new CustomizedObjectTypeAdapter();
        }
        return null;
    }
};

private final TypeAdapter delegate = new Gson().getAdapter(Object.class);

@Override
public void write(JsonWriter out, Object value) throws IOException {
    delegate.write(out, value);
}

@Override
public Object read(JsonReader in) throws IOException {
    JsonToken token = in.peek();
    switch (token) {
        case BEGIN_ARRAY:
            List list = new ArrayList();
            in.beginArray();
            while (in.hasNext()) {
                list.add(read(in));
            }
            in.endArray();
            return list;

        case BEGIN_OBJECT:
            Map map = new LinkedTreeMap();
            in.beginObject();
            while (in.hasNext()) {
                map.put(in.nextName(), read(in));
            }
            in.endObject();
            return map;

        case STRING:
            return in.nextString();

        case NUMBER:
            //return in.nextDouble();
            String n = in.nextString();
            if (n.indexOf('.') != -1) {
                return Double.parseDouble(n);
            }
            return Long.parseLong(n);

        case BOOLEAN:
            return in.nextBoolean();

        case NULL:
            in.nextNull();
            return null;

        default:
            throw new IllegalStateException();
    }
}
}



    And then register the factory:
    


    Gson gson = new GsonBuilder().registerTypeAdapterFactory(CustomizedObjectTypeAdapter.FACTORY);

    


    and here is the result with the fix:
    


    {  
   "hits":{  
      "content":[  
         {  
            "specs":{  
               "fiscalHorsePower":4,
               "nbOfDoors":5,
               "consumption":4.3
            }
         }
      ]
   }
}

    
    
    
             
    
                                                        
    
            
            
    
              
                
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