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我正在使用 GSON 1.4 并使用以下两个泛型序列化一个arraylist<myObject>对象 String data = Gson.toJson(object, object.class)。当我对它进行反理想化时,我会gson.fromJson(json, type);

可悲的是我得到

java.lang.IllegalArgumentException:无法将 java.util.ArrayList 字段...设置为 java.util.LinkedList

这是为什么 ?GSON doc 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;
}
4

1 回答 1

23

由于 Java 的类型擦除,Gson 在集合方面有一些限制。你可以在这里阅读更多关于它的信息。

从您的问题中,我看到您同时使用ArrayListand LinkedList。你确定你不是要使用 just List, 界面吗?

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:我把你的课程改成了这个,所以我不必和其他课程混在一起:

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;
    }
}

使用这段代码,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);
于 2010-12-06T08:51:13.863 回答