gson.toJson声明了多个名为XX的JSON字段

Question

我有一个类型为A的单个自定义对象和一个包含类型B的自定义对象的ArrayList，我希望使用gson将其存储在共享首选项中。 对象A正常工作，但是当我尝试存储对象B的列表甚至仅存储对象B的一个实例时，会出现以下错误消息：

2019-01-07 13:05:21.610 28295-28295/com.example.aev.quizzle E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.aev.quizzle, PID: 28295
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.aev.quizzle/com.example.aev.quizzle.activities.MapsActivity}: java.lang.IllegalArgumentException: class android.content.res.ColorStateList declares multiple JSON fields named mChangingConfigurations
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3194)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3302)
    at android.app.ActivityThread.-wrap12(Unknown Source:0)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1891)
    at android.os.Handler.dispatchMessage(Handler.java:108)
    at android.os.Looper.loop(Looper.java:166)
    at android.app.ActivityThread.main(ActivityThread.java:7425)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:245)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:921)
 Caused by: java.lang.IllegalArgumentException: class android.content.res.ColorStateList declares multiple JSON fields named mChangingConfigurations
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:172)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:102)
    at com.google.gson.Gson.getAdapter(Gson.java:458)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:117)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:166)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:102)
    at com.google.gson.Gson.getAdapter(Gson.java:458)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:117)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:166)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:102)
    at com.google.gson.Gson.getAdapter(Gson.java:458)
    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:56)
    at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.write(CollectionTypeAdapterFactory.java:97)
    at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.write(CollectionTypeAdapterFactory.java:61)
    at com.google.gson.Gson.toJson(Gson.java:704)
    at com.google.gson.Gson.toJson(Gson.java:683)
    at com.google.gson.Gson.toJson(Gson.java:638)
    at com.google.gson.Gson.toJson(Gson.java:618)
    at com.example.aev.quizzle.activities.MapsActivity.generateThemes(MapsActivity.java:592)
    at com.example.aev.quizzle.activities.MapsActivity.onCreate(MapsActivity.java:164)
    at android.app.Activity.performCreate(Activity.java:7383)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1218)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3147)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3302) 
    at android.app.ActivityThread.-wrap12(Unknown Source:0) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1891) 
    at android.os.Handler.dispatchMessage(Handler.java:108) 
    at android.os.Looper.loop(Looper.java:166) 
    at android.app.ActivityThread.main(ActivityThread.java:7425) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:245) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:921) 

我这样存储数组列表：

themes = new ArrayList<>();
themes.add(new Theme(0, this));
themes.add(new Theme(1, this));
themes.add(new Theme(2, this));

String jsonTheme = gson.toJson(themes);
prefsEditor.putString("themes", jsonTheme);
prefsEditor.commit();

我的班级主题看起来像这样：

public class Theme implements Parcelable {
    public ImageView icon;
    public int themeID;
    //public Question[] questions = new Question[14];
    public List<Question> questions = new ArrayList<>();
    boolean unlocked;
    Context context;

我在超级类和应该存储的对象中看到了类似的问题，变量名称相同，但是就我而言，我没有在Theme类中扩展另一个类。 错误指向行说

String jsonTheme = gson.toJson(themes);

我是错误地对待gson对象还是错过了任何东西？

Answer 1

使用@Transient是解决此序列化问题的一种方法。 正如您在反序列化之后可能还注意到的那样，您需要为每个反序列化的Theme设置这些ImageView和Context ，这可能是一个小问题。

您也可以考虑将要保留的数据与诸如视图和上下文之类的瞬态数据分开。 仅查看了代码的一小部分，您的结构可能类似于：

就像是：

public class Theme {
    public ImageView icon;
    Context context;
    ThemeData themeData

    public Theme(Context contect, ImageView icon, ThemeData themeData) {
        this.context = context;
        this.icon = icon;
        themeData = themeData;
    }

    public void doSomethingWithThemeDataAndViewAndContext() {
        // whatever you need to do in Theme
    }
}

然后， ThemeData包含所有非瞬态字段，然后将这些字段持久SharedPreferences ：

public class ThemeData {
    public int themeID;
    //public Question[] questions = new Question[14];
    public List<Question> questions = new ArrayList<>();
    boolean unlocked;
}

另请注意：我认为，如果您使用GSON序列化主题并将其另存为SharedPreferences的JSON字符串，则无需实现Parcelable因此我将其删除。