Question

这是我想要转换为POJO的JSON信息 http://45.x.x.65/api/getCoins

不知何故，当我尝试发送帖子请求并尝试将json信息转换为模型时，我得到了这个恼人的错误：

com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected a string but was BEGIN_OBJECT at line 1 column 156 path $.coins[0].currencies[0]

这是我接收json文件的请求代码：

String url = "http://45.x.x.65/api/getCoins";
    RequestQueue queue = Volley.newRequestQueue(this);
    StringRequest postRequest = new StringRequest(Request.Method.POST, url,
            new Response.Listener<String>()
            {
                @Override
                public void onResponse(String response) {
                    // response
                    Log.d("Response", response);
                    Gson gson = new Gson();
                    CoinStats coinStats = gson.fromJson(response, CoinStats.class);

//                        Toast.makeText(getApplicationContext(),coinStats.getExchange(),Toast.LENGTH_SHORT).show();
                }
            },
            new Response.ErrorListener()
            {
                @Override
                public void onErrorResponse(VolleyError error) {
                    // error
                    Log.d("Error.Response", error.getMessage());
                }
            }
    ) {
        @Override
        protected Map<String, String> getParams()
        {
            Map<String, String>  params = new HashMap<String, String>();

            return params;
        }

        @Override
        public Map<String, String> getHeaders() throws AuthFailureError {
            Map<String,String> params = new HashMap<String, String>();
            params.put("Content-Type","application/json");
            return params;
        }
    };
    queue.add(postRequest);

这些是模型文件：

CoinStats

import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;

import java.util.List;


public class CoinStats {

@SerializedName("result")
@Expose
private Boolean result;
@SerializedName("exchange")
@Expose
private String exchange;
@SerializedName("from")
@Expose
private List<String> from = null;
@SerializedName("to")
@Expose
private List<String> to = null;
@SerializedName("coins")
@Expose
private List<Coin> coins = null;

public Boolean getResult() {
    return result;
}

public void setResult(Boolean result) {
    this.result = result;
}

public String getExchange() {
    return exchange;
}

public void setExchange(String exchange) {
    this.exchange = exchange;
}

public List<String> getFrom() {
    return from;
}

public void setFrom(List<String> from) {
    this.from = from;
}

public List<String> getTo() {
    return to;
}

public void setTo(List<String> to) {
    this.to = to;
}

public List<Coin> getCoins() {
    return coins;
}

public void setCoins(List<Coin> coins) {
    this.coins = coins;
}

}

硬币

import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;

import java.util.Currency;
import java.util.List;

public class Coin {

@SerializedName("symbol")
@Expose
private String symbol;
@SerializedName("name")
@Expose
private String name;
@SerializedName("icon")
@Expose
private String icon;
@SerializedName("currencies")
@Expose
private List<Currency> currencies = null;

public String getSymbol() {
    return symbol;
}

public void setSymbol(String symbol) {
    this.symbol = symbol;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public String getIcon() {
    return icon;
}

public void setIcon(String icon) {
    this.icon = icon;
}

public List<Currency> getCurrencies() {
    return currencies;
}

public void setCurrencies(List<Currency> currencies) {
    this.currencies = currencies;
}
}

货币

import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;

public class Currency {

@SerializedName("type")
@Expose
private String type;
@SerializedName("price")
@Expose
private Double price;
@SerializedName("when")
@Expose
private Integer when;
@SerializedName("volume")
@Expose
private Integer volume;
@SerializedName("supply")
@Expose
private Double supply;
@SerializedName("market_cap")
@Expose
private Double marketCap;
@SerializedName("volume_24h")
@Expose
private Double volume24h;
@SerializedName("open_24h")
@Expose
private Double open24h;
@SerializedName("high_24h")
@Expose
private Double high24h;
@SerializedName("low_24h")
@Expose
private Double low24h;
@SerializedName("change_24h")
@Expose
private Double change24h;
@SerializedName("percentage_24h")
@Expose
private Double percentage24h;

public String getType() {
    return type;
}

public void setType(String type) {
    this.type = type;
}

public Double getPrice() {
    return price;
}

public void setPrice(Double price) {
    this.price = price;
}

public Integer getWhen() {
    return when;
}

public void setWhen(Integer when) {
    this.when = when;
}

public Integer getVolume() {
    return volume;
}

public void setVolume(Integer volume) {
    this.volume = volume;
}

public Double getSupply() {
    return supply;
}

public void setSupply(Double supply) { this.supply = supply; }

public Double getMarketCap() {
    return marketCap;
}

public void setMarketCap(Double marketCap) {
    this.marketCap = marketCap;
}

public Double getVolume24h() {
    return volume24h;
}

public void setVolume24h(Double volume24h) {
    this.volume24h = volume24h;
}

public Double getOpen24h() {
    return open24h;
}

public void setOpen24h(Double open24h) {
    this.open24h = open24h;
}

public Double getHigh24h() {
    return high24h;
}

public void setHigh24h(Double high24h) {
    this.high24h = high24h;
}

public Double getLow24h() {
    return low24h;
}

public void setLow24h(Double low24h) {
    this.low24h = low24h;
}

public Double getChange24h() {
    return change24h;
}

public void setChange24h(Double change24h) {
    this.change24h = change24h;
}

public Double getPercentage24h() {
    return percentage24h;
}

public void setPercentage24h(Double percentage24h) {
    this.percentage24h = percentage24h;
}

}

Answer 1

您正在导入java.util.Currency而不是您自己的自定义POJO，这可能就是GSON无法正确构建对象的原因。

Answer 2

我猜你的json是如何形成的，存在某种问题。应该与硬币对应的jsonString部分未正确转换为List。您是否有机会添加要转换为帖子的jsonstring？

当我使用List时，为什么json convertion期望String而不是Object

2 个答案: