I want to pass an object to a bundle. Now I did the conversion to a Json object with GSON.
The bundle is passed, the bundle has the right string representation but when I create the object from the string I get a huge error.
FATAL EXCEPTION: main
java.lang.RuntimeException: Failed to invoke private android.net.Uri() with no args
at com.google.gson.internal.ConstructorConstructor$3.construct(ConstructorConstructor.java:107)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:162)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:93)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:172)
at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:40)
at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:81)
at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:60)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:93)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:172)
at com.google.gson.Gson.fromJson(Gson.java:803)
at com.google.gson.Gson.fromJson(Gson.java:768)
at com.google.gson.Gson.fromJson(Gson.java:717)
at com.google.gson.Gson.fromJson(Gson.java:689)
at com.test.fragment.QFragment.onCreateView(QFragment.java:54)
at android.app.Fragment.performCreateView(Fragment.java:1788)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:899)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1101)
at android.app.BackStackRecord.run(BackStackRecord.java:688)
at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1559)
at android.app.FragmentManagerImpl$1.run(FragmentManager.java:445)
at android.os.Handler.handleCallback(Handler.java:730)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:158)
at android.app.ActivityThread.main(ActivityThread.java:5789)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1027)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:843)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.InstantiationException: can't instantiate class android.net.Uri
at java.lang.reflect.Constructor.constructNative(Native Method)
at java.lang.reflect.Constructor.newInstance(Constructor.java:417)
at com.google.gson.internal.ConstructorConstructor$3.construct(ConstructorConstructor.java:104)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:162)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:93)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:172)
at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:40)
at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:81)
at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:60)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:93)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:172)
at com.google.gson.Gson.fromJson(Gson.java:803)
at com.google.gson.Gson.fromJson(Gson.java:768)
at com.google.gson.Gson.fromJson(Gson.java:717)
at com.google.gson.Gson.fromJson(Gson.java:689)
at com.test.fragment.QFragment.onCreateView(QFragment.java:54)
at android.app.Fragment.performCreateView(Fragment.java:1788)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:899)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1101)
at android.app.BackStackRecord.run(BackStackRecord.java:688)
at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1559)
at android.app.FragmentManagerImpl$1.run(FragmentManager.java:445)
at android.os.Handler.handleCallback(Handler.java:730)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:158)
at android.app.ActivityThread.main(ActivityThread.java:5789)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1027)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:843)
at dalvik.system.NativeStart.main(Native Method)
I'm doing the conversion like this:
public static QFragment newInstance(FModel oModel) {
QFragment fragment = new QFragment();
fragment.mOModel = oModel;
Bundle bdl = new Bundle();
bdl.putString("oModel", new Gson().toJson(oModel));
fragment.setArguments(bdl);
return fragment;
}
and in my fragment on the createView:
String jsonMyObject = null;
Bundle args = this.getArguments();
if (args != null) {
jsonMyObject = args.getString("oModel");
}
mOrderModel = new Gson().fromJson(jsonMyObject, FModel.class);
Whats the best way to fix this? Do I need to change to serializable or parcelable?
ConclusionBoth Gson and Jackson are good options for serializing/deserializing JSON data, simple to use and well documented. Advantages of Gson: Simplicity of toJson/fromJson in the simple cases. For deserialization, do not need access to the Java entities.
Gson is not deprecated.
Gson is typically used by first constructing a Gson instance and then invoking toJson(Object) or fromJson(String, Class) methods on it. Gson instances are Thread-safe so you can reuse them freely across multiple threads.
Found the problem in the FModel there was indeed a Uri.
Solved this by writing:
public class UriSerializer implements JsonSerializer<Uri> {
public JsonElement serialize(Uri src, Type typeOfSrc, JsonSerializationContext context) {
return new JsonPrimitive(src.toString());
}
}
public class UriDeserializer implements JsonDeserializer<Uri> {
@Override
public Uri deserialize(final JsonElement src, final Type srcType,
final JsonDeserializationContext context) throws JsonParseException {
return Uri.parse(src.getAsString());
}
}
and doing the Gson conversion like this:
Gson gson = new GsonBuilder()
.registerTypeAdapter(Uri.class, new UriSerializer())
.create();
bdl.putString("oModel",gson.toJson(oModel));
and in the oncreate to rebuild this:
Gson gson = new GsonBuilder()
.registerTypeAdapter(Uri.class, new UriDeserializer())
.create();
jsonMyObject = args.getString("oModel");
mOrderModel = gson.fromJson(jsonMyObject, FModel.class);
FYI, you can use serialize and deserialize at the same time by combining your two interfaces implementations into a single class.
public class UriInOut implements JsonSerializer<Uri>, JsonDeserializer<Uri> {
@Override
public JsonElement serialize(Uri src, Type typeOfSrc, JsonSerializationContext context) {
return new JsonPrimitive(src.toString());
}
@Override
public Uri deserialize(final JsonElement src, final Type srcType,
final JsonDeserializationContext context) throws JsonParseException {
return Uri.parse(src.getAsString());
}
}
....
new GsonBuilder()
.registerTypeAdapter(Uri.class, new UriInOut())
.create();
You can also use TypeAdapter which is more efficient
public final class UriAdapter extends TypeAdapter<Uri> {
@Override
public void write(JsonWriter out, Uri uri) throws IOException {
out.value(uri.toString());
}
@Override
public Uri read(JsonReader in) throws IOException {
return Uri.parse(in.nextString());
}
}
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