Using Parcelable To Pass Highly Nested Classes Between Activities

Suppose I want to store a custom object of type MyObject in an Intent. The way to do this is to make MyObject implement Parcelable. If one of the fields of MyObject is also a custo

Solution 1:

I would (and did) go with Parceler: https://github.com/johncarl81/parceler

Parceler is a code generation library that generates the Android Parcelable boilerplate source code. No longer do you have to implement the Parcelable interface, the writeToParcel() or createFromParcel() or the public static final CREATOR. You simply annotate a POJO with @Parcel and Parceler does the rest.

It's really easy to use.

Solution 2:

It is recommended to use Parcelable when dealing with passing custom Objects through intents in Android. There isn't an "easy" work around. Since you are dealing with just one extra level of a custom Object (Widget), I would recommend you make WidgetParcelable also. You can also check out this link to see why it is the better approach than using default Serialization. https://coderwall.com/p/vfbing/passing-objects-between-activities-in-android

Solution 3:

If your classes are beans, the best solution is the accepted one. If not, I have found that you can (slightly) reduce the pain of implementing Parcelable by creating abstract classes ParcelablePlus and CreatorPlus like this.

ParcelablePlus:

abstractclassParcelablePlusimplementsParcelable {

    @OverridepublicfinalintdescribeContents() {
        return0;
    }
}

CreatorPlus:

abstractclassCreatorPlus<T extendsParcelable> implementsParcelable.Creator<T> {

    privatefinal Class<T> clazz;

    CreatorPlus(Class<T> clazz) {
        this.clazz = clazz;
    }

    @Override@SuppressWarnings("unchecked")publicfinal T[] newArray(int size) {
        // Safe as long as T is not a generic type.return (T[]) Array.newInstance(clazz, size);
    }
}

Then the Widget class becomes:

publicfinalclassWidgetextendsParcelablePlus {

    privatefinalint a;
    privatefinal String b;

    Widget(int a, String b) {
        this.a = a;
        this.b = b;
    }

    @OverridepublicvoidwriteToParcel(Parcel out, int flags) {
        out.writeInt(a);
        out.writeString(b);
    }

    publicstaticfinal Creator<Widget> CREATOR = newCreatorPlus<Widget>(Widget.class) {
        @Overridepublic Widget createFromParcel(Parcel in) {
            returnnewWidget(in.readInt(), in.readString());
        }
    };
}