问题描述
所以我试图用Gson解析Java中的JSON对象。我试图从网站上使用API。
这是代码：
JSON如下所示：
[
{
id：比特币，
名称：比特币，
符号：BTC，
rank：1，
price_usd：3591.95，
price_btc：1.0，
24h_volume_usd：3263990000.0，
market_cap_usd：59516499433.0，
available_supply：16569412.0，
total_supply：16569412.0，
percent_change_1h：1.02，
percent_change_24h：15.59，
percent_change_7d：-15.18，
last_updated：1505563475
}
]
我使用Jersey来使用API，我想将这个JSON转换为一个对象。
这是应该的对象通过解析JSON来构建：
public class CryptoCurrency {
String id;
字符串名称;
字符串符号;
字符串等级;
String price_usd;
String price_btc;
字符串market_cap_usd;
字符串available_supply;
字符串total_supply;
字符串percent_change_1h;
字符串percent_change_24h;
字符串percent_change_7d;
字符串last_updated;
$ / code $ / pre
这是我的代码：
public class CoinMarketCap {
public static void main（String [] args）{
Client client = ClientBuilder.newClient （）;
WebTarget target = client.target（https://api.coinmarketcap.com/v1/ticker/bitcoin/）;
String bitoinDeteils = target.request（MediaType.TEXT_XML）.get（String.class）;
Gson gson = new GsonBuilder（）。create（）;
CryptoCurrency bitcoin = gson.fromJson（bitoinDeteils，CryptoCurrency.class）;
System.out.println（比特币）;
$ b
我得到一个错误
你在代码中看到什么错误吗？谢谢。
解决方案错误消息表明JSON字符串包含一个数组（was BEGIN_ARRAY ），但是你试着将它解析为一个对象（Expected BEGIN_OBJECT）。
正如我们在你提供的JSON字符串中看到的，它确实是一个数组，你感兴趣的对象被包裹在方括号（ [...] ）中。
尝试将其解析为例如 List< CryptoCurrency> 然后：
Type listType = new TypeToken< ArrayList< CryptoCurrency>>（）{}。getType（）;
列表< CryptoCurrency> list = new Gson（）。fromJson（jsonString，listType）;
（类型 java.lang.reflect.Type 。）
So I am trying to parse a JSON object in Java using Gson.I am trying to consume an API from a website.This is the ticker:https://api.coinmarketcap.com/v1/ticker/bitcoin/
The JSON looks like this:
[
{
"id": "bitcoin",
"name": "Bitcoin",
"symbol": "BTC",
"rank": "1",
"price_usd": "3591.95",
"price_btc": "1.0",
"24h_volume_usd": "3263990000.0",
"market_cap_usd": "59516499433.0",
"available_supply": "16569412.0",
"total_supply": "16569412.0",
"percent_change_1h": "1.02",
"percent_change_24h": "15.59",
"percent_change_7d": "-15.18",
"last_updated": "1505563475"
}
]
I am using Jersey for consuming the API and I want to transform this JSON into an object.
This is the object that should be built by parsing the JSON:
public class CryptoCurrency {
String id;
String name;
String symbol;
String rank;
String price_usd;
String price_btc;
String market_cap_usd;
String available_supply;
String total_supply;
String percent_change_1h;
String percent_change_24h;
String percent_change_7d;
String last_updated;
}
This is my code:
public class CoinMarketCap {
public static void main(String[] args) {
Client client = ClientBuilder.newClient();
WebTarget target = client.target("https://api.coinmarketcap.com/v1/ticker/bitcoin/");
String bitoinDeteils = target.request(MediaType.TEXT_XML).get(String.class);
Gson gson = new GsonBuilder().create();
CryptoCurrency bitcoin = gson.fromJson(bitoinDeteils, CryptoCurrency.class);
System.out.println(bitcoin);
}
}
I Get an error
Do you see anything wrong in my code? thanks.
解决方案 The error message says that the JSON string contains an array ("was BEGIN_ARRAY"), but you try it parse it as an object ("Expected BEGIN_OBJECT").
As we can see in the JSON string you provided, it's indeed an array, the object you're interested in is wrapped in square brackets ([ ... ]).
Try to parse it for example as a List<CryptoCurrency> then:
Type listType = new TypeToken<ArrayList<CryptoCurrency>>(){}.getType();
List<CryptoCurrency> list = new Gson().fromJson(jsonString, listType);
(Type is java.lang.reflect.Type.)
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