用不同的对象解析json数组到他们的类 [英] Parse json array with different objects to their classes

问题描述

我有以下json:

[
    {
        "type": 1,
        "Steps": {
            "steps": steps
        }
    },
    {
        "type": 2,
        "HeartRate": {
            "heartrates": heartRates
        }
    }
]

字段步骤只是一个int，heartRates是一个int的数组.我想要 使用gson将其解析为两个类. 我在stackoverflow上发现了类似的问题:如何解析多个json数组是gson的对象吗?并尝试了一下，但是没有用.这是我的代码:

The field steps is just an int an heartRates is an array of int's. I want to parse this using gson to two classes. I found a similar question on stackoverflow: How parse json array with multiple objects by gson? and tried it but it didn't work. This is my code:

public class DataModels extends ArrayList<DataModels.Container> {

public class Container {
    public int type;
    public Object object;
}

public class Steps {

    double steps;

    public Steps(double steps) {
        this.steps = steps;
    }

    public double getSteps() {
        return steps;
    }

    @Override
    public String toString() {
        return "Steps: " + steps;
    }

}

public class HeartRate {

    int heartRate;

    public HeartRate(int hr) {
        heartRate = hr;
    }

    public double getHeartRate() {
        return heartRate;
    }

    @Override
    public String toString() {
        return "Heart rate: " + heartRate;
    }

}
}

然后解析我的json:

Then for parsing my json:

public String getJSONMessage(String gearSData) {
    System.out.println(gearSData);
    Gson gson = new Gson();
    DataModels model = gson.fromJson(gearSData, DataModels.class);
    System.out.println(model);
    for (DataModels.Container container: model) {

        System.out.println(container.type);
        System.out.println(container.object);
        String innerJson = gson.toJson(container.object);
        System.out.println("InnerJson: " + innerJson);

        switch (container.type) {
            case 1:
                DataModels.Steps steps = gson.fromJson(innerJson, DataModels.Steps.class);
                System.out.println(steps);
                break;
            case 2:
                DataModels.HeartRate heartRate = gson.fromJson(innerJson, DataModels.HeartRate.class);
                System.out.println(heartRate);
                break;
        }
    }
}

该类型可以正确解析，但innerjson为null，我不知道为什么.有人可以解释一下吗，还是有人知道更好的方法?

The type gets parsed correctly but the innerjson is null and I don't know why. Can somebody explain this or does someone know a better way to do this?

推荐答案

您的字段名称应与json中的字段相同.我刚刚重命名了您的类的字段，并且您的代码对我来说很好用:

Names of your fields should be equal to the fields in json. I just renamed fields of your classes and your code works well for me:

public static String getJSONMessage(String gearSData) {
    System.out.println(gearSData);
    Gson gson = new Gson();
    DataModels model = gson.fromJson(gearSData, DataModels.class);
    System.out.println(model);
    for (DataModels.Container container : model) {

        System.out.println(container.type);
        String innerJson = gson.toJson(container.type == 1 ? container.Steps : container.HeartRate);
        System.out.println("InnerJson: " + innerJson);
        //...
    }
    return null;
}

public static class DataModels extends ArrayList<DataModels.Container> {
    public static class Container {
        public int type;
        public StepsType Steps; // object for type 1
        public HeartRateType HeartRate; // object for type 2
    }

    public static class StepsType {
        double steps;
        //...
    }

    public static class HeartRateType {
        int heartrates;
        //...
    }
}

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