我的对象包含一个String,long和int。对象称为跟踪器,我有一个跟踪器的arrayList。当我尝试使用toJson时出现错误。 fromJson也是如此。我每次都得到这个。
FATAL EXCEPTION: main
Process: com.example.unknownuser.scrapstable, PID: 13550
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.unknownuser.scrapstable/com.example.unknownuser.scrapstable.MainActivity}: java.lang.IllegalArgumentException: class android.content.res.ColorStateList declares multiple JSON fields named mChangingConfigurations
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
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:170)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:100)
at com.google.gson.Gson.getAdapter(Gson.java:423)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:115)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:164)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:100)
at com.google.gson.Gson.getAdapter(Gson.java:423)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:115)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:164)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:100)
at com.google.gson.Gson.getAdapter(Gson.java:423)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:115)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:164)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:100)
at com.google.gson.Gson.getAdapter(Gson.java:423)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:115)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:164)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:100)
at com.google.gson.Gson.getAdapter(Gson.java:423)
at com.google.gson.internal.bind.CollectionTypeAdapterFactory.create(CollectionTypeAdapterFactory.java:53)
at com.google.gson.Gson.getAdapter(Gson.java:423)
at com.google.gson.Gson.fromJson(Gson.java:887)
at com.google.gson.Gson.fromJson(Gson.java:853)
at com.google.gson.Gson.fromJson(Gson.java:802)
at com.example.unknownuser.scrapstable.MainActivity.onCreate(MainActivity.java:109)
at android.app.Activity.performCreate(Activity.java:6662)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
我有一个活动A,尝试保存跟踪器的ArrayList:
Tracker trax = new Tracker(description, timeToCount, imageID);
track.add(trax);
sharedPref = getSharedPreferences("pref", Context.MODE_PRIVATE);
editor = sharedPref.edit();
Gson gson = new Gson();
String json = gson.toJson(track);
editor.putString("LeftoverList", json);
editor.commit();
在活动B中,我尝试检索Trackers的ArrayList
ArrayList<Tracker> foodList;
sharedPref = getSharedPreferences("pref", Context.MODE_PRIVATE);
gson = new Gson();
json = sharedPref.getString("LeftoverList", " ");
type = new TypeToken<ArrayList<Tracker>>(){}.getType();
foodList = gson.fromJson(json, type);
使用方法
toJson
和fromJson
的行给了我致命的异常。非常感谢任何帮助的人。 最佳答案
似乎您正在尝试将列表转换为对象而不是列表的json。您可以只创建一个包装器类来保存列表并对其进行序列化/反序列化。
创建一个简单的类,作为您的List的包装器。
class TrackWrapper {
List<Tracker> trackList;
public TrackWrapper(List<Tracker> tracks){
this.trackList = tracks;
}
}
将项目添加到列表
Tracker trax = new Tracker(description, timeToCount, imageID);
track.add(trax);
创建包装器类的实例并在其中传递列表
TrackWrapper wrapper = new TrackWrapper(trax);
序列化包装器
Gson gson = new Gson();
String json = gson.toJson(wrapper);