Java GSON抛出“预期是BEGIN_OBJECT，但是是BEGIN_ARRAY”？

Question

我正在尝试解析这样的JSON字符串

[
   {
      "updated_at":"2012-03-02 21:06:01",
      "fetched_at":"2012-03-02 21:28:37.728840",
      "description":null,
      "language":null,
      "title":"JOHN",
      "url":"http://rus.JOHN.JOHN/rss.php",
      "icon_url":null,
      "logo_url":null,
      "id":"4f4791da203d0c2d76000035",
      "modified":"2012-03-02 23:28:58.840076"
   },
   {
      "updated_at":"2012-03-02 14:07:44",
      "fetched_at":"2012-03-02 21:28:37.033108",
      "description":null,
      "language":null,
      "title":"PETER",
      "url":"http://PETER.PETER.lv/rss.php",
      "icon_url":null,
      "logo_url":null,
      "id":"4f476f61203d0c2d89000253",
      "modified":"2012-03-02 23:28:57.928001"
   }
]

进入对象列表。

List<ChannelSearchEnum> lcs = (List<ChannelSearchEnum>) new Gson().fromJson( jstring , ChannelSearchEnum.class);

这是我正在使用的对象类。

import com.google.gson.annotations.SerializedName;

public class ChannelSearchEnum {



@SerializedName("updated_at")
private String updated_at;

@SerializedName("fetched_at")
private String fetched_at;

@SerializedName("description")
private String description;

@SerializedName("language")
private String language;

@SerializedName("title")
private String title;

@SerializedName("url")
private String url;

@SerializedName("icon_url")
private String icon_url;

@SerializedName("logo_url")
private String logo_url;

@SerializedName("id")
private String id;

@SerializedName("modified")
private String modified;

public final String get_Updated_at() {
    return this.updated_at;
}

public final String get_Fetched_at() {
    return this.fetched_at;
}

public final String get_Description() {
    return this.description;
}

public final String get_Language() {
    return this.language;
}

public final String get_Title() {
    return this.title;
}

public final String get_Url() {
    return this.url;
}

public final String get_Icon_url() {
    return this.icon_url;
}

public final String get_Logo_url() {
    return this.logo_url;
}

public final String get_Id() {
    return this.id;
}

public final String get_Modified() {
    return this.modified;
}

        }

但这让我着迷

com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 2

有什么想法我应该如何解决？

Answer 1

问题是你要告诉Gson你具有你类型的对象。你不知道 你有一系列类型的对象。你不能只是尝试像这样投射结果并期望它神奇地工作；）

《用户指南》Gson介绍了如何处理此问题：

https://github.com/google/gson/blob/master/UserGuide.md

这将起作用：

ChannelSearchEnum[] enums = gson.fromJson(yourJson, ChannelSearchEnum[].class);

但这更好：

Type collectionType = new TypeToken<Collection<ChannelSearchEnum>>(){}.getType();
Collection<ChannelSearchEnum> enums = gson.fromJson(yourJson, collectionType);