json - 使用 gson 反序列化泛型

Question

我正在使用 GSON 1.4 并使用两个通用 arraylist<myObject> 序列化一个对象如下String data = Gson.toJson(object, object.class) .当我对其进行反序列化时，我会这样做 gson.fromJson(json, type);
可悲的是我得到

java.lang.IllegalArgumentException: Can not set java.util.ArrayList field ... to java.util.LinkedList

这是为什么 ？ GSON 文档指出，如果我使用 object.class 参数进行序列化，它支持泛型。任何的想法？谢谢。

我的课是:

public class IndicesAndWeightsParams {

    public List<IndexParams> indicesParams;
    public List<WeightParams> weightsParams;

    public IndicesAndWeightsParams() {
        indicesParams = new ArrayList<IndexParams>();
        weightsParams = new ArrayList<WeightParams>();
    }
    public IndicesAndWeightsParams(ArrayList<IndexParams> indicesParams, ArrayList<WeightParams> weightsParams) {
        this.indicesParams = indicesParams;
        this.weightsParams = weightsParams;
    }
}    
public class IndexParams {

    public IndexParams() {
    }
    public IndexParams(String key, float value, String name) {
      this.key = key;
      this.value = value;
      this.name = name;
    }
    public String key;
    public float value;
    public String name;
}

Answer 1

由于 Java 的类型删除，Gson 在集合方面有一些限制。您可以阅读更多相关信息 here .

从你的问题我看到你同时使用 ArrayList和 LinkedList .你确定你不是想只使用 List ，界面？

此代码有效:

List<String> listOfStrings = new ArrayList<String>();

listOfStrings.add("one");
listOfStrings.add("two");

Gson gson = new Gson();
String json = gson.toJson(listOfStrings);

System.out.println(json);

Type type = new TypeToken<Collection<String>>(){}.getType();

List<String> fromJson = gson.fromJson(json, type);

System.out.println(fromJson);

更新 :我把你的类(class)改成了这个，这样我就不用和其他类(class)混了:

class IndicesAndWeightsParams {

    public List<Integer> indicesParams;
    public List<String> weightsParams;

    public IndicesAndWeightsParams() {
        indicesParams = new ArrayList<Integer>();
        weightsParams = new ArrayList<String>();
    }
    public IndicesAndWeightsParams(ArrayList<Integer> indicesParams, ArrayList<String> weightsParams) {
        this.indicesParams = indicesParams;
        this.weightsParams = weightsParams;
    }
}

使用此代码，一切都对我有用:

ArrayList<Integer> indices = new ArrayList<Integer>();
ArrayList<String> weights = new ArrayList<String>();

indices.add(2);
indices.add(5);

weights.add("fifty");
weights.add("twenty");

IndicesAndWeightsParams iaw = new IndicesAndWeightsParams(indices, weights);

Gson gson = new Gson();
String string = gson.toJson(iaw);

System.out.println(string);

IndicesAndWeightsParams fromJson = gson.fromJson(string, IndicesAndWeightsParams.class);

System.out.println(fromJson.indicesParams);
System.out.println(fromJson.weightsParams);