Parcelable and inheritance in Android

Here is my best solution, I would be happy to hear from somebody that had a thought about it.

public abstract class A implements Parcelable {    private int a;    protected A(int a) {        this.a = a;    }    public void writeToParcel(Parcel out, int flags) {        out.writeInt(a);    }    protected A(Parcel in) {        a = in.readInt();    }}public class B extends A {    private int b;    public B(int a, int b) {        super(a);        this.b = b;    }    public static final Parcelable.Creator<B> CREATOR = new Parcelable.Creator<B>() {        public B createFromParcel(Parcel in) {            return new B(in);        }        public B[] newArray(int size) {            return new B[size];        }    };    public int describeContents() {        return 0;    }    public void writeToParcel(Parcel out, int flags) {        super.writeToParcel(out, flags);        out.writeInt(b);    }    private B(Parcel in) {        super(in);        b = in.readInt();    }}

This is my variant. I think it's nice because it shows the symmetry between the virtual read- and write- methods very clearly.

Side note: I think Google did a really poor job at designing the Parcelable interface.

public abstract class A implements Parcelable {    private int a;    protected A(int a) {        this.a = a;    }    public void writeToParcel(Parcel out, int flags) {        out.writeInt(a);    }    public void readFromParcel(Parcel in) {        a = in.readInt();    }}public class B extends A {    private int b;    public B(int a, int b) {        super(a);        this.b = b;    }    public static final Parcelable.Creator<B> CREATOR = new Parcelable.Creator<B>() {        public B createFromParcel(Parcel in) {            return new B(in);        }        public B[] newArray(int size) {            return new B[size];        }    };    public int describeContents() {        return 0;    }    public void writeToParcel(Parcel out, int flags) {        super.writeToParcel(out, flags);        out.writeInt(b);    }    public void readFromParcel(Parcel in) {        super(in);        b = in.readInt();    }}

Here is the implementation for class A in a real world setting since class B will likely have more than one object with different types other than int

It uses reflection to get the types. Then uses a sorting function to sort the fields so that reading and writing happen in the same order.

https://github.com/awadalaa/Android-Global-Parcelable